Merge branch 'hathach:master' into master

40 files changed, 2098 insertions, 947 deletions

diff --git a/src/class/audio/audio.h b/src/class/audio/audio.h
index 6f9c1a6b5..70d431282 100644
--- a/src/class/audio/audio.h
+++ b/src/class/audio/audio.h
@@ -1,4 +1,4 @@
-/* 
+/*
  * The MIT License (MIT)
  *
  * Copyright (c) 2019 Ha Thach (tinyusb.org)
@@ -721,11 +721,13 @@ typedef struct TU_ATTR_PACKED
   uint8_t bLength            ; ///< Size of this descriptor, in bytes: 17.
   uint8_t bDescriptorType    ; ///< Descriptor Type. Value: TUSB_DESC_CS_INTERFACE.
   uint8_t bDescriptorSubType ; ///< Descriptor SubType. Value: AUDIO_CS_AC_INTERFACE_INPUT_TERMINAL.
+  uint8_t bTerminalID        ; ///< Constant uniquely identifying the Terminal within the audio function. This value is used in all requests to address this terminal.
   uint16_t wTerminalType     ; ///< Constant characterizing the type of Terminal. See: audio_terminal_type_t for USB streaming and audio_terminal_input_type_t for other input types.
   uint8_t bAssocTerminal     ; ///< ID of the Output Terminal to which this Input Terminal is associated.
   uint8_t bCSourceID         ; ///< ID of the Clock Entity to which this Input Terminal is connected.
   uint8_t bNrChannels        ; ///< Number of logical output channels in the Terminal’s output audio channel cluster.
   uint32_t bmChannelConfig   ; ///< Describes the spatial location of the logical channels. See:audio_channel_config_t.
+  uint8_t iChannelNames      ; ///< Index of a string descriptor, describing the name of the first logical channel.
   uint16_t bmControls        ; ///< See: audio_terminal_input_control_pos_t.
   uint8_t iTerminal          ; ///< Index of a string descriptor, describing the Input Terminal.
 } audio_desc_input_terminal_t;
@@ -822,10 +824,10 @@ typedef struct TU_ATTR_PACKED
             uint8_t type      :  2; ///< Request type tusb_request_type_t.
             uint8_t direction :  1; ///< Direction type. tusb_dir_t
         } bmRequestType_bit;
-        
+
         uint8_t bmRequestType;
     };
-    
+
     uint8_t bRequest;  ///< Request type audio_cs_req_t
     uint8_t bChannelNumber;
     uint8_t bControlSelector;
diff --git a/src/class/audio/audio_device.c b/src/class/audio/audio_device.c
index 06979b09e..f487fe60e 100644
--- a/src/class/audio/audio_device.c
+++ b/src/class/audio/audio_device.c
@@ -1,4 +1,4 @@
-/* 
+/*
  * The MIT License (MIT)
  *
  * Copyright (c) 2020 Reinhard Panhuber, Jerzy Kasenberg
@@ -66,51 +66,41 @@
 
 // Use ring buffer if it's available, some MCUs need extra RAM requirements
 #ifndef TUD_AUDIO_PREFER_RING_BUFFER
-#if CFG_TUSB_MCU == OPT_MCU_LPC43XX || CFG_TUSB_MCU == OPT_MCU_LPC18XX || CFG_TUSB_MCU == OPT_MCU_MIMXRT10XX
-#define TUD_AUDIO_PREFER_RING_BUFFER 0
-#else
-#define TUD_AUDIO_PREFER_RING_BUFFER 1
-#endif
+  #if CFG_TUSB_MCU == OPT_MCU_LPC43XX || CFG_TUSB_MCU == OPT_MCU_LPC18XX || CFG_TUSB_MCU == OPT_MCU_MIMXRT
+    #define TUD_AUDIO_PREFER_RING_BUFFER 0
+  #else
+    #define TUD_AUDIO_PREFER_RING_BUFFER 1
+  #endif
 #endif
 
 // Linear buffer in case target MCU is not capable of handling a ring buffer FIFO e.g. no hardware buffer
 // is available or driver is would need to be changed dramatically
 
-// Only STM32 synopsys and dcd_transdimension use non-linear buffer for now
-// Synopsys detection copied from dcd_synopsys.c (refactor later on)
-#if defined (STM32F105x8) || defined (STM32F105xB) || defined (STM32F105xC) || \
-    defined (STM32F107xB) || defined (STM32F107xC)
-#define STM32F1_SYNOPSYS
-#endif
-
-#if defined (STM32L475xx) || defined (STM32L476xx) ||                          \
-    defined (STM32L485xx) || defined (STM32L486xx) || defined (STM32L496xx) || \
-    defined (STM32L4R5xx) || defined (STM32L4R7xx) || defined (STM32L4R9xx) || \
-    defined (STM32L4S5xx) || defined (STM32L4S7xx) || defined (STM32L4S9xx)
-#define STM32L4_SYNOPSYS
-#endif
-
-#if (CFG_TUSB_MCU == OPT_MCU_STM32F1 && defined(STM32F1_SYNOPSYS)) || \
-    CFG_TUSB_MCU == OPT_MCU_STM32F2                               || \
-    CFG_TUSB_MCU == OPT_MCU_STM32F4                               || \
-    CFG_TUSB_MCU == OPT_MCU_STM32F7                               || \
-    CFG_TUSB_MCU == OPT_MCU_STM32H7                               || \
-    (CFG_TUSB_MCU == OPT_MCU_STM32L4 && defined(STM32L4_SYNOPSYS)) || \
-    CFG_TUSB_MCU == OPT_MCU_RX63X                                 || \
-    CFG_TUSB_MCU == OPT_MCU_RX65X                                 || \
-    CFG_TUSB_MCU == OPT_MCU_RX72N                                 || \
-    CFG_TUSB_MCU == OPT_MCU_GD32VF103                             || \
-    CFG_TUSB_MCU == OPT_MCU_LPC18XX                               || \
-    CFG_TUSB_MCU == OPT_MCU_LPC43XX                               || \
-    CFG_TUSB_MCU == OPT_MCU_MIMXRT10XX                            || \
+// Only STM32 and dcd_transdimension use non-linear buffer for now
+// dwc2 except esp32sx (since it may use dcd_esp32sx)
+#if (defined(TUP_USBIP_DWC2) && !TU_CHECK_MCU(OPT_MCU_ESP32S2, OPT_MCU_ESP32S3)) || \
+    defined(TUP_USBIP_FSDEV)          || \
+    CFG_TUSB_MCU == OPT_MCU_RX63X     || \
+    CFG_TUSB_MCU == OPT_MCU_RX65X     || \
+    CFG_TUSB_MCU == OPT_MCU_RX72N     || \
+    CFG_TUSB_MCU == OPT_MCU_LPC18XX   || \
+    CFG_TUSB_MCU == OPT_MCU_LPC43XX   || \
+    CFG_TUSB_MCU == OPT_MCU_MIMXRT    || \
     CFG_TUSB_MCU == OPT_MCU_MSP432E4
-#if TUD_AUDIO_PREFER_RING_BUFFER
-#define  USE_LINEAR_BUFFER     0
+  #if TUD_AUDIO_PREFER_RING_BUFFER
+    #define  USE_LINEAR_BUFFER     0
+  #else
+    #define  USE_LINEAR_BUFFER     1
+  #endif
 #else
-#define  USE_LINEAR_BUFFER     1
+  #define  USE_LINEAR_BUFFER     1
 #endif
+
+// Temporarily put the check here for stm32_fsdev
+#ifdef TUP_USBIP_FSDEV
+  #define  USE_ISO_EP_ALLOCATION   1
 #else
-#define  USE_LINEAR_BUFFER     1
+  #define  USE_ISO_EP_ALLOCATION   0
 #endif
 
 // Declaration of buffers
@@ -122,143 +112,159 @@
 
 // EP IN software buffers and mutexes
 #if CFG_TUD_AUDIO_ENABLE_EP_IN && !CFG_TUD_AUDIO_ENABLE_ENCODING
-#if CFG_TUD_AUDIO_FUNC_1_EP_IN_SW_BUF_SZ > 0
-CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN uint8_t audio_ep_in_sw_buf_1[CFG_TUD_AUDIO_FUNC_1_EP_IN_SW_BUF_SZ];
-#if CFG_FIFO_MUTEX
-osal_mutex_def_t ep_in_ff_mutex_wr_1;                                                             // No need for read mutex as only USB driver reads from FIFO
-#endif
-#endif // CFG_TUD_AUDIO_FUNC_1_EP_IN_SW_BUF_SZ > 0
-#if CFG_TUD_AUDIO > 1 && CFG_TUD_AUDIO_FUNC_2_EP_IN_SW_BUF_SZ > 0
-CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN uint8_t audio_ep_in_sw_buf_2[CFG_TUD_AUDIO_FUNC_2_EP_IN_SW_BUF_SZ];
-#if CFG_FIFO_MUTEX
-osal_mutex_def_t ep_in_ff_mutex_wr_2;                                                             // No need for read mutex as only USB driver reads from FIFO
-#endif
-#endif // CFG_TUD_AUDIO > 1 && CFG_TUD_AUDIO_FUNC_2_EP_IN_SW_BUF_SZ > 0
-#if CFG_TUD_AUDIO > 2 && CFG_TUD_AUDIO_FUNC_3_EP_IN_SW_BUF_SZ > 0
-CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN uint8_t audio_ep_in_sw_buf_3[CFG_TUD_AUDIO_FUNC_3_EP_IN_SW_BUF_SZ];
-#if CFG_FIFO_MUTEX
-osal_mutex_def_t ep_in_ff_mutex_wr_3;                                                             // No need for read mutex as only USB driver reads from FIFO
-#endif
-#endif // CFG_TUD_AUDIO > 2 && CFG_TUD_AUDIO_FUNC_3_EP_IN_SW_BUF_SZ > 0
+  #if CFG_TUD_AUDIO_FUNC_1_EP_IN_SW_BUF_SZ > 0
+    CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN uint8_t audio_ep_in_sw_buf_1[CFG_TUD_AUDIO_FUNC_1_EP_IN_SW_BUF_SZ];
+    #if CFG_FIFO_MUTEX
+    osal_mutex_def_t ep_in_ff_mutex_wr_1; // No need for read mutex as only USB driver reads from FIFO
+    #endif
+  #endif // CFG_TUD_AUDIO_FUNC_1_EP_IN_SW_BUF_SZ > 0
+
+  #if CFG_TUD_AUDIO > 1 && CFG_TUD_AUDIO_FUNC_2_EP_IN_SW_BUF_SZ > 0
+    CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN uint8_t audio_ep_in_sw_buf_2[CFG_TUD_AUDIO_FUNC_2_EP_IN_SW_BUF_SZ];
+    #if CFG_FIFO_MUTEX
+    osal_mutex_def_t ep_in_ff_mutex_wr_2; // No need for read mutex as only USB driver reads from FIFO
+    #endif
+  #endif // CFG_TUD_AUDIO > 1 && CFG_TUD_AUDIO_FUNC_2_EP_IN_SW_BUF_SZ > 0
+
+  #if CFG_TUD_AUDIO > 2 && CFG_TUD_AUDIO_FUNC_3_EP_IN_SW_BUF_SZ > 0
+    CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN uint8_t audio_ep_in_sw_buf_3[CFG_TUD_AUDIO_FUNC_3_EP_IN_SW_BUF_SZ];
+    #if CFG_FIFO_MUTEX
+    osal_mutex_def_t ep_in_ff_mutex_wr_3; // No need for read mutex as only USB driver reads from FIFO
+    #endif
+  #endif // CFG_TUD_AUDIO > 2 && CFG_TUD_AUDIO_FUNC_3_EP_IN_SW_BUF_SZ > 0
 #endif // CFG_TUD_AUDIO_ENABLE_EP_IN && !CFG_TUD_AUDIO_ENABLE_ENCODING
 
 // Linear buffer TX in case:
 // - target MCU is not capable of handling a ring buffer FIFO e.g. no hardware buffer is available or driver is would need to be changed dramatically OR
 // - the software encoding is used - in this case the linear buffers serve as a target memory where logical channels are encoded into
 #if CFG_TUD_AUDIO_ENABLE_EP_IN && (USE_LINEAR_BUFFER || CFG_TUD_AUDIO_ENABLE_ENCODING)
-#if CFG_TUD_AUDIO_FUNC_1_EP_IN_SZ_MAX > 0
-CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN uint8_t lin_buf_in_1[CFG_TUD_AUDIO_FUNC_1_EP_IN_SZ_MAX];
-#endif
-#if CFG_TUD_AUDIO > 1 && CFG_TUD_AUDIO_FUNC_2_EP_IN_SZ_MAX > 0
-CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN uint8_t lin_buf_in_2[CFG_TUD_AUDIO_FUNC_2_EP_IN_SZ_MAX];
-#endif
-#if CFG_TUD_AUDIO > 2 && CFG_TUD_AUDIO_FUNC_3_EP_IN_SZ_MAX > 0
-CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN uint8_t lin_buf_in_3[CFG_TUD_AUDIO_FUNC_3_EP_IN_SZ_MAX];
-#endif
+  #if CFG_TUD_AUDIO_FUNC_1_EP_IN_SZ_MAX > 0
+    CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN uint8_t lin_buf_in_1[CFG_TUD_AUDIO_FUNC_1_EP_IN_SZ_MAX];
+  #endif
+
+  #if CFG_TUD_AUDIO > 1 && CFG_TUD_AUDIO_FUNC_2_EP_IN_SZ_MAX > 0
+    CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN uint8_t lin_buf_in_2[CFG_TUD_AUDIO_FUNC_2_EP_IN_SZ_MAX];
+  #endif
+
+  #if CFG_TUD_AUDIO > 2 && CFG_TUD_AUDIO_FUNC_3_EP_IN_SZ_MAX > 0
+    CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN uint8_t lin_buf_in_3[CFG_TUD_AUDIO_FUNC_3_EP_IN_SZ_MAX];
+  #endif
 #endif // CFG_TUD_AUDIO_ENABLE_EP_IN && (USE_LINEAR_BUFFER || CFG_TUD_AUDIO_ENABLE_DECODING)
 
 // EP OUT software buffers and mutexes
 #if CFG_TUD_AUDIO_ENABLE_EP_OUT && !CFG_TUD_AUDIO_ENABLE_DECODING
-#if CFG_TUD_AUDIO_FUNC_1_EP_OUT_SW_BUF_SZ > 0
-CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN uint8_t audio_ep_out_sw_buf_1[CFG_TUD_AUDIO_FUNC_1_EP_OUT_SW_BUF_SZ];
-#if CFG_FIFO_MUTEX
-osal_mutex_def_t ep_out_ff_mutex_rd_1;                                                            // No need for write mutex as only USB driver writes into FIFO
-#endif
-#endif // CFG_TUD_AUDIO_FUNC_1_EP_OUT_SW_BUF_SZ > 0
-#if CFG_TUD_AUDIO > 1 && CFG_TUD_AUDIO_FUNC_2_EP_OUT_SW_BUF_SZ > 0
-CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN uint8_t audio_ep_out_sw_buf_2[CFG_TUD_AUDIO_FUNC_2_EP_OUT_SW_BUF_SZ];
-#if CFG_FIFO_MUTEX
-osal_mutex_def_t ep_out_ff_mutex_rd_2;                                                            // No need for write mutex as only USB driver writes into FIFO
-#endif
-#endif // CFG_TUD_AUDIO > 1 && CFG_TUD_AUDIO_FUNC_2_EP_OUT_SW_BUF_SZ > 0
-#if CFG_TUD_AUDIO > 2 && CFG_TUD_AUDIO_FUNC_3_EP_OUT_SW_BUF_SZ > 0
-CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN uint8_t audio_ep_out_sw_buf_3[CFG_TUD_AUDIO_FUNC_3_EP_OUT_SW_BUF_SZ];
-#if CFG_FIFO_MUTEX
-osal_mutex_def_t ep_out_ff_mutex_rd_3;                                                            // No need for write mutex as only USB driver writes into FIFO
-#endif
-#endif // CFG_TUD_AUDIO > 2 && CFG_TUD_AUDIO_FUNC_3_EP_OUT_SW_BUF_SZ > 0
+  #if CFG_TUD_AUDIO_FUNC_1_EP_OUT_SW_BUF_SZ > 0
+    CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN uint8_t audio_ep_out_sw_buf_1[CFG_TUD_AUDIO_FUNC_1_EP_OUT_SW_BUF_SZ];
+    #if CFG_FIFO_MUTEX
+    osal_mutex_def_t ep_out_ff_mutex_rd_1; // No need for write mutex as only USB driver writes into FIFO
+    #endif
+  #endif // CFG_TUD_AUDIO_FUNC_1_EP_OUT_SW_BUF_SZ > 0
+
+  #if CFG_TUD_AUDIO > 1 && CFG_TUD_AUDIO_FUNC_2_EP_OUT_SW_BUF_SZ > 0
+    CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN uint8_t audio_ep_out_sw_buf_2[CFG_TUD_AUDIO_FUNC_2_EP_OUT_SW_BUF_SZ];
+    #if CFG_FIFO_MUTEX
+    osal_mutex_def_t ep_out_ff_mutex_rd_2; // No need for write mutex as only USB driver writes into FIFO
+    #endif
+  #endif // CFG_TUD_AUDIO > 1 && CFG_TUD_AUDIO_FUNC_2_EP_OUT_SW_BUF_SZ > 0
+
+  #if CFG_TUD_AUDIO > 2 && CFG_TUD_AUDIO_FUNC_3_EP_OUT_SW_BUF_SZ > 0
+    CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN uint8_t audio_ep_out_sw_buf_3[CFG_TUD_AUDIO_FUNC_3_EP_OUT_SW_BUF_SZ];
+    #if CFG_FIFO_MUTEX
+    osal_mutex_def_t ep_out_ff_mutex_rd_3; // No need for write mutex as only USB driver writes into FIFO
+    #endif
+  #endif // CFG_TUD_AUDIO > 2 && CFG_TUD_AUDIO_FUNC_3_EP_OUT_SW_BUF_SZ > 0
 #endif // CFG_TUD_AUDIO_ENABLE_EP_OUT && !CFG_TUD_AUDIO_ENABLE_DECODING
 
 // Linear buffer RX in case:
 // - target MCU is not capable of handling a ring buffer FIFO e.g. no hardware buffer is available or driver is would need to be changed dramatically OR
 // - the software encoding is used - in this case the linear buffers serve as a target memory where logical channels are encoded into
 #if CFG_TUD_AUDIO_ENABLE_EP_OUT && (USE_LINEAR_BUFFER || CFG_TUD_AUDIO_ENABLE_DECODING)
-#if CFG_TUD_AUDIO_FUNC_1_EP_OUT_SZ_MAX > 0
-CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN uint8_t lin_buf_out_1[CFG_TUD_AUDIO_FUNC_1_EP_OUT_SZ_MAX];
-#endif
-#if CFG_TUD_AUDIO > 1 && CFG_TUD_AUDIO_FUNC_2_EP_OUT_SZ_MAX > 0
-CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN uint8_t lin_buf_out_2[CFG_TUD_AUDIO_FUNC_2_EP_OUT_SZ_MAX];
-#endif
-#if CFG_TUD_AUDIO > 2 && CFG_TUD_AUDIO_FUNC_3_EP_OUT_SZ_MAX > 0
-CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN uint8_t lin_buf_out_3[CFG_TUD_AUDIO_FUNC_3_EP_OUT_SZ_MAX];
-#endif
+  #if CFG_TUD_AUDIO_FUNC_1_EP_OUT_SZ_MAX > 0
+    CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN uint8_t lin_buf_out_1[CFG_TUD_AUDIO_FUNC_1_EP_OUT_SZ_MAX];
+  #endif
+
+  #if CFG_TUD_AUDIO > 1 && CFG_TUD_AUDIO_FUNC_2_EP_OUT_SZ_MAX > 0
+    CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN uint8_t lin_buf_out_2[CFG_TUD_AUDIO_FUNC_2_EP_OUT_SZ_MAX];
+  #endif
+
+  #if CFG_TUD_AUDIO > 2 && CFG_TUD_AUDIO_FUNC_3_EP_OUT_SZ_MAX > 0
+    CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN uint8_t lin_buf_out_3[CFG_TUD_AUDIO_FUNC_3_EP_OUT_SZ_MAX];
+  #endif
 #endif // CFG_TUD_AUDIO_ENABLE_EP_OUT && (USE_LINEAR_BUFFER || CFG_TUD_AUDIO_ENABLE_DECODING)
 
 // Control buffers
 CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN uint8_t ctrl_buf_1[CFG_TUD_AUDIO_FUNC_1_CTRL_BUF_SZ];
+
 #if CFG_TUD_AUDIO > 1
 CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN uint8_t ctrl_buf_2[CFG_TUD_AUDIO_FUNC_2_CTRL_BUF_SZ];
 #endif
+
 #if CFG_TUD_AUDIO > 2
 CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN uint8_t ctrl_buf_3[CFG_TUD_AUDIO_FUNC_3_CTRL_BUF_SZ];
 #endif
 
 // Active alternate setting of interfaces
 uint8_t alt_setting_1[CFG_TUD_AUDIO_FUNC_1_N_AS_INT];
+
 #if CFG_TUD_AUDIO > 1 && CFG_TUD_AUDIO_FUNC_2_N_AS_INT > 0
 uint8_t alt_setting_2[CFG_TUD_AUDIO_FUNC_2_N_AS_INT];
 #endif
+
 #if CFG_TUD_AUDIO > 2 && CFG_TUD_AUDIO_FUNC_3_N_AS_INT > 0
 uint8_t alt_setting_3[CFG_TUD_AUDIO_FUNC_3_N_AS_INT];
 #endif
 
 // Software encoding/decoding support FIFOs
 #if CFG_TUD_AUDIO_ENABLE_EP_IN && CFG_TUD_AUDIO_ENABLE_ENCODING
-#if CFG_TUD_AUDIO_FUNC_1_TX_SUPP_SW_FIFO_SZ > 0
-CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN uint8_t tx_supp_ff_buf_1[CFG_TUD_AUDIO_FUNC_1_N_TX_SUPP_SW_FIFO][CFG_TUD_AUDIO_FUNC_1_TX_SUPP_SW_FIFO_SZ];
-tu_fifo_t tx_supp_ff_1[CFG_TUD_AUDIO_FUNC_1_N_TX_SUPP_SW_FIFO];
-#if CFG_FIFO_MUTEX
-osal_mutex_def_t tx_supp_ff_mutex_wr_1[CFG_TUD_AUDIO_FUNC_1_N_TX_SUPP_SW_FIFO];                   // No need for read mutex as only USB driver reads from FIFO
-#endif
-#endif
-#if CFG_TUD_AUDIO > 1 && CFG_TUD_AUDIO_FUNC_2_TX_SUPP_SW_FIFO_SZ > 0
-CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN uint8_t tx_supp_ff_buf_2[CFG_TUD_AUDIO_FUNC_2_N_TX_SUPP_SW_FIFO][CFG_TUD_AUDIO_FUNC_2_TX_SUPP_SW_FIFO_SZ];
-tu_fifo_t tx_supp_ff_2[CFG_TUD_AUDIO_FUNC_2_N_TX_SUPP_SW_FIFO];
-#if CFG_FIFO_MUTEX
-osal_mutex_def_t tx_supp_ff_mutex_wr_2[CFG_TUD_AUDIO_FUNC_2_N_TX_SUPP_SW_FIFO];                   // No need for read mutex as only USB driver reads from FIFO
-#endif
-#endif
-#if CFG_TUD_AUDIO > 2 && CFG_TUD_AUDIO_FUNC_3_TX_SUPP_SW_FIFO_SZ > 0
-CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN uint8_t tx_supp_ff_buf_3[CFG_TUD_AUDIO_FUNC_3_N_TX_SUPP_SW_FIFO][CFG_TUD_AUDIO_FUNC_3_TX_SUPP_SW_FIFO_SZ];
-tu_fifo_t tx_supp_ff_3[CFG_TUD_AUDIO_FUNC_3_N_TX_SUPP_SW_FIFO];
-#if CFG_FIFO_MUTEX
-osal_mutex_def_t tx_supp_ff_mutex_wr_3[CFG_TUD_AUDIO_FUNC_3_N_TX_SUPP_SW_FIFO];                   // No need for read mutex as only USB driver reads from FIFO
-#endif
-#endif
+  #if CFG_TUD_AUDIO_FUNC_1_TX_SUPP_SW_FIFO_SZ > 0
+    CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN uint8_t tx_supp_ff_buf_1[CFG_TUD_AUDIO_FUNC_1_N_TX_SUPP_SW_FIFO][CFG_TUD_AUDIO_FUNC_1_TX_SUPP_SW_FIFO_SZ];
+    tu_fifo_t tx_supp_ff_1[CFG_TUD_AUDIO_FUNC_1_N_TX_SUPP_SW_FIFO];
+    #if CFG_FIFO_MUTEX
+    osal_mutex_def_t tx_supp_ff_mutex_wr_1[CFG_TUD_AUDIO_FUNC_1_N_TX_SUPP_SW_FIFO]; // No need for read mutex as only USB driver reads from FIFO
+    #endif
+  #endif
+
+  #if CFG_TUD_AUDIO > 1 && CFG_TUD_AUDIO_FUNC_2_TX_SUPP_SW_FIFO_SZ > 0
+    CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN uint8_t tx_supp_ff_buf_2[CFG_TUD_AUDIO_FUNC_2_N_TX_SUPP_SW_FIFO][CFG_TUD_AUDIO_FUNC_2_TX_SUPP_SW_FIFO_SZ];
+    tu_fifo_t tx_supp_ff_2[CFG_TUD_AUDIO_FUNC_2_N_TX_SUPP_SW_FIFO];
+    #if CFG_FIFO_MUTEX
+    osal_mutex_def_t tx_supp_ff_mutex_wr_2[CFG_TUD_AUDIO_FUNC_2_N_TX_SUPP_SW_FIFO]; // No need for read mutex as only USB driver reads from FIFO
+    #endif
+  #endif
+
+  #if CFG_TUD_AUDIO > 2 && CFG_TUD_AUDIO_FUNC_3_TX_SUPP_SW_FIFO_SZ > 0
+    CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN uint8_t tx_supp_ff_buf_3[CFG_TUD_AUDIO_FUNC_3_N_TX_SUPP_SW_FIFO][CFG_TUD_AUDIO_FUNC_3_TX_SUPP_SW_FIFO_SZ];
+    tu_fifo_t tx_supp_ff_3[CFG_TUD_AUDIO_FUNC_3_N_TX_SUPP_SW_FIFO];
+    #if CFG_FIFO_MUTEX
+    osal_mutex_def_t tx_supp_ff_mutex_wr_3[CFG_TUD_AUDIO_FUNC_3_N_TX_SUPP_SW_FIFO]; // No need for read mutex as only USB driver reads from FIFO
+    #endif
+  #endif
 #endif
 
 #if CFG_TUD_AUDIO_ENABLE_EP_OUT && CFG_TUD_AUDIO_ENABLE_DECODING
-#if CFG_TUD_AUDIO_FUNC_1_RX_SUPP_SW_FIFO_SZ > 0
-CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN uint8_t rx_supp_ff_buf_1[CFG_TUD_AUDIO_FUNC_1_N_RX_SUPP_SW_FIFO][CFG_TUD_AUDIO_FUNC_1_RX_SUPP_SW_FIFO_SZ];
-tu_fifo_t rx_supp_ff_1[CFG_TUD_AUDIO_FUNC_1_N_RX_SUPP_SW_FIFO];
-#if CFG_FIFO_MUTEX
-osal_mutex_def_t rx_supp_ff_mutex_rd_1[CFG_TUD_AUDIO_FUNC_1_N_RX_SUPP_SW_FIFO];                   // No need for write mutex as only USB driver writes into FIFO
-#endif
-#endif
-#if CFG_TUD_AUDIO > 1 && CFG_TUD_AUDIO_FUNC_2_RX_SUPP_SW_FIFO_SZ > 0
-CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN uint8_t rx_supp_ff_buf_2[CFG_TUD_AUDIO_FUNC_2_N_RX_SUPP_SW_FIFO][CFG_TUD_AUDIO_FUNC_2_RX_SUPP_SW_FIFO_SZ];
-tu_fifo_t rx_supp_ff_2[CFG_TUD_AUDIO_FUNC_2_N_RX_SUPP_SW_FIFO];
-#if CFG_FIFO_MUTEX
-osal_mutex_def_t rx_supp_ff_mutex_rd_2[CFG_TUD_AUDIO_FUNC_2_N_RX_SUPP_SW_FIFO];                   // No need for write mutex as only USB driver writes into FIFO
-#endif
-#endif
-#if CFG_TUD_AUDIO > 2 && CFG_TUD_AUDIO_FUNC_3_RX_SUPP_SW_FIFO_SZ > 0
-CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN uint8_t rx_supp_ff_buf_3[CFG_TUD_AUDIO_FUNC_3_N_RX_SUPP_SW_FIFO][CFG_TUD_AUDIO_FUNC_3_RX_SUPP_SW_FIFO_SZ];
-tu_fifo_t rx_supp_ff_3[CFG_TUD_AUDIO_FUNC_3_N_RX_SUPP_SW_FIFO];
-#if CFG_FIFO_MUTEX
-osal_mutex_def_t rx_supp_ff_mutex_rd_3[CFG_TUD_AUDIO_FUNC_3_N_RX_SUPP_SW_FIFO];                   // No need for write mutex as only USB driver writes into FIFO
-#endif
-#endif
+  #if CFG_TUD_AUDIO_FUNC_1_RX_SUPP_SW_FIFO_SZ > 0
+    CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN uint8_t rx_supp_ff_buf_1[CFG_TUD_AUDIO_FUNC_1_N_RX_SUPP_SW_FIFO][CFG_TUD_AUDIO_FUNC_1_RX_SUPP_SW_FIFO_SZ];
+    tu_fifo_t rx_supp_ff_1[CFG_TUD_AUDIO_FUNC_1_N_RX_SUPP_SW_FIFO];
+    #if CFG_FIFO_MUTEX
+    osal_mutex_def_t rx_supp_ff_mutex_rd_1[CFG_TUD_AUDIO_FUNC_1_N_RX_SUPP_SW_FIFO]; // No need for write mutex as only USB driver writes into FIFO
+    #endif
+  #endif
+
+  #if CFG_TUD_AUDIO > 1 && CFG_TUD_AUDIO_FUNC_2_RX_SUPP_SW_FIFO_SZ > 0
+    CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN uint8_t rx_supp_ff_buf_2[CFG_TUD_AUDIO_FUNC_2_N_RX_SUPP_SW_FIFO][CFG_TUD_AUDIO_FUNC_2_RX_SUPP_SW_FIFO_SZ];
+    tu_fifo_t rx_supp_ff_2[CFG_TUD_AUDIO_FUNC_2_N_RX_SUPP_SW_FIFO];
+    #if CFG_FIFO_MUTEX
+    osal_mutex_def_t rx_supp_ff_mutex_rd_2[CFG_TUD_AUDIO_FUNC_2_N_RX_SUPP_SW_FIFO]; // No need for write mutex as only USB driver writes into FIFO
+    #endif
+  #endif
+
+  #if CFG_TUD_AUDIO > 2 && CFG_TUD_AUDIO_FUNC_3_RX_SUPP_SW_FIFO_SZ > 0
+    CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN uint8_t rx_supp_ff_buf_3[CFG_TUD_AUDIO_FUNC_3_N_RX_SUPP_SW_FIFO][CFG_TUD_AUDIO_FUNC_3_RX_SUPP_SW_FIFO_SZ];
+    tu_fifo_t rx_supp_ff_3[CFG_TUD_AUDIO_FUNC_3_N_RX_SUPP_SW_FIFO];
+    #if CFG_FIFO_MUTEX
+    osal_mutex_def_t rx_supp_ff_mutex_rd_3[CFG_TUD_AUDIO_FUNC_3_N_RX_SUPP_SW_FIFO]; // No need for write mutex as only USB driver writes into FIFO
+    #endif
+  #endif
 #endif
 
 typedef struct
@@ -305,9 +311,35 @@ typedef struct
 #endif
 
 #if CFG_TUD_AUDIO_ENABLE_FEEDBACK_EP
-  uint32_t fb_val;                                                              // Feedback value for asynchronous mode (in 16.16 format).
-#endif
+  struct {
+    CFG_TUSB_MEM_ALIGN uint32_t value;  // Feedback value for asynchronous mode (in 16.16 format).
+    uint32_t min_value;   // min value according to UAC2 FMT-2.0 section 2.3.1.1.
+    uint32_t max_value;   // max value according to UAC2 FMT-2.0 section 2.3.1.1.
+
+    uint8_t frame_shift;  // bInterval-1 in unit of frame (FS), micro-frame (HS)
+    uint8_t compute_method;
+
+    union {
+      uint8_t power_of_2; // pre-computed power of 2 shift
+      float float_const;  // pre-computed float constant
+
+      struct {
+        uint32_t sample_freq;
+        uint32_t mclk_freq;
+      }fixed;
+
+#if 0 // implement later
+      struct {
+        uint32_t nominal_value;
+        uint32_t threshold_bytes;
+      }fifo_count;
 #endif
+    }compute;
+
+  } feedback;
+#endif // CFG_TUD_AUDIO_ENABLE_FEEDBACK_EP
+
+#endif // CFG_TUD_AUDIO_ENABLE_EP_OUT
 
 #if CFG_TUD_AUDIO_ENABLE_EP_IN && !CFG_TUD_AUDIO_ENABLE_ENCODING
   tu_fifo_t ep_in_ff;
@@ -315,7 +347,7 @@ typedef struct
 
   // Audio control interrupt buffer - no FIFO - 6 Bytes according to UAC 2 specification (p. 74)
 #if CFG_TUD_AUDIO_INT_CTR_EPSIZE_IN
-  CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN uint8_t ep_int_ctr_buf[CFG_TUD_AUDIO_INT_CTR_EP_IN_SW_BUFFER_SIZE];
+  CFG_TUSB_MEM_ALIGN uint8_t ep_int_ctr_buf[CFG_TUD_AUDIO_INT_CTR_EP_IN_SW_BUFFER_SIZE];
 #endif
 
   // Decoding parameters - parameters are set when alternate AS interface is set by host
@@ -421,6 +453,10 @@ static inline uint8_t tu_desc_subtype(void const* desc)
 }
 #endif
 
+#if CFG_TUD_AUDIO_ENABLE_EP_OUT && CFG_TUD_AUDIO_ENABLE_FEEDBACK_EP
+static bool set_fb_params_freq(audiod_function_t* audio, uint32_t sample_freq, uint32_t mclk_freq);
+#endif
+
 bool tud_audio_n_mounted(uint8_t func_id)
 {
   TU_VERIFY(func_id < CFG_TUD_AUDIO);
@@ -511,7 +547,7 @@ tu_fifo_t* tud_audio_n_get_rx_support_ff(uint8_t func_id, uint8_t ff_idx)
 
 static bool audiod_rx_done_cb(uint8_t rhport, audiod_function_t* audio, uint16_t n_bytes_received)
 {
-  uint8_t idxItf;
+  uint8_t idxItf = 0;
   uint8_t const *dummy2;
   uint8_t idx_audio_fct = 0;
 
@@ -522,7 +558,10 @@ static bool audiod_rx_done_cb(uint8_t rhport, audiod_function_t* audio, uint16_t
   }
 
   // Call a weak callback here - a possibility for user to get informed an audio packet was received and data gets now loaded into EP FIFO (or decoded into support RX software FIFO)
-  if (tud_audio_rx_done_pre_read_cb) TU_VERIFY(tud_audio_rx_done_pre_read_cb(rhport, n_bytes_received, idx_audio_fct, audio->ep_out, audio->alt_setting[idxItf]));
+  if (tud_audio_rx_done_pre_read_cb)
+  {
+    TU_VERIFY(tud_audio_rx_done_pre_read_cb(rhport, n_bytes_received, idx_audio_fct, audio->ep_out, audio->alt_setting[idxItf]));
+  }
 
 #if CFG_TUD_AUDIO_ENABLE_DECODING && CFG_TUD_AUDIO_ENABLE_EP_OUT
 
@@ -536,7 +575,7 @@ static bool audiod_rx_done_cb(uint8_t rhport, audiod_function_t* audio, uint16_t
 
     case AUDIO_FORMAT_TYPE_I:
 
-      switch (audio->format_type_I_tx)
+      switch (audio->format_type_I_rx)
       {
         case AUDIO_DATA_FORMAT_TYPE_I_PCM:
           TU_VERIFY(audiod_decode_type_I_pcm(rhport, audio, n_bytes_received));
@@ -576,7 +615,10 @@ static bool audiod_rx_done_cb(uint8_t rhport, audiod_function_t* audio, uint16_t
 #endif
 
   // Call a weak callback here - a possibility for user to get informed decoding was completed
-  if (tud_audio_rx_done_post_read_cb) TU_VERIFY(tud_audio_rx_done_post_read_cb(rhport, n_bytes_received, idx_audio_fct, audio->ep_out, audio->alt_setting[idxItf]));
+  if (tud_audio_rx_done_post_read_cb)
+  {
+    TU_VERIFY(tud_audio_rx_done_post_read_cb(rhport, n_bytes_received, idx_audio_fct, audio->ep_out, audio->alt_setting[idxItf]));
+  }
 
   return true;
 }
@@ -787,10 +829,7 @@ uint16_t tud_audio_int_ctr_n_write(uint8_t func_id, uint8_t const* buffer, uint1
   // We write directly into the EP's buffer - abort if previous transfer not complete
   TU_VERIFY(!usbd_edpt_busy(_audiod_fct[func_id].rhport, _audiod_fct[func_id].ep_int_ctr));
 
-  // Check length
-  TU_VERIFY(len <= CFG_TUD_AUDIO_INT_CTR_EP_IN_SW_BUFFER_SIZE);
-
-  memcpy(_audiod_fct[func_id].ep_int_ctr_buf, buffer, len);
+  TU_VERIFY(tu_memcpy_s(_audiod_fct[func_id].ep_int_ctr_buf, CFG_TUD_AUDIO_INT_CTR_EP_IN_SW_BUFFER_SIZE,  buffer, len)==0);
 
   // Schedule transmit
   TU_VERIFY(usbd_edpt_xfer(_audiod_fct[func_id].rhport, _audiod_fct[func_id].ep_int_ctr, _audiod_fct[func_id].ep_int_ctr_buf, len));
@@ -1039,7 +1078,7 @@ static uint16_t audiod_encode_type_I_pcm(uint8_t rhport, audiod_function_t* audi
 #if CFG_TUD_AUDIO_ENABLE_EP_OUT && CFG_TUD_AUDIO_ENABLE_FEEDBACK_EP
 static inline bool audiod_fb_send(uint8_t rhport, audiod_function_t *audio)
 {
-  return usbd_edpt_xfer(rhport, audio->ep_fb, (uint8_t *) &audio->fb_val, 4);
+  return usbd_edpt_xfer(rhport, audio->ep_fb, (uint8_t *) &audio->feedback.value, 4);
 }
 #endif
 
@@ -1438,6 +1477,83 @@ uint16_t audiod_open(uint8_t rhport, tusb_desc_interface_t const * itf_desc, uin
 #endif
       }
 
+#if USE_ISO_EP_ALLOCATION
+  #if CFG_TUD_AUDIO_ENABLE_EP_IN
+      uint8_t  ep_in = 0;
+      uint16_t ep_in_size = 0;
+  #endif
+
+  #if CFG_TUD_AUDIO_ENABLE_EP_OUT
+      uint8_t  ep_out = 0;
+      uint16_t ep_out_size = 0;
+  #endif
+
+  #if CFG_TUD_AUDIO_ENABLE_FEEDBACK_EP
+      uint8_t ep_fb = 0;
+  #endif
+
+      uint8_t const *p_desc = _audiod_fct[i].p_desc;
+      uint8_t const *p_desc_end = p_desc + _audiod_fct[i].desc_length - TUD_AUDIO_DESC_IAD_LEN;
+      while (p_desc < p_desc_end)
+      {
+        if (tu_desc_type(p_desc) == TUSB_DESC_ENDPOINT)
+        {
+          tusb_desc_endpoint_t const *desc_ep = (tusb_desc_endpoint_t const *) p_desc;
+          if (desc_ep->bmAttributes.xfer == TUSB_XFER_ISOCHRONOUS)
+          {
+  #if CFG_TUD_AUDIO_ENABLE_FEEDBACK_EP
+            // Explicit feedback EP
+            if (desc_ep->bmAttributes.usage == 1)
+            {
+              ep_fb = desc_ep->bEndpointAddress;
+            }
+  #endif
+            // Data EP
+            if (desc_ep->bmAttributes.usage == 0)
+            {
+              if (tu_edpt_dir(desc_ep->bEndpointAddress) == TUSB_DIR_IN)
+              {
+  #if CFG_TUD_AUDIO_ENABLE_EP_IN
+                ep_in = desc_ep->bEndpointAddress;
+                ep_in_size = TU_MAX(tu_edpt_packet_size(desc_ep), ep_in_size);
+  #endif
+              } else
+              {
+  #if CFG_TUD_AUDIO_ENABLE_EP_OUT
+                ep_out = desc_ep->bEndpointAddress;
+                ep_out_size = TU_MAX(tu_edpt_packet_size(desc_ep), ep_out_size);
+  #endif
+              }
+            }
+
+          }
+        }
+        p_desc = tu_desc_next(p_desc);
+      }
+
+  #if CFG_TUD_AUDIO_ENABLE_EP_IN
+      if (ep_in)
+      {
+        usbd_edpt_iso_alloc(rhport, ep_in, ep_in_size);
+      }
+  #endif
+
+  #if CFG_TUD_AUDIO_ENABLE_EP_OUT
+      if (ep_out)
+      {
+        usbd_edpt_iso_alloc(rhport, ep_out, ep_out_size);
+      }
+  #endif
+
+  #if CFG_TUD_AUDIO_ENABLE_FEEDBACK_EP
+      if (ep_fb)
+      {
+        usbd_edpt_iso_alloc(rhport, ep_fb, 4);
+      }
+  #endif
+
+#endif // USE_ISO_EP_ALLOCATION
+
       break;
     }
   }
@@ -1499,41 +1615,45 @@ static bool audiod_set_interface(uint8_t rhport, tusb_control_request_t const *
   if (audio->ep_in_as_intf_num == itf)
   {
     audio->ep_in_as_intf_num = 0;
+  #if !USE_ISO_EP_ALLOCATION
     usbd_edpt_close(rhport, audio->ep_in);
+  #endif
 
     // Clear FIFOs, since data is no longer valid
-#if !CFG_TUD_AUDIO_ENABLE_ENCODING
+  #if !CFG_TUD_AUDIO_ENABLE_ENCODING
     tu_fifo_clear(&audio->ep_in_ff);
-#else
+  #else
     for (uint8_t cnt = 0; cnt < audio->n_tx_supp_ff; cnt++)
     {
       tu_fifo_clear(&audio->tx_supp_ff[cnt]);
     }
-#endif
-    
+  #endif
+
     // Invoke callback - can be used to stop data sampling
     if (tud_audio_set_itf_close_EP_cb) TU_VERIFY(tud_audio_set_itf_close_EP_cb(rhport, p_request));
 
     audio->ep_in = 0;                           // Necessary?
 
   }
-#endif
+#endif // CFG_TUD_AUDIO_ENABLE_EP_IN
 
 #if CFG_TUD_AUDIO_ENABLE_EP_OUT
   if (audio->ep_out_as_intf_num == itf)
   {
     audio->ep_out_as_intf_num = 0;
+  #if !USE_ISO_EP_ALLOCATION
     usbd_edpt_close(rhport, audio->ep_out);
+  #endif
 
     // Clear FIFOs, since data is no longer valid
-#if !CFG_TUD_AUDIO_ENABLE_DECODING
+  #if !CFG_TUD_AUDIO_ENABLE_DECODING
     tu_fifo_clear(&audio->ep_out_ff);
-#else
+  #else
     for (uint8_t cnt = 0; cnt < audio->n_rx_supp_ff; cnt++)
     {
       tu_fifo_clear(&audio->rx_supp_ff[cnt]);
     }
-#endif
+  #endif
 
     // Invoke callback - can be used to stop data sampling
     if (tud_audio_set_itf_close_EP_cb) TU_VERIFY(tud_audio_set_itf_close_EP_cb(rhport, p_request));
@@ -1541,12 +1661,15 @@ static bool audiod_set_interface(uint8_t rhport, tusb_control_request_t const *
     audio->ep_out = 0;                          // Necessary?
 
     // Close corresponding feedback EP
-#if CFG_TUD_AUDIO_ENABLE_FEEDBACK_EP
+  #if CFG_TUD_AUDIO_ENABLE_FEEDBACK_EP
+    #if !USE_ISO_EP_ALLOCATION
     usbd_edpt_close(rhport, audio->ep_fb);
-    audio->ep_fb = 0;                           // Necessary?
-#endif
+    #endif
+    audio->ep_fb = 0;
+    tu_memclr(&audio->feedback, sizeof(audio->feedback));
+  #endif
   }
-#endif
+#endif // CFG_TUD_AUDIO_ENABLE_EP_OUT
 
   // Save current alternative interface setting
   audio->alt_setting[idxItf] = alt;
@@ -1571,8 +1694,11 @@ static bool audiod_set_interface(uint8_t rhport, tusb_control_request_t const *
         if (tu_desc_type(p_desc) == TUSB_DESC_ENDPOINT)
         {
           tusb_desc_endpoint_t const* desc_ep = (tusb_desc_endpoint_t const *) p_desc;
+#if USE_ISO_EP_ALLOCATION
+          TU_ASSERT(usbd_edpt_iso_activate(rhport, desc_ep));
+#else
           TU_ASSERT(usbd_edpt_open(rhport, desc_ep));
-
+#endif
           uint8_t const ep_addr = desc_ep->bEndpointAddress;
 
           //TODO: We need to set EP non busy since this is not taken care of right now in ep_close() - THIS IS A WORKAROUND!
@@ -1587,23 +1713,20 @@ static bool audiod_set_interface(uint8_t rhport, tusb_control_request_t const *
             audio->ep_in_sz = tu_edpt_packet_size(desc_ep);
 
             // If software encoding is enabled, parse for the corresponding parameters - doing this here means only AS interfaces with EPs get scanned for parameters
-#if CFG_TUD_AUDIO_ENABLE_ENCODING
+  #if CFG_TUD_AUDIO_ENABLE_ENCODING
             audiod_parse_for_AS_params(audio, p_desc_parse_for_params, p_desc_end, itf);
 
             // Reconfigure size of support FIFOs - this is necessary to avoid samples to get split in case of a wrap
-#if CFG_TUD_AUDIO_ENABLE_TYPE_I_ENCODING
-            const uint16_t active_fifo_depth = (audio->tx_supp_ff_sz_max / audio->n_bytes_per_sampe_tx) * audio->n_bytes_per_sampe_tx;
+    #if CFG_TUD_AUDIO_ENABLE_TYPE_I_ENCODING
+            const uint16_t active_fifo_depth = (uint16_t) ((audio->tx_supp_ff_sz_max / audio->n_bytes_per_sampe_tx) * audio->n_bytes_per_sampe_tx);
             for (uint8_t cnt = 0; cnt < audio->n_tx_supp_ff; cnt++)
             {
               tu_fifo_config(&audio->tx_supp_ff[cnt], audio->tx_supp_ff[cnt].buffer, active_fifo_depth, 1, true);
             }
             audio->n_ff_used_tx = audio->n_channels_tx / audio->n_channels_per_ff_tx;
             TU_ASSERT( audio->n_ff_used_tx <= audio->n_tx_supp_ff );
-#endif
-
-#endif
-            // Invoke callback - can be used to trigger data sampling if not already running
-            if (tud_audio_set_itf_cb) TU_VERIFY(tud_audio_set_itf_cb(rhport, p_request));
+    #endif
+  #endif
 
             // Schedule first transmit if alternate interface is not zero i.e. streaming is disabled - in case no sample data is available a ZLP is loaded
             // It is necessary to trigger this here since the refill is done with an RX FIFO empty interrupt which can only trigger if something was in there
@@ -1620,11 +1743,11 @@ static bool audiod_set_interface(uint8_t rhport, tusb_control_request_t const *
             audio->ep_out_as_intf_num = itf;
             audio->ep_out_sz = tu_edpt_packet_size(desc_ep);
 
-#if CFG_TUD_AUDIO_ENABLE_DECODING
+  #if CFG_TUD_AUDIO_ENABLE_DECODING
             audiod_parse_for_AS_params(audio, p_desc_parse_for_params, p_desc_end, itf);
 
             // Reconfigure size of support FIFOs - this is necessary to avoid samples to get split in case of a wrap
-#if CFG_TUD_AUDIO_ENABLE_TYPE_I_DECODING
+    #if CFG_TUD_AUDIO_ENABLE_TYPE_I_DECODING
             const uint16_t active_fifo_depth = (audio->rx_supp_ff_sz_max / audio->n_bytes_per_sampe_rx) * audio->n_bytes_per_sampe_rx;
             for (uint8_t cnt = 0; cnt < audio->n_rx_supp_ff; cnt++)
             {
@@ -1632,39 +1755,27 @@ static bool audiod_set_interface(uint8_t rhport, tusb_control_request_t const *
             }
             audio->n_ff_used_rx = audio->n_channels_rx / audio->n_channels_per_ff_rx;
             TU_ASSERT( audio->n_ff_used_rx <= audio->n_rx_supp_ff );
-#endif
-#endif
+    #endif
+  #endif
 
-#if CFG_TUD_AUDIO_ENABLE_FEEDBACK_EP
-            // In case of asynchronous EP, call Cb after ep_fb is set
-            if ( !(desc_ep->bmAttributes.sync == 0x01 && audio->ep_fb == 0) )
-            {
-              if (tud_audio_set_itf_cb) TU_VERIFY(tud_audio_set_itf_cb(rhport, p_request));
-            }
-#else
-            // Invoke callback
-            if (tud_audio_set_itf_cb) TU_VERIFY(tud_audio_set_itf_cb(rhport, p_request));
-#endif
             // Prepare for incoming data
-#if USE_LINEAR_BUFFER_RX
+  #if USE_LINEAR_BUFFER_RX
             TU_VERIFY(usbd_edpt_xfer(rhport, audio->ep_out, audio->lin_buf_out, audio->ep_out_sz), false);
-#else
+  #else
             TU_VERIFY(usbd_edpt_xfer_fifo(rhport, audio->ep_out, &audio->ep_out_ff, audio->ep_out_sz), false);
-#endif
+  #endif
           }
 
-#if CFG_TUD_AUDIO_ENABLE_FEEDBACK_EP
+  #if CFG_TUD_AUDIO_ENABLE_FEEDBACK_EP
           if (tu_edpt_dir(ep_addr) == TUSB_DIR_IN && desc_ep->bmAttributes.usage == 1)   // Check if usage is explicit data feedback
           {
             audio->ep_fb = ep_addr;
+            audio->feedback.frame_shift = desc_ep->bInterval -1;
 
-            // Invoke callback after ep_out is set
-            if (audio->ep_out != 0)
-            {
-              if (tud_audio_set_itf_cb) TU_VERIFY(tud_audio_set_itf_cb(rhport, p_request));
-            }
+            // Enable SOF interrupt if callback is implemented
+            if (tud_audio_feedback_interval_isr) usbd_sof_enable(rhport, true);
           }
-#endif
+  #endif
 #endif // CFG_TUD_AUDIO_ENABLE_EP_OUT
 
           foundEPs += 1;
@@ -1674,6 +1785,49 @@ static bool audiod_set_interface(uint8_t rhport, tusb_control_request_t const *
 
       TU_VERIFY(foundEPs == nEps);
 
+      // Invoke one callback for a final set interface
+      if (tud_audio_set_itf_cb) TU_VERIFY(tud_audio_set_itf_cb(rhport, p_request));
+
+#if CFG_TUD_AUDIO_ENABLE_FEEDBACK_EP
+      // Prepare feedback computation if callback is available
+      if (tud_audio_feedback_params_cb)
+      {
+        audio_feedback_params_t fb_param;
+
+        tud_audio_feedback_params_cb(func_id, alt, &fb_param);
+        audio->feedback.compute_method = fb_param.method;
+
+        // Minimal/Maximum value in 16.16 format for full speed (1ms per frame) or high speed (125 us per frame)
+        uint32_t const frame_div  = (TUSB_SPEED_FULL == tud_speed_get()) ? 1000 : 8000;
+        audio->feedback.min_value = (fb_param.sample_freq/frame_div - 1) << 16;
+        audio->feedback.max_value = (fb_param.sample_freq/frame_div + 1) << 16;
+
+        switch(fb_param.method)
+        {
+          case AUDIO_FEEDBACK_METHOD_FREQUENCY_FIXED:
+          case AUDIO_FEEDBACK_METHOD_FREQUENCY_FLOAT:
+          case AUDIO_FEEDBACK_METHOD_FREQUENCY_POWER_OF_2:
+            set_fb_params_freq(audio, fb_param.sample_freq, fb_param.frequency.mclk_freq);
+          break;
+
+          #if 0 // implement later
+          case AUDIO_FEEDBACK_METHOD_FIFO_COUNT:
+          {
+            uint64_t fb64 = ((uint64_t) fb_param.sample_freq) << 16;
+            audio->feedback.compute.fifo_count.nominal_value = (uint32_t) (fb64 / frame_div);
+            audio->feedback.compute.fifo_count.threshold_bytes = fb_param.fifo_count.threshold_bytes;
+
+            tud_audio_fb_set(audio->feedback.compute.fifo_count.nominal_value);
+          }
+          break;
+          #endif
+
+          // nothing to do
+          default: break;
+        }
+      }
+#endif // CFG_TUD_AUDIO_ENABLE_FEEDBACK_EP
+
       // We are done - abort loop
       break;
     }
@@ -1682,6 +1836,20 @@ static bool audiod_set_interface(uint8_t rhport, tusb_control_request_t const *
     p_desc = tu_desc_next(p_desc);
   }
 
+#if CFG_TUD_AUDIO_ENABLE_FEEDBACK_EP
+  // Disable SOF interrupt if no driver has any enabled feedback EP
+  bool disable = true;
+  for(uint8_t i=0; i < CFG_TUD_AUDIO; i++)
+  {
+    if (_audiod_fct[i].ep_fb != 0)
+    {
+      disable = false;
+      break;
+    }
+  }
+  if (disable) usbd_sof_enable(rhport, false);
+#endif
+
   tud_control_status(rhport, p_request);
 
   return true;
@@ -1898,14 +2066,14 @@ bool audiod_xfer_cb(uint8_t rhport, uint8_t ep_addr, xfer_result_t result, uint3
   (void) xferred_bytes;
 
   // Search for interface belonging to given end point address and proceed as required
-  uint8_t func_id;
-  for (func_id = 0; func_id < CFG_TUD_AUDIO; func_id++)
+  for (uint8_t func_id = 0; func_id < CFG_TUD_AUDIO; func_id++)
   {
+    audiod_function_t* audio = &_audiod_fct[func_id];
 
 #if CFG_TUD_AUDIO_INT_CTR_EPSIZE_IN
 
     // Data transmission of control interrupt finished
-    if (_audiod_fct[func_id].ep_int_ctr == ep_addr)
+    if (audio->ep_int_ctr == ep_addr)
     {
       // According to USB2 specification, maximum payload of interrupt EP is 8 bytes on low speed, 64 bytes on full speed, and 1024 bytes on high speed (but only if an alternate interface other than 0 is used - see specification p. 49)
       // In case there is nothing to send we have to return a NAK - this is taken care of by PHY ???
@@ -1922,7 +2090,7 @@ bool audiod_xfer_cb(uint8_t rhport, uint8_t ep_addr, xfer_result_t result, uint3
 #if CFG_TUD_AUDIO_ENABLE_EP_IN
 
     // Data transmission of audio packet finished
-    if (_audiod_fct[func_id].ep_in == ep_addr && _audiod_fct[func_id].alt_setting != 0)
+    if (audio->ep_in == ep_addr && audio->alt_setting != 0)
     {
       // USB 2.0, section 5.6.4, third paragraph, states "An isochronous endpoint must specify its required bus access period. However, an isochronous endpoint must be prepared to handle poll rates faster than the one specified."
       // That paragraph goes on to say "An isochronous IN endpoint must return a zero-length packet whenever data is requested at a faster interval than the specified interval and data is not available."
@@ -1933,7 +2101,7 @@ bool audiod_xfer_cb(uint8_t rhport, uint8_t ep_addr, xfer_result_t result, uint3
       // This is the only place where we can fill something into the EPs buffer!
 
       // Load new data
-      TU_VERIFY(audiod_tx_done_cb(rhport, &_audiod_fct[func_id]));
+      TU_VERIFY(audiod_tx_done_cb(rhport, audio));
 
       // Transmission of ZLP is done by audiod_tx_done_cb()
       return true;
@@ -1943,24 +2111,24 @@ bool audiod_xfer_cb(uint8_t rhport, uint8_t ep_addr, xfer_result_t result, uint3
 #if CFG_TUD_AUDIO_ENABLE_EP_OUT
 
     // New audio packet received
-    if (_audiod_fct[func_id].ep_out == ep_addr)
+    if (audio->ep_out == ep_addr)
     {
-      TU_VERIFY(audiod_rx_done_cb(rhport, &_audiod_fct[func_id], (uint16_t) xferred_bytes));
+      TU_VERIFY(audiod_rx_done_cb(rhport, audio, (uint16_t) xferred_bytes));
       return true;
     }
 
 
 #if CFG_TUD_AUDIO_ENABLE_FEEDBACK_EP
     // Transmission of feedback EP finished
-    if (_audiod_fct[func_id].ep_fb == ep_addr)
+    if (audio->ep_fb == ep_addr)
     {
-      if (tud_audio_fb_done_cb) TU_VERIFY(tud_audio_fb_done_cb(rhport));
+      if (tud_audio_fb_done_cb) tud_audio_fb_done_cb(func_id);
 
-      // Schedule a transmit with the new value if EP is not busy 
-      if (!usbd_edpt_busy(rhport, _audiod_fct[func_id].ep_fb))
+      // Schedule a transmit with the new value if EP is not busy
+      if (!usbd_edpt_busy(rhport, audio->ep_fb))
       {
         // Schedule next transmission - value is changed bytud_audio_n_fb_set() in the meantime or the old value gets sent
-        return audiod_fb_send(rhport, &_audiod_fct[func_id]);
+        return audiod_fb_send(rhport, audio);
       }
     }
 #endif
@@ -1970,6 +2138,111 @@ bool audiod_xfer_cb(uint8_t rhport, uint8_t ep_addr, xfer_result_t result, uint3
   return false;
 }
 
+#if CFG_TUD_AUDIO_ENABLE_EP_OUT && CFG_TUD_AUDIO_ENABLE_FEEDBACK_EP
+
+static bool set_fb_params_freq(audiod_function_t* audio, uint32_t sample_freq, uint32_t mclk_freq)
+{
+  // Check if frame interval is within sane limits
+  // The interval value n_frames was taken from the descriptors within audiod_set_interface()
+
+  // n_frames_min is ceil(2^10 * f_s / f_m) for full speed and ceil(2^13 * f_s / f_m) for high speed
+  // this lower limit ensures the measures feedback value has sufficient precision
+  uint32_t const k = (TUSB_SPEED_FULL == tud_speed_get()) ? 10 : 13;
+  uint32_t const n_frame = (1UL << audio->feedback.frame_shift);
+
+  if ( (((1UL << k) * sample_freq / mclk_freq) + 1) > n_frame )
+  {
+    TU_LOG1("  UAC2 feedback interval too small\r\n"); TU_BREAKPOINT(); return false;
+  }
+
+  // Check if parameters really allow for a power of two division
+  if ((mclk_freq % sample_freq) == 0 && tu_is_power_of_two(mclk_freq / sample_freq))
+  {
+    audio->feedback.compute_method     = AUDIO_FEEDBACK_METHOD_FREQUENCY_POWER_OF_2;
+    audio->feedback.compute.power_of_2 = 16 - audio->feedback.frame_shift - tu_log2(mclk_freq / sample_freq);
+  }
+  else if ( audio->feedback.compute_method == AUDIO_FEEDBACK_METHOD_FREQUENCY_FLOAT)
+  {
+    audio->feedback.compute.float_const = (float)sample_freq / mclk_freq * (1UL << (16 - audio->feedback.frame_shift));
+  }
+  else
+  {
+    audio->feedback.compute.fixed.sample_freq = sample_freq;
+    audio->feedback.compute.fixed.mclk_freq = mclk_freq;
+  }
+
+  return true;
+}
+
+uint32_t tud_audio_feedback_update(uint8_t func_id, uint32_t cycles)
+{
+  audiod_function_t* audio = &_audiod_fct[func_id];
+  uint32_t feedback;
+
+  switch (audio->feedback.compute_method)
+  {
+    case AUDIO_FEEDBACK_METHOD_FREQUENCY_POWER_OF_2:
+      feedback = (cycles << audio->feedback.compute.power_of_2);
+    break;
+
+    case AUDIO_FEEDBACK_METHOD_FREQUENCY_FLOAT:
+      feedback = (uint32_t) ((float) cycles * audio->feedback.compute.float_const);
+    break;
+
+    case AUDIO_FEEDBACK_METHOD_FREQUENCY_FIXED:
+    {
+      uint64_t fb64 = (((uint64_t) cycles) * audio->feedback.compute.fixed.sample_freq) << (16 - audio->feedback.frame_shift);
+      feedback = (uint32_t) (fb64 / audio->feedback.compute.fixed.mclk_freq);
+    }
+    break;
+
+    default: return 0;
+  }
+
+  // For Windows: https://docs.microsoft.com/en-us/windows-hardware/drivers/audio/usb-2-0-audio-drivers
+  // The size of isochronous packets created by the device must be within the limits specified in FMT-2.0 section 2.3.1.1.
+  // This means that the deviation of actual packet size from nominal size must not exceed +/- one audio slot
+  // (audio slot = channel count samples).
+  if ( feedback > audio->feedback.max_value ) feedback = audio->feedback.max_value;
+  if ( feedback < audio->feedback.min_value ) feedback = audio->feedback.min_value;
+
+  tud_audio_n_fb_set(func_id, feedback);
+
+  return feedback;
+}
+#endif
+
+TU_ATTR_FAST_FUNC void audiod_sof_isr (uint8_t rhport, uint32_t frame_count)
+{
+  (void) rhport;
+  (void) frame_count;
+
+#if CFG_TUD_AUDIO_ENABLE_EP_OUT && CFG_TUD_AUDIO_ENABLE_FEEDBACK_EP
+  // Determine feedback value - The feedback method is described in 5.12.4.2 of the USB 2.0 spec
+  // Boiled down, the feedback value Ff = n_samples / (micro)frame.
+  // Since an accuracy of less than 1 Sample / second is desired, at least n_frames = ceil(2^K * f_s / f_m) frames need to be measured, where K = 10 for full speed and K = 13 for high speed, f_s is the sampling frequency e.g. 48 kHz and f_m is the cpu clock frequency e.g. 100 MHz (or any other master clock whose clock count is available and locked to f_s)
+  // The update interval in the (4.10.2.1) Feedback Endpoint Descriptor must be less or equal to 2^(K - P), where P = min( ceil(log2(f_m / f_s)), K)
+  // feedback = n_cycles / n_frames * f_s / f_m in 16.16 format, where n_cycles are the number of main clock cycles within fb_n_frames
+
+  // Iterate over audio functions and set feedback value
+  for(uint8_t i=0; i < CFG_TUD_AUDIO; i++)
+  {
+    audiod_function_t* audio = &_audiod_fct[i];
+
+    if (audio->ep_fb != 0)
+    {
+      // HS shift need to be adjusted since SOF event is generated for frame only
+      uint8_t const hs_adjust = (TUSB_SPEED_HIGH == tud_speed_get()) ? 3 : 0;
+      uint32_t const interval = 1UL << (audio->feedback.frame_shift - hs_adjust);
+      if ( 0 == (frame_count & (interval-1)) )
+      {
+        if(tud_audio_feedback_interval_isr) tud_audio_feedback_interval_isr(i, frame_count, audio->feedback.frame_shift);
+      }
+    }
+  }
+#endif // CFG_TUD_AUDIO_ENABLE_EP_OUT && CFG_TUD_AUDIO_ENABLE_FEEDBACK_EP
+}
+
 bool tud_audio_buffer_and_schedule_control_xfer(uint8_t rhport, tusb_control_request_t const * p_request, void* data, uint16_t len)
 {
   // Handles only sending of data not receiving
@@ -2017,7 +2290,7 @@ bool tud_audio_buffer_and_schedule_control_xfer(uint8_t rhport, tusb_control_req
   if (len > _audiod_fct[func_id].ctrl_buf_sz) len = _audiod_fct[func_id].ctrl_buf_sz;
 
   // Copy into buffer
-  memcpy((void *)_audiod_fct[func_id].ctrl_buf, data, (size_t)len);
+  TU_VERIFY(0 == tu_memcpy_s(_audiod_fct[func_id].ctrl_buf, _audiod_fct[func_id].ctrl_buf_sz, data, (size_t)len));
 
   // Schedule transmit
   return tud_control_xfer(rhport, p_request, (void*)_audiod_fct[func_id].ctrl_buf, len);
@@ -2164,6 +2437,16 @@ static bool audiod_verify_ep_exists(uint8_t ep, uint8_t *func_id)
 // Currently, only AS interfaces with an EP (in or out) are supposed to be parsed for!
 static void audiod_parse_for_AS_params(audiod_function_t* audio, uint8_t const * p_desc, uint8_t const * p_desc_end, uint8_t const as_itf)
 {
+#if CFG_TUD_AUDIO_ENABLE_EP_IN && CFG_TUD_AUDIO_ENABLE_EP_OUT
+  if (as_itf != audio->ep_in_as_intf_num && as_itf != audio->ep_out_as_intf_num) return;           // Abort, this interface has no EP, this driver does not support this currently
+#endif
+#if CFG_TUD_AUDIO_ENABLE_EP_IN && !CFG_TUD_AUDIO_ENABLE_EP_OUT
+  if (as_itf != audio->ep_in_as_intf_num) return;
+#endif
+#if !CFG_TUD_AUDIO_ENABLE_EP_IN && CFG_TUD_AUDIO_ENABLE_EP_OUT
+  if (as_itf != audio->ep_out_as_intf_num) return;
+#endif
+
   p_desc = tu_desc_next(p_desc);    // Exclude standard AS interface descriptor of current alternate interface descriptor
 
   while (p_desc < p_desc_end)
@@ -2174,16 +2457,6 @@ static void audiod_parse_for_AS_params(audiod_function_t* audio, uint8_t const *
     // Look for a Class-Specific AS Interface Descriptor(4.9.2) to verify format type and format and also to get number of physical channels
     if (tu_desc_type(p_desc) == TUSB_DESC_CS_INTERFACE && tu_desc_subtype(p_desc) == AUDIO_CS_AS_INTERFACE_AS_GENERAL)
     {
-#if CFG_TUD_AUDIO_ENABLE_EP_IN && CFG_TUD_AUDIO_ENABLE_EP_OUT
-      if (as_itf != audio->ep_in_as_intf_num && as_itf != audio->ep_out_as_intf_num) break;           // Abort loop, this interface has no EP, this driver does not support this currently
-#endif
-#if CFG_TUD_AUDIO_ENABLE_EP_IN && !CFG_TUD_AUDIO_ENABLE_EP_OUT
-      if (as_itf != audio->ep_in_as_intf_num) break;
-#endif
-#if !CFG_TUD_AUDIO_ENABLE_EP_IN && CFG_TUD_AUDIO_ENABLE_EP_OUT
-      if (as_itf != audio->ep_out_as_intf_num) break;
-#endif
-
 #if CFG_TUD_AUDIO_ENABLE_EP_IN
       if (as_itf == audio->ep_in_as_intf_num)
       {
@@ -2255,7 +2528,7 @@ bool tud_audio_n_fb_set(uint8_t func_id, uint32_t feedback)
 #if CFG_TUD_AUDIO_ENABLE_FEEDBACK_FORMAT_CORRECTION
   if ( TUSB_SPEED_FULL == tud_speed_get() )
   {
-    uint8_t * fb = (uint8_t *) &_audiod_fct[func_id].fb_val;
+    uint8_t * fb = (uint8_t *) &_audiod_fct[func_id].feedback.value;
 
     // For FS format is 10.14
     *(fb++) = (feedback >> 2) & 0xFF;
@@ -2267,7 +2540,7 @@ bool tud_audio_n_fb_set(uint8_t func_id, uint32_t feedback)
 #else
   {
     // Send value as-is, caller will choose the appropriate format
-    _audiod_fct[func_id].fb_val = feedback;
+    _audiod_fct[func_id].feedback.value = feedback;
   }
 #endif
 
diff --git a/src/class/audio/audio_device.h b/src/class/audio/audio_device.h
index f406cf281..7c88b99fc 100644
--- a/src/class/audio/audio_device.h
+++ b/src/class/audio/audio_device.h
@@ -1,4 +1,4 @@
-/* 
+/*
  * The MIT License (MIT)
  *
  * Copyright (c) 2020 Ha Thach (tinyusb.org)
@@ -458,7 +458,14 @@ TU_ATTR_WEAK bool tud_audio_rx_done_post_read_cb(uint8_t rhport, uint16_t n_byte
 #endif
 
 #if CFG_TUD_AUDIO_ENABLE_EP_OUT && CFG_TUD_AUDIO_ENABLE_FEEDBACK_EP
-TU_ATTR_WEAK bool tud_audio_fb_done_cb(uint8_t rhport);
+TU_ATTR_WEAK void tud_audio_fb_done_cb(uint8_t func_id);
+
+
+// determined by the user itself and set by use of tud_audio_n_fb_set(). The feedback value may be determined e.g. from some fill status of some FIFO buffer. Advantage: No ISR interrupt is enabled, hence the CPU need not to handle an ISR every 1ms or 125us and thus less CPU load, disadvantage: typically a larger FIFO is needed to compensate for jitter (e.g. 8 frames), i.e. a larger delay is introduced.
+
+// Feedback value is calculated within the audio driver by use of SOF interrupt. The driver needs information about the master clock f_m from which the audio sample frequency f_s is derived, f_s itself, and the cycle count of f_m at time of the SOF interrupt (e.g. by use of a hardware counter) - see tud_audio_set_fb_params(). Advantage: Reduced jitter in the feedback value computation, hence, the receive FIFO can be smaller (e.g. 2 frames) and thus a smaller delay is possible, disadvantage: higher CPU load due to SOF ISR handling every frame i.e. 1ms or 125us. This option is a great starting point to try the SOF ISR option but depending on your hardware setup (performance of the CPU) it might not work. If so, figure out why and use the next option. (The most critical point is the reading of the cycle counter value of f_m. It is read from within the SOF ISR - see: audiod_sof() -, hence, the ISR must has a high priority such that no software dependent "random" delay i.e. jitter is introduced).
+
+// Feedback value is determined by the user by use of SOF interrupt. The user may use tud_audio_sof_isr() which is called every SOF (of course only invoked when an alternate interface other than zero was set). The number of frames used to determine the feedback value for the currently active alternate setting can be get by tud_audio_get_fb_n_frames(). The feedback value must be set by use of tud_audio_n_fb_set().
 
 // This function is used to provide data rate feedback from an asynchronous sink. Feedback value will be sent at FB endpoint interval till it's changed.
 //
@@ -466,11 +473,63 @@ TU_ATTR_WEAK bool tud_audio_fb_done_cb(uint8_t rhport);
 // the choice of format is left to the caller and feedback argument is sent as-is. If CFG_TUD_AUDIO_ENABLE_FEEDBACK_FORMAT_CORRECTION is set, then tinyusb
 // expects 16.16 format and handles the conversion to 10.14 on FS.
 //
-// Note that due to a bug in its USB Audio 2.0 driver, Windows currently requires 16.16 format for _all_ USB 2.0 devices. On Linux and macOS it seems the 
+// Note that due to a bug in its USB Audio 2.0 driver, Windows currently requires 16.16 format for _all_ USB 2.0 devices. On Linux and macOS it seems the
 // driver can work with either format. So a good compromise is to keep format correction disabled and stick to 16.16 format.
+
+// Feedback value can be determined from within the SOF ISR of the audio driver. This should reduce jitter. If the feature is used, the user can not set the feedback value.
+
+// Determine feedback value - The feedback method is described in 5.12.4.2 of the USB 2.0 spec
+// Boiled down, the feedback value Ff = n_samples / (micro)frame.
+// Since an accuracy of less than 1 Sample / second is desired, at least n_frames = ceil(2^K * f_s / f_m) frames need to be measured, where K = 10 for full speed and K = 13 for high speed, f_s is the sampling frequency e.g. 48 kHz and f_m is the cpu clock frequency e.g. 100 MHz (or any other master clock whose clock count is available and locked to f_s)
+// The update interval in the (4.10.2.1) Feedback Endpoint Descriptor must be less or equal to 2^(K - P), where P = min( ceil(log2(f_m / f_s)), K)
+// feedback = n_cycles / n_frames * f_s / f_m in 16.16 format, where n_cycles are the number of main clock cycles within fb_n_frames
+
 bool tud_audio_n_fb_set(uint8_t func_id, uint32_t feedback);
 static inline bool tud_audio_fb_set(uint32_t feedback);
+
+// Update feedback value with passed cycles since last time this update function is called.
+// Typically called within tud_audio_sof_isr(). Required tud_audio_feedback_params_cb() is implemented
+// This function will also call tud_audio_feedback_set()
+// return feedback value in 16.16 for reference (0 for error)
+uint32_t tud_audio_feedback_update(uint8_t func_id, uint32_t cycles);
+
+enum {
+  AUDIO_FEEDBACK_METHOD_DISABLED,
+  AUDIO_FEEDBACK_METHOD_FREQUENCY_FIXED,
+  AUDIO_FEEDBACK_METHOD_FREQUENCY_FLOAT,
+  AUDIO_FEEDBACK_METHOD_FREQUENCY_POWER_OF_2,
+
+  // impelemnt later
+  // AUDIO_FEEDBACK_METHOD_FIFO_COUNT
+};
+
+typedef struct {
+  uint8_t method;
+  uint32_t sample_freq;   //  sample frequency in Hz
+
+  union {
+    struct {
+      uint32_t mclk_freq; // Main clock frequency in Hz i.e. master clock to which sample clock is based on
+    }frequency;
+
+#if 0 // implement later
+    struct {
+      uint32_t threshold_bytes; // minimum number of bytes received to be considered as filled/ready
+    }fifo_count;
 #endif
+  };
+}audio_feedback_params_t;
+
+// Invoked when needed to set feedback parameters
+TU_ATTR_WEAK void tud_audio_feedback_params_cb(uint8_t func_id, uint8_t alt_itf, audio_feedback_params_t* feedback_param);
+
+// Callback in ISR context, invoked periodically according to feedback endpoint bInterval.
+// Could be used to compute and update feedback value, should be placed in RAM if possible
+// frame_number  : current SOF count
+// interval_shift: number of bit shift i.e log2(interval) from Feedback endpoint descriptor
+TU_ATTR_WEAK TU_ATTR_FAST_FUNC void tud_audio_feedback_interval_isr(uint8_t func_id, uint32_t frame_number, uint8_t interval_shift);
+
+#endif // CFG_TUD_AUDIO_ENABLE_EP_OUT && CFG_TUD_AUDIO_ENABLE_FEEDBACK_EP
 
 #if CFG_TUD_AUDIO_INT_CTR_EPSIZE_IN
 TU_ATTR_WEAK bool tud_audio_int_ctr_done_cb(uint8_t rhport, uint16_t n_bytes_copied);
@@ -612,10 +671,12 @@ static inline uint16_t tud_audio_int_ctr_write(uint8_t const* buffer, uint16_t l
 #endif
 
 #if CFG_TUD_AUDIO_ENABLE_EP_OUT && CFG_TUD_AUDIO_ENABLE_FEEDBACK_EP
+
 static inline bool tud_audio_fb_set(uint32_t feedback)
 {
   return tud_audio_n_fb_set(0, feedback);
 }
+
 #endif
 
 //--------------------------------------------------------------------+
@@ -626,6 +687,7 @@ void     audiod_reset          (uint8_t rhport);
 uint16_t audiod_open           (uint8_t rhport, tusb_desc_interface_t const * itf_desc, uint16_t max_len);
 bool     audiod_control_xfer_cb(uint8_t rhport, uint8_t stage, tusb_control_request_t const * request);
 bool     audiod_xfer_cb        (uint8_t rhport, uint8_t edpt_addr, xfer_result_t result, uint32_t xferred_bytes);
+void     audiod_sof_isr        (uint8_t rhport, uint32_t frame_count);
 
 #ifdef __cplusplus
 }
diff --git a/src/class/bth/bth_device.c b/src/class/bth/bth_device.c
index f40bfbd0d..f96bb3552 100755
--- a/src/class/bth/bth_device.c
+++ b/src/class/bth/bth_device.c
@@ -59,10 +59,12 @@ CFG_TUSB_MEM_SECTION btd_interface_t _btd_itf;
 
 static bool bt_tx_data(uint8_t ep, void *data, uint16_t len)
 {
+  uint8_t const rhport = 0;
+
   // skip if previous transfer not complete
-  TU_VERIFY(!usbd_edpt_busy(TUD_OPT_RHPORT, ep));
+  TU_VERIFY(!usbd_edpt_busy(rhport, ep));
 
-  TU_ASSERT(usbd_edpt_xfer(TUD_OPT_RHPORT, ep, data, len));
+  TU_ASSERT(usbd_edpt_xfer(rhport, ep, data, len));
 
   return true;
 }
diff --git a/src/class/bth/bth_device.h b/src/class/bth/bth_device.h
index 1b90d0915..921bd7a1a 100755
--- a/src/class/bth/bth_device.h
+++ b/src/class/bth/bth_device.h
@@ -1,4 +1,4 @@
-/* 
+/*
  * The MIT License (MIT)
  *
  * Copyright (c) 2020 Jerzy Kasenberg
diff --git a/src/class/cdc/cdc.h b/src/class/cdc/cdc.h
index e345139ea..4658e43af 100644
--- a/src/class/cdc/cdc.h
+++ b/src/class/cdc/cdc.h
@@ -41,16 +41,6 @@
 /** \defgroup ClassDriver_CDC_Common Common Definitions
  *  @{ */
 
-// TODO remove
-/// CDC Pipe ID, used to indicate which pipe the API is addressing to (Notification, Out, In)
-typedef enum
-{
-  CDC_PIPE_NOTIFICATION , ///< Notification pipe
-  CDC_PIPE_DATA_IN      , ///< Data in pipe
-  CDC_PIPE_DATA_OUT     , ///< Data out pipe
-  CDC_PIPE_ERROR        , ///< Invalid Pipe ID
-}cdc_pipeid_t;
-
 //--------------------------------------------------------------------+
 // CDC Communication Interface Class
 //--------------------------------------------------------------------+
@@ -192,8 +182,30 @@ typedef enum
   CDC_REQUEST_MDLM_SEMANTIC_MODEL                          = 0x60,
 }cdc_management_request_t;
 
+enum
+{
+  CDC_CONTROL_LINE_STATE_DTR = 0x01,
+  CDC_CONTROL_LINE_STATE_RTS = 0x02,
+};
+
+enum
+{
+  CDC_LINE_CONDING_STOP_BITS_1   = 0, // 1   bit
+  CDC_LINE_CONDING_STOP_BITS_1_5 = 1, // 1.5 bits
+  CDC_LINE_CONDING_STOP_BITS_2   = 2, // 2   bits
+};
+
+enum
+{
+  CDC_LINE_CODING_PARITY_NONE  = 0,
+  CDC_LINE_CODING_PARITY_ODD   = 1,
+  CDC_LINE_CODING_PARITY_EVEN  = 2,
+  CDC_LINE_CODING_PARITY_MARK  = 3,
+  CDC_LINE_CODING_PARITY_SPACE = 4,
+};
+
 //--------------------------------------------------------------------+
-// Management Elemenent Notification (Notification Endpoint)
+// Management Element Notification (Notification Endpoint)
 //--------------------------------------------------------------------+
 
 /// 6.3 Notification Codes
@@ -365,7 +377,9 @@ typedef struct TU_ATTR_PACKED
     uint32_t incoming_distinctive   : 1; ///< 0 : Reports only incoming ringing. 1 : Reports incoming distinctive ringing patterns.
     uint32_t dual_tone_multi_freq   : 1; ///< 0 : Cannot report dual tone multi-frequency (DTMF) digits input remotely over the telephone line. 1 : Can report DTMF digits input remotely over the telephone line.
     uint32_t line_state_change      : 1; ///< 0 : Does not support line state change notification. 1 : Does support line state change notification
-    uint32_t TU_RESERVED            : 26;
+    uint32_t TU_RESERVED0           : 2;
+    uint32_t TU_RESERVED1           : 16;
+    uint32_t TU_RESERVED2           : 8;
   } bmCapabilities;
 }cdc_desc_func_telephone_call_state_reporting_capabilities_t;
 
@@ -390,9 +404,10 @@ TU_VERIFY_STATIC(sizeof(cdc_line_coding_t) == 7, "size is not correct");
 
 typedef struct TU_ATTR_PACKED
 {
-  uint16_t dte_is_present : 1; ///< Indicates to DCE if DTE is presentor not. This signal corresponds to V.24 signal 108/2 and RS-232 signal DTR.
-  uint16_t half_duplex_carrier_control : 1;
-  uint16_t : 14;
+  uint16_t dtr : 1;
+  uint16_t rts : 1;
+  uint16_t : 6;
+  uint16_t : 8;
 } cdc_line_control_state_t;
 
 TU_VERIFY_STATIC(sizeof(cdc_line_control_state_t) == 2, "size is not correct");
diff --git a/src/class/cdc/cdc_device.c b/src/class/cdc/cdc_device.c
index 2b9b84e7a..a82ef1d62 100644
--- a/src/class/cdc/cdc_device.c
+++ b/src/class/cdc/cdc_device.c
@@ -1,4 +1,4 @@
-/* 
+/*
  * The MIT License (MIT)
  *
  * Copyright (c) 2019 Ha Thach (tinyusb.org)
@@ -62,10 +62,8 @@ typedef struct
   uint8_t rx_ff_buf[CFG_TUD_CDC_RX_BUFSIZE];
   uint8_t tx_ff_buf[CFG_TUD_CDC_TX_BUFSIZE];
 
-#if CFG_FIFO_MUTEX
-  osal_mutex_def_t rx_ff_mutex;
-  osal_mutex_def_t tx_ff_mutex;
-#endif
+  OSAL_MUTEX_DEF(rx_ff_mutex);
+  OSAL_MUTEX_DEF(tx_ff_mutex);
 
   // Endpoint Transfer buffer
   CFG_TUSB_MEM_ALIGN uint8_t epout_buf[CFG_TUD_CDC_EP_BUFSIZE];
@@ -78,11 +76,11 @@ typedef struct
 //--------------------------------------------------------------------+
 // INTERNAL OBJECT & FUNCTION DECLARATION
 //--------------------------------------------------------------------+
-CFG_TUSB_MEM_SECTION static cdcd_interface_t _cdcd_itf[CFG_TUD_CDC];
+CFG_TUSB_MEM_SECTION tu_static cdcd_interface_t _cdcd_itf[CFG_TUD_CDC];
 
 static bool _prep_out_transaction (cdcd_interface_t* p_cdc)
 {
-  uint8_t const rhport = TUD_OPT_RHPORT;
+  uint8_t const rhport = 0;
   uint16_t available = tu_fifo_remaining(&p_cdc->rx_ff);
 
   // Prepare for incoming data but only allow what we can store in the ring buffer.
@@ -145,7 +143,7 @@ uint32_t tud_cdc_n_available(uint8_t itf)
 uint32_t tud_cdc_n_read(uint8_t itf, void* buffer, uint32_t bufsize)
 {
   cdcd_interface_t* p_cdc = &_cdcd_itf[itf];
-  uint32_t num_read = tu_fifo_read_n(&p_cdc->rx_ff, buffer, bufsize);
+  uint32_t num_read = tu_fifo_read_n(&p_cdc->rx_ff, buffer, (uint16_t) bufsize);
   _prep_out_transaction(p_cdc);
   return num_read;
 }
@@ -168,10 +166,11 @@ void tud_cdc_n_read_flush (uint8_t itf)
 uint32_t tud_cdc_n_write(uint8_t itf, void const* buffer, uint32_t bufsize)
 {
   cdcd_interface_t* p_cdc = &_cdcd_itf[itf];
-  uint16_t ret = tu_fifo_write_n(&p_cdc->tx_ff, buffer, bufsize);
+  uint16_t ret = tu_fifo_write_n(&p_cdc->tx_ff, buffer, (uint16_t) bufsize);
 
   // flush if queue more than packet size
-  if ( tu_fifo_count(&p_cdc->tx_ff) >= BULK_PACKET_SIZE )
+  // may need to suppress -Wunreachable-code since most of the time CFG_TUD_CDC_TX_BUFSIZE < BULK_PACKET_SIZE
+  if ( (tu_fifo_count(&p_cdc->tx_ff) >= BULK_PACKET_SIZE) || ((CFG_TUD_CDC_TX_BUFSIZE < BULK_PACKET_SIZE) && tu_fifo_full(&p_cdc->tx_ff)) )
   {
     tud_cdc_n_write_flush(itf);
   }
@@ -189,7 +188,7 @@ uint32_t tud_cdc_n_write_flush (uint8_t itf)
   // No data to send
   if ( !tu_fifo_count(&p_cdc->tx_ff) ) return 0;
 
-  uint8_t const rhport = TUD_OPT_RHPORT;
+  uint8_t const rhport = 0;
 
   // Claim the endpoint
   TU_VERIFY( usbd_edpt_claim(rhport, p_cdc->ep_in), 0 );
@@ -247,10 +246,8 @@ void cdcd_init(void)
     // In this way, the most current data is prioritized.
     tu_fifo_config(&p_cdc->tx_ff, p_cdc->tx_ff_buf, TU_ARRAY_SIZE(p_cdc->tx_ff_buf), 1, true);
 
-#if CFG_FIFO_MUTEX
     tu_fifo_config_mutex(&p_cdc->rx_ff, NULL, osal_mutex_create(&p_cdc->rx_ff_mutex));
     tu_fifo_config_mutex(&p_cdc->tx_ff, osal_mutex_create(&p_cdc->tx_ff_mutex), NULL);
-#endif
   }
 }
 
@@ -389,7 +386,7 @@ bool cdcd_control_xfer_cb(uint8_t rhport, uint8_t stage, tusb_control_request_t
         bool const rts = tu_bit_test(request->wValue, 1);
 
         p_cdc->line_state = (uint8_t) request->wValue;
-        
+
         // Disable fifo overwriting if DTR bit is set
         tu_fifo_set_overwritable(&p_cdc->tx_ff, !dtr);
 
@@ -435,8 +432,8 @@ bool cdcd_xfer_cb(uint8_t rhport, uint8_t ep_addr, xfer_result_t result, uint32_
   // Received new data
   if ( ep_addr == p_cdc->ep_out )
   {
-    tu_fifo_write_n(&p_cdc->rx_ff, &p_cdc->epout_buf, xferred_bytes);
-    
+    tu_fifo_write_n(&p_cdc->rx_ff, p_cdc->epout_buf, (uint16_t) xferred_bytes);
+
     // Check for wanted char and invoke callback if needed
     if ( tud_cdc_rx_wanted_cb && (((signed char) p_cdc->wanted_char) != -1) )
     {
@@ -448,14 +445,14 @@ bool cdcd_xfer_cb(uint8_t rhport, uint8_t ep_addr, xfer_result_t result, uint32_
         }
       }
     }
-    
+
     // invoke receive callback (if there is still data)
     if (tud_cdc_rx_cb && !tu_fifo_empty(&p_cdc->rx_ff) ) tud_cdc_rx_cb(itf);
-    
+
     // prepare for OUT transaction
     _prep_out_transaction(p_cdc);
   }
-  
+
   // Data sent to host, we continue to fetch from tx fifo to send.
   // Note: This will cause incorrect baudrate set in line coding.
   //       Though maybe the baudrate is not really important !!!
diff --git a/src/class/cdc/cdc_device.h b/src/class/cdc/cdc_device.h
index fbc7162a3..a6e07aa5c 100644
--- a/src/class/cdc/cdc_device.h
+++ b/src/class/cdc/cdc_device.h
@@ -1,4 +1,4 @@
-/* 
+/*
  * The MIT License (MIT)
  *
  * Copyright (c) 2019 Ha Thach (tinyusb.org)
@@ -27,7 +27,6 @@
 #ifndef _TUSB_CDC_DEVICE_H_
 #define _TUSB_CDC_DEVICE_H_
 
-#include "common/tusb_common.h"
 #include "cdc.h"
 
 //--------------------------------------------------------------------+
@@ -81,7 +80,7 @@ int32_t  tud_cdc_n_read_char       (uint8_t itf);
 // Clear the received FIFO
 void     tud_cdc_n_read_flush      (uint8_t itf);
 
-// Get a byte from FIFO at the specified position without removing it
+// Get a byte from FIFO without removing it
 bool     tud_cdc_n_peek            (uint8_t itf, uint8_t* ui8);
 
 // Write bytes to TX FIFO, data may remain in the FIFO for a while
@@ -135,7 +134,7 @@ TU_ATTR_WEAK void tud_cdc_rx_cb(uint8_t itf);
 // Invoked when received `wanted_char`
 TU_ATTR_WEAK void tud_cdc_rx_wanted_cb(uint8_t itf, char wanted_char);
 
-// Invoked when space becomes available in TX buffer
+// Invoked when a TX is complete and therefore space becomes available in TX buffer
 TU_ATTR_WEAK void tud_cdc_tx_complete_cb(uint8_t itf);
 
 // Invoked when line state DTR & RTS are changed via SET_CONTROL_LINE_STATE
diff --git a/src/class/cdc/cdc_host.c b/src/class/cdc/cdc_host.c
index 044085e81..c0cc41adf 100644
--- a/src/class/cdc/cdc_host.c
+++ b/src/class/cdc/cdc_host.c
@@ -1,4 +1,4 @@
-/* 
+/*
  * The MIT License (MIT)
  *
  * Copyright (c) 2019 Ha Thach (tinyusb.org)
@@ -33,96 +33,270 @@
 
 #include "cdc_host.h"
 
+
+// Debug level, TUSB_CFG_DEBUG must be at least this level for debug message
+#define CDCH_DEBUG   2
+
+#define TU_LOG_CDCH(...)   TU_LOG(CDCH_DEBUG, __VA_ARGS__)
+
 //--------------------------------------------------------------------+
 // MACRO CONSTANT TYPEDEF
 //--------------------------------------------------------------------+
+
 typedef struct {
-  uint8_t itf_num;
-  uint8_t itf_protocol;
+  uint8_t daddr;
+  uint8_t bInterfaceNumber;
+  uint8_t bInterfaceSubClass;
+  uint8_t bInterfaceProtocol;
 
+  cdc_acm_capability_t acm_capability;
   uint8_t ep_notif;
-  uint8_t ep_in;
-  uint8_t ep_out;
 
-  cdc_acm_capability_t acm_capability;
+  cdc_line_coding_t line_coding;  // Baudrate, stop bits, parity, data width
+  uint8_t line_state;             // DTR (bit0), RTS (bit1)
 
-} cdch_data_t;
+  tuh_xfer_cb_t user_control_cb;
+
+  struct {
+    tu_edpt_stream_t tx;
+    tu_edpt_stream_t rx;
+
+    uint8_t tx_ff_buf[CFG_TUH_CDC_TX_BUFSIZE];
+    CFG_TUH_MEM_ALIGN uint8_t tx_ep_buf[CFG_TUH_CDC_TX_EPSIZE];
+
+    uint8_t rx_ff_buf[CFG_TUH_CDC_TX_BUFSIZE];
+    CFG_TUH_MEM_ALIGN uint8_t rx_ep_buf[CFG_TUH_CDC_TX_EPSIZE];
+  } stream;
+
+} cdch_interface_t;
 
 //--------------------------------------------------------------------+
 // INTERNAL OBJECT & FUNCTION DECLARATION
 //--------------------------------------------------------------------+
-static cdch_data_t cdch_data[CFG_TUH_DEVICE_MAX];
 
-static inline cdch_data_t* get_itf(uint8_t dev_addr)
+CFG_TUH_MEM_SECTION
+static cdch_interface_t cdch_data[CFG_TUH_CDC];
+
+static inline cdch_interface_t* get_itf(uint8_t idx)
 {
-  return &cdch_data[dev_addr-1];
+  TU_ASSERT(idx < CFG_TUH_CDC, NULL);
+  cdch_interface_t* p_cdc = &cdch_data[idx];
+
+  return (p_cdc->daddr != 0) ? p_cdc : NULL;
 }
 
-bool tuh_cdc_mounted(uint8_t dev_addr)
+static inline uint8_t get_idx_by_ep_addr(uint8_t daddr, uint8_t ep_addr)
 {
-  cdch_data_t* cdc = get_itf(dev_addr);
-  return cdc->ep_in && cdc->ep_out;
+  for(uint8_t i=0; i<CFG_TUH_CDC; i++)
+  {
+    cdch_interface_t* p_cdc = &cdch_data[i];
+    if ( (p_cdc->daddr == daddr) &&
+         (ep_addr == p_cdc->ep_notif || ep_addr == p_cdc->stream.rx.ep_addr || ep_addr == p_cdc->stream.tx.ep_addr))
+    {
+      return i;
+    }
+  }
+
+  return TUSB_INDEX_INVALID_8;
 }
 
-bool tuh_cdc_is_busy(uint8_t dev_addr, cdc_pipeid_t pipeid)
+
+static cdch_interface_t* find_new_itf(void)
 {
-  if ( !tuh_cdc_mounted(dev_addr) ) return false;
+  for(uint8_t i=0; i<CFG_TUH_CDC; i++)
+  {
+    if (cdch_data[i].daddr == 0) return &cdch_data[i];
+  }
 
-  cdch_data_t const * p_cdc = get_itf(dev_addr);
+  return NULL;
+}
 
-  switch (pipeid)
+//--------------------------------------------------------------------+
+// APPLICATION API
+//--------------------------------------------------------------------+
+
+uint8_t tuh_cdc_itf_get_index(uint8_t daddr, uint8_t itf_num)
+{
+  for(uint8_t i=0; i<CFG_TUH_CDC; i++)
   {
-    case CDC_PIPE_NOTIFICATION:
-      return usbh_edpt_busy(dev_addr, p_cdc->ep_notif );
+    const cdch_interface_t* p_cdc = &cdch_data[i];
 
-    case CDC_PIPE_DATA_IN:
-      return usbh_edpt_busy(dev_addr, p_cdc->ep_in );
+    if (p_cdc->daddr == daddr && p_cdc->bInterfaceNumber == itf_num) return i;
+  }
 
-    case CDC_PIPE_DATA_OUT:
-      return usbh_edpt_busy(dev_addr, p_cdc->ep_out );
+  return TUSB_INDEX_INVALID_8;
+}
 
-    default:
-      return false;
-  }
+bool tuh_cdc_itf_get_info(uint8_t idx, tuh_itf_info_t* info)
+{
+  cdch_interface_t* p_cdc = get_itf(idx);
+  TU_VERIFY(p_cdc && info);
+
+  info->daddr = p_cdc->daddr;
+
+  // re-construct descriptor
+  tusb_desc_interface_t* desc = &info->desc;
+  desc->bLength            = sizeof(tusb_desc_interface_t);
+  desc->bDescriptorType    = TUSB_DESC_INTERFACE;
+
+  desc->bInterfaceNumber   = p_cdc->bInterfaceNumber;
+  desc->bAlternateSetting  = 0;
+  desc->bNumEndpoints      = 2u + (p_cdc->ep_notif ? 1u : 0u);
+  desc->bInterfaceClass    = TUSB_CLASS_CDC;
+  desc->bInterfaceSubClass = p_cdc->bInterfaceSubClass;
+  desc->bInterfaceProtocol = p_cdc->bInterfaceProtocol;
+  desc->iInterface         = 0; // not used yet
+
+  return true;
+}
+
+bool tuh_cdc_mounted(uint8_t idx)
+{
+  cdch_interface_t* p_cdc = get_itf(idx);
+  return p_cdc != NULL;
+}
+
+bool tuh_cdc_get_dtr(uint8_t idx)
+{
+  cdch_interface_t* p_cdc = get_itf(idx);
+  TU_VERIFY(p_cdc);
+
+  return (p_cdc->line_state & CDC_CONTROL_LINE_STATE_DTR) ? true : false;
+}
+
+bool tuh_cdc_get_rts(uint8_t idx)
+{
+  cdch_interface_t* p_cdc = get_itf(idx);
+  TU_VERIFY(p_cdc);
+
+  return (p_cdc->line_state & CDC_CONTROL_LINE_STATE_RTS) ? true : false;
+}
+
+bool tuh_cdc_get_local_line_coding(uint8_t idx, cdc_line_coding_t* line_coding)
+{
+  cdch_interface_t* p_cdc = get_itf(idx);
+  TU_VERIFY(p_cdc);
+
+  *line_coding = p_cdc->line_coding;
+
+  return true;
 }
 
 //--------------------------------------------------------------------+
-// APPLICATION API (parameter validation needed)
+// Write
 //--------------------------------------------------------------------+
-bool tuh_cdc_serial_is_mounted(uint8_t dev_addr)
+
+uint32_t tuh_cdc_write(uint8_t idx, void const* buffer, uint32_t bufsize)
+{
+  cdch_interface_t* p_cdc = get_itf(idx);
+  TU_VERIFY(p_cdc);
+
+  return tu_edpt_stream_write(&p_cdc->stream.tx, buffer, bufsize);
+}
+
+uint32_t tuh_cdc_write_flush(uint8_t idx)
+{
+  cdch_interface_t* p_cdc = get_itf(idx);
+  TU_VERIFY(p_cdc);
+
+  return tu_edpt_stream_write_xfer(&p_cdc->stream.tx);
+}
+
+bool tuh_cdc_write_clear(uint8_t idx)
+{
+  cdch_interface_t* p_cdc = get_itf(idx);
+  TU_VERIFY(p_cdc);
+
+  return tu_edpt_stream_clear(&p_cdc->stream.tx);
+}
+
+uint32_t tuh_cdc_write_available(uint8_t idx)
 {
-  // TODO consider all AT Command as serial candidate
-  return tuh_cdc_mounted(dev_addr)                                         &&
-      (cdch_data[dev_addr-1].itf_protocol <= CDC_COMM_PROTOCOL_ATCOMMAND_CDMA);
+  cdch_interface_t* p_cdc = get_itf(idx);
+  TU_VERIFY(p_cdc);
+
+  return tu_edpt_stream_write_available(&p_cdc->stream.tx);
 }
 
-bool tuh_cdc_send(uint8_t dev_addr, void const * p_data, uint32_t length, bool is_notify)
+//--------------------------------------------------------------------+
+// Read
+//--------------------------------------------------------------------+
+
+uint32_t tuh_cdc_read (uint8_t idx, void* buffer, uint32_t bufsize)
 {
-  (void) is_notify;
-  TU_VERIFY( tuh_cdc_mounted(dev_addr) );
-  TU_VERIFY( p_data != NULL && length);
+  cdch_interface_t* p_cdc = get_itf(idx);
+  TU_VERIFY(p_cdc);
 
-  uint8_t const ep_out = cdch_data[dev_addr-1].ep_out;
-  if ( usbh_edpt_busy(dev_addr, ep_out) ) return false;
+  return tu_edpt_stream_read(&p_cdc->stream.rx, buffer, bufsize);
+}
 
-  return usbh_edpt_xfer(dev_addr, ep_out, (void*)(uintptr_t) p_data, length);
+uint32_t tuh_cdc_read_available(uint8_t idx)
+{
+  cdch_interface_t* p_cdc = get_itf(idx);
+  TU_VERIFY(p_cdc);
+
+  return tu_edpt_stream_read_available(&p_cdc->stream.rx);
 }
 
-bool tuh_cdc_receive(uint8_t dev_addr, void * p_buffer, uint32_t length, bool is_notify)
+bool tuh_cdc_peek(uint8_t idx, uint8_t* ch)
 {
-  (void) is_notify;
-  TU_VERIFY( tuh_cdc_mounted(dev_addr) );
-  TU_VERIFY( p_buffer != NULL && length );
+  cdch_interface_t* p_cdc = get_itf(idx);
+  TU_VERIFY(p_cdc);
 
-  uint8_t const ep_in = cdch_data[dev_addr-1].ep_in;
-  if ( usbh_edpt_busy(dev_addr, ep_in) ) return false;
+  return tu_edpt_stream_peek(&p_cdc->stream.rx, ch);
+}
 
-  return usbh_edpt_xfer(dev_addr, ep_in, p_buffer, length);
+bool tuh_cdc_read_clear (uint8_t idx)
+{
+  cdch_interface_t* p_cdc = get_itf(idx);
+  TU_VERIFY(p_cdc);
+
+  bool ret = tu_edpt_stream_clear(&p_cdc->stream.rx);
+  tu_edpt_stream_read_xfer(&p_cdc->stream.rx);
+  return ret;
 }
 
-bool tuh_cdc_set_control_line_state(uint8_t dev_addr, bool dtr, bool rts, tuh_xfer_cb_t complete_cb)
+//--------------------------------------------------------------------+
+// Control Endpoint API
+//--------------------------------------------------------------------+
+
+// internal control complete to update state such as line state, encoding
+static void cdch_internal_control_complete(tuh_xfer_t* xfer)
 {
-  cdch_data_t const * p_cdc = get_itf(dev_addr);
+  uint8_t const itf_num = (uint8_t) tu_le16toh(xfer->setup->wIndex);
+  uint8_t idx = tuh_cdc_itf_get_index(xfer->daddr, itf_num);
+  cdch_interface_t* p_cdc = get_itf(idx);
+  TU_ASSERT(p_cdc, );
+
+  if (xfer->result == XFER_RESULT_SUCCESS)
+  {
+    switch(xfer->setup->bRequest)
+    {
+      case CDC_REQUEST_SET_CONTROL_LINE_STATE:
+        p_cdc->line_state = (uint8_t) tu_le16toh(xfer->setup->wValue);
+      break;
+
+      case CDC_REQUEST_SET_LINE_CODING:
+      {
+        uint16_t const len = tu_min16(sizeof(cdc_line_coding_t), tu_le16toh(xfer->setup->wLength));
+        memcpy(&p_cdc->line_coding, xfer->buffer, len);
+      }
+      break;
+
+      default: break;
+    }
+  }
+
+  xfer->complete_cb = p_cdc->user_control_cb;
+  xfer->complete_cb(xfer);
+}
+
+bool tuh_cdc_set_control_line_state(uint8_t idx, uint16_t line_state, tuh_xfer_cb_t complete_cb, uintptr_t user_data)
+{
+  cdch_interface_t* p_cdc = get_itf(idx);
+  TU_VERIFY(p_cdc && p_cdc->acm_capability.support_line_request);
+
+  TU_LOG_CDCH("CDC Set Control Line State\r\n");
 
   tusb_control_request_t const request =
   {
@@ -133,36 +307,156 @@ bool tuh_cdc_set_control_line_state(uint8_t dev_addr, bool dtr, bool rts, tuh_xf
       .direction = TUSB_DIR_OUT
     },
     .bRequest = CDC_REQUEST_SET_CONTROL_LINE_STATE,
-    .wValue   = (rts ? 2 : 0) | (dtr ? 1 : 0),
-    .wIndex   = p_cdc->itf_num,
+    .wValue   = tu_htole16(line_state),
+    .wIndex   = tu_htole16((uint16_t) p_cdc->bInterfaceNumber),
     .wLength  = 0
   };
 
+  p_cdc->user_control_cb = complete_cb;
   tuh_xfer_t xfer =
   {
-    .daddr       = dev_addr,
+    .daddr       = p_cdc->daddr,
     .ep_addr     = 0,
     .setup       = &request,
     .buffer      = NULL,
-    .complete_cb = complete_cb,
-    .user_data    = 0
+    .complete_cb = cdch_internal_control_complete,
+    .user_data   = user_data
+  };
+
+  TU_ASSERT(tuh_control_xfer(&xfer));
+  return true;
+}
+
+bool tuh_cdc_set_line_coding(uint8_t idx, cdc_line_coding_t const* line_coding, tuh_xfer_cb_t complete_cb, uintptr_t user_data)
+{
+  cdch_interface_t* p_cdc = get_itf(idx);
+  TU_VERIFY(p_cdc && p_cdc->acm_capability.support_line_request);
+
+  TU_LOG_CDCH("CDC Set Line Conding\r\n");
+
+  tusb_control_request_t const request =
+  {
+    .bmRequestType_bit =
+    {
+      .recipient = TUSB_REQ_RCPT_INTERFACE,
+      .type      = TUSB_REQ_TYPE_CLASS,
+      .direction = TUSB_DIR_OUT
+    },
+    .bRequest = CDC_REQUEST_SET_LINE_CODING,
+    .wValue   = 0,
+    .wIndex   = tu_htole16(p_cdc->bInterfaceNumber),
+    .wLength  = tu_htole16(sizeof(cdc_line_coding_t))
   };
 
-  return tuh_control_xfer(&xfer);
+  // use usbh enum buf to hold line coding since user line_coding variable may not live long enough
+  // for the transfer to complete
+  uint8_t* enum_buf = usbh_get_enum_buf();
+  memcpy(enum_buf, line_coding, sizeof(cdc_line_coding_t));
+
+  p_cdc->user_control_cb = complete_cb;
+  tuh_xfer_t xfer =
+  {
+    .daddr       = p_cdc->daddr,
+    .ep_addr     = 0,
+    .setup       = &request,
+    .buffer      = enum_buf,
+    .complete_cb = cdch_internal_control_complete,
+    .user_data   = user_data
+  };
+
+  TU_ASSERT(tuh_control_xfer(&xfer));
+  return true;
 }
 
 //--------------------------------------------------------------------+
-// USBH-CLASS DRIVER API
+// CLASS-USBH API
 //--------------------------------------------------------------------+
+
 void cdch_init(void)
 {
   tu_memclr(cdch_data, sizeof(cdch_data));
+
+  for(size_t i=0; i<CFG_TUH_CDC; i++)
+  {
+    cdch_interface_t* p_cdc = &cdch_data[i];
+
+    tu_edpt_stream_init(&p_cdc->stream.tx, true, true, false,
+                          p_cdc->stream.tx_ff_buf, CFG_TUH_CDC_TX_BUFSIZE,
+                          p_cdc->stream.tx_ep_buf, CFG_TUH_CDC_TX_EPSIZE);
+
+    tu_edpt_stream_init(&p_cdc->stream.rx, true, false, false,
+                          p_cdc->stream.rx_ff_buf, CFG_TUH_CDC_RX_BUFSIZE,
+                          p_cdc->stream.rx_ep_buf, CFG_TUH_CDC_RX_EPSIZE);
+  }
+}
+
+void cdch_close(uint8_t daddr)
+{
+  for(uint8_t idx=0; idx<CFG_TUH_CDC; idx++)
+  {
+    cdch_interface_t* p_cdc = &cdch_data[idx];
+    if (p_cdc->daddr == daddr)
+    {
+      // Invoke application callback
+      if (tuh_cdc_umount_cb) tuh_cdc_umount_cb(idx);
+
+      //tu_memclr(p_cdc, sizeof(cdch_interface_t));
+      p_cdc->daddr = 0;
+      p_cdc->bInterfaceNumber = 0;
+      tu_edpt_stream_close(&p_cdc->stream.tx);
+      tu_edpt_stream_close(&p_cdc->stream.rx);
+    }
+  }
 }
 
-bool cdch_open(uint8_t rhport, uint8_t dev_addr, tusb_desc_interface_t const *itf_desc, uint16_t max_len)
+bool cdch_xfer_cb(uint8_t daddr, uint8_t ep_addr, xfer_result_t event, uint32_t xferred_bytes)
+{
+  // TODO handle stall response, retry failed transfer ...
+  TU_ASSERT(event == XFER_RESULT_SUCCESS);
+
+  uint8_t const idx = get_idx_by_ep_addr(daddr, ep_addr);
+  cdch_interface_t * p_cdc = get_itf(idx);
+  TU_ASSERT(p_cdc);
+
+  if ( ep_addr == p_cdc->stream.tx.ep_addr )
+  {
+    // invoke tx complete callback to possibly refill tx fifo
+    if (tuh_cdc_tx_complete_cb) tuh_cdc_tx_complete_cb(idx);
+
+    if ( 0 == tu_edpt_stream_write_xfer(&p_cdc->stream.tx) )
+    {
+      // If there is no data left, a ZLP should be sent if:
+      // - xferred_bytes is multiple of EP Packet size and not zero
+      tu_edpt_stream_write_zlp_if_needed(&p_cdc->stream.tx, xferred_bytes);
+    }
+  }
+  else if ( ep_addr == p_cdc->stream.rx.ep_addr )
+  {
+    tu_edpt_stream_read_xfer_complete(&p_cdc->stream.rx, xferred_bytes);
+
+    // invoke receive callback
+    if (tuh_cdc_rx_cb)  tuh_cdc_rx_cb(idx);
+
+    // prepare for next transfer if needed
+    tu_edpt_stream_read_xfer(&p_cdc->stream.rx);
+  }else if ( ep_addr == p_cdc->ep_notif )
+  {
+    // TODO handle notification endpoint
+  }else
+  {
+    TU_ASSERT(false);
+  }
+
+  return true;
+}
+
+//--------------------------------------------------------------------+
+// Enumeration
+//--------------------------------------------------------------------+
+
+bool cdch_open(uint8_t rhport, uint8_t daddr, tusb_desc_interface_t const *itf_desc, uint16_t max_len)
 {
   (void) rhport;
-  (void) max_len;
 
   // Only support ACM subclass
   // Protocol 0xFF can be RNDIS device for windows XP
@@ -170,17 +464,22 @@ bool cdch_open(uint8_t rhport, uint8_t dev_addr, tusb_desc_interface_t const *it
              CDC_COMM_SUBCLASS_ABSTRACT_CONTROL_MODEL == itf_desc->bInterfaceSubClass &&
              0xFF                                     != itf_desc->bInterfaceProtocol);
 
-  cdch_data_t * p_cdc = get_itf(dev_addr);
+  uint8_t const * p_desc_end = ((uint8_t const*) itf_desc) + max_len;
+
+  cdch_interface_t * p_cdc = find_new_itf();
+  TU_VERIFY(p_cdc);
 
-  p_cdc->itf_num      = itf_desc->bInterfaceNumber;
-  p_cdc->itf_protocol = itf_desc->bInterfaceProtocol;
+  p_cdc->daddr              = daddr;
+  p_cdc->bInterfaceNumber   = itf_desc->bInterfaceNumber;
+  p_cdc->bInterfaceSubClass = itf_desc->bInterfaceSubClass;
+  p_cdc->bInterfaceProtocol = itf_desc->bInterfaceProtocol;
+  p_cdc->line_state         = 0;
 
-  //------------- Communication Interface -------------//
-  uint16_t drv_len = tu_desc_len(itf_desc);
+  //------------- Control Interface -------------//
   uint8_t const * p_desc = tu_desc_next(itf_desc);
 
   // Communication Functional Descriptors
-  while( TUSB_DESC_CS_INTERFACE == tu_desc_type(p_desc) && drv_len <= max_len )
+  while( (p_desc < p_desc_end) && (TUSB_DESC_CS_INTERFACE == tu_desc_type(p_desc)) )
   {
     if ( CDC_FUNC_DESC_ABSTRACT_CONTROL_MANAGEMENT == cdc_functional_desc_typeof(p_desc) )
     {
@@ -188,19 +487,18 @@ bool cdch_open(uint8_t rhport, uint8_t dev_addr, tusb_desc_interface_t const *it
       p_cdc->acm_capability = ((cdc_desc_func_acm_t const *) p_desc)->bmCapabilities;
     }
 
-    drv_len += tu_desc_len(p_desc);
     p_desc = tu_desc_next(p_desc);
   }
 
-  if ( TUSB_DESC_ENDPOINT == tu_desc_type(p_desc) )
+  // Open notification endpoint of control interface if any
+  if (itf_desc->bNumEndpoints == 1)
   {
-    // notification endpoint
+    TU_ASSERT(TUSB_DESC_ENDPOINT == tu_desc_type(p_desc));
     tusb_desc_endpoint_t const * desc_ep = (tusb_desc_endpoint_t const *) p_desc;
 
-    TU_ASSERT( tuh_edpt_open(dev_addr, desc_ep) );
+    TU_ASSERT( tuh_edpt_open(daddr, desc_ep) );
     p_cdc->ep_notif = desc_ep->bEndpointAddress;
 
-    drv_len += tu_desc_len(p_desc);
     p_desc = tu_desc_next(p_desc);
   }
 
@@ -209,52 +507,100 @@ bool cdch_open(uint8_t rhport, uint8_t dev_addr, tusb_desc_interface_t const *it
        (TUSB_CLASS_CDC_DATA == ((tusb_desc_interface_t const *) p_desc)->bInterfaceClass) )
   {
     // next to endpoint descriptor
-    drv_len += tu_desc_len(p_desc);
     p_desc = tu_desc_next(p_desc);
 
     // data endpoints expected to be in pairs
     for(uint32_t i=0; i<2; i++)
     {
       tusb_desc_endpoint_t const *desc_ep = (tusb_desc_endpoint_t const *) p_desc;
-      TU_ASSERT(TUSB_DESC_ENDPOINT == desc_ep->bDescriptorType && TUSB_XFER_BULK == desc_ep->bmAttributes.xfer);
+      TU_ASSERT(TUSB_DESC_ENDPOINT == desc_ep->bDescriptorType &&
+                TUSB_XFER_BULK     == desc_ep->bmAttributes.xfer);
 
-      TU_ASSERT(tuh_edpt_open(dev_addr, desc_ep));
+      TU_ASSERT(tuh_edpt_open(daddr, desc_ep));
 
       if ( tu_edpt_dir(desc_ep->bEndpointAddress) == TUSB_DIR_IN )
       {
-        p_cdc->ep_in = desc_ep->bEndpointAddress;
+        tu_edpt_stream_open(&p_cdc->stream.rx, daddr, desc_ep);
       }else
       {
-        p_cdc->ep_out = desc_ep->bEndpointAddress;
+        tu_edpt_stream_open(&p_cdc->stream.tx, daddr, desc_ep);
       }
 
-      drv_len += tu_desc_len(p_desc);
-      p_desc = tu_desc_next( p_desc );
+      p_desc = tu_desc_next(p_desc);
     }
   }
 
   return true;
 }
 
-bool cdch_set_config(uint8_t dev_addr, uint8_t itf_num)
+enum
 {
-  (void) dev_addr; (void) itf_num;
-  return true;
-}
+  CONFIG_SET_CONTROL_LINE_STATE,
+  CONFIG_SET_LINE_CODING,
+  CONFIG_COMPLETE
+};
 
-bool cdch_xfer_cb(uint8_t dev_addr, uint8_t ep_addr, xfer_result_t event, uint32_t xferred_bytes)
+static void process_cdc_config(tuh_xfer_t* xfer)
 {
-  (void) ep_addr;
-  tuh_cdc_xfer_isr( dev_addr, event, 0, xferred_bytes );
-  return true;
+  uintptr_t const state = xfer->user_data;
+  uint8_t const itf_num = (uint8_t) tu_le16toh(xfer->setup->wIndex);
+  uint8_t const idx = tuh_cdc_itf_get_index(xfer->daddr, itf_num);
+  cdch_interface_t * p_cdc = get_itf(idx);
+  TU_ASSERT(p_cdc, );
+
+  switch(state)
+  {
+    case CONFIG_SET_CONTROL_LINE_STATE:
+      #if CFG_TUH_CDC_LINE_CONTROL_ON_ENUM
+      if (p_cdc->acm_capability.support_line_request)
+      {
+        TU_ASSERT( tuh_cdc_set_control_line_state(idx, CFG_TUH_CDC_LINE_CONTROL_ON_ENUM, process_cdc_config, CONFIG_SET_LINE_CODING), );
+        break;
+      }
+      #endif
+      TU_ATTR_FALLTHROUGH;
+
+    case CONFIG_SET_LINE_CODING:
+      #ifdef CFG_TUH_CDC_LINE_CODING_ON_ENUM
+      if (p_cdc->acm_capability.support_line_request)
+      {
+        cdc_line_coding_t line_coding = CFG_TUH_CDC_LINE_CODING_ON_ENUM;
+        TU_ASSERT( tuh_cdc_set_line_coding(idx, &line_coding, process_cdc_config, CONFIG_COMPLETE), );
+        break;
+      }
+      #endif
+      TU_ATTR_FALLTHROUGH;
+
+    case CONFIG_COMPLETE:
+      if (tuh_cdc_mount_cb) tuh_cdc_mount_cb(idx);
+
+      // Prepare for incoming data
+      tu_edpt_stream_read_xfer(&p_cdc->stream.rx);
+
+      // notify usbh that driver enumeration is complete
+      // itf_num+1 to account for data interface as well
+      usbh_driver_set_config_complete(xfer->daddr, itf_num+1);
+    break;
+
+    default: break;
+  }
 }
 
-void cdch_close(uint8_t dev_addr)
+bool cdch_set_config(uint8_t daddr, uint8_t itf_num)
 {
-  TU_VERIFY(dev_addr <= CFG_TUH_DEVICE_MAX, );
+  // fake transfer to kick-off process
+  tusb_control_request_t request;
+  request.wIndex = tu_htole16((uint16_t) itf_num);
+
+  tuh_xfer_t xfer;
+  xfer.daddr     = daddr;
+  xfer.result    = XFER_RESULT_SUCCESS;
+  xfer.setup     = &request;
+  xfer.user_data = CONFIG_SET_CONTROL_LINE_STATE;
 
-  cdch_data_t * p_cdc = get_itf(dev_addr);
-  tu_memclr(p_cdc, sizeof(cdch_data_t));
+  process_cdc_config(&xfer);
+
+  return true;
 }
 
 #endif
diff --git a/src/class/cdc/cdc_host.h b/src/class/cdc/cdc_host.h
index 33dbd2efb..a1e78f158 100644
--- a/src/class/cdc/cdc_host.h
+++ b/src/class/cdc/cdc_host.h
@@ -1,4 +1,4 @@
-/* 
+/*
  * The MIT License (MIT)
  *
  * Copyright (c) 2019 Ha Thach (tinyusb.org)
@@ -34,89 +34,148 @@
 #endif
 
 //--------------------------------------------------------------------+
-// CDC APPLICATION PUBLIC API
+// Class Driver Configuration
 //--------------------------------------------------------------------+
-/** \ingroup ClassDriver_CDC Communication Device Class (CDC)
- * \addtogroup CDC_Serial Serial
- * @{
- * \defgroup   CDC_Serial_Host Host
- * @{ */
 
-bool tuh_cdc_set_control_line_state(uint8_t dev_addr, bool dtr, bool rts, tuh_xfer_cb_t complete_cb);
+// Set Line Control state on enumeration/mounted: DTR ( bit 0), RTS (bit 1)
+#ifndef CFG_TUH_CDC_LINE_CONTROL_ON_ENUM
+#define CFG_TUH_CDC_LINE_CONTROL_ON_ENUM    0
+#endif
 
-static inline bool tuh_cdc_connect(uint8_t dev_addr, tuh_xfer_cb_t complete_cb)
-{
-  return tuh_cdc_set_control_line_state(dev_addr, true, true, complete_cb);
-}
+// Set Line Coding on enumeration/mounted, value for cdc_line_coding_t
+//#ifndef CFG_TUH_CDC_LINE_CODING_ON_ENUM
+//#define CFG_TUH_CDC_LINE_CODING_ON_ENUM   { 115200, CDC_LINE_CONDING_STOP_BITS_1, CDC_LINE_CODING_PARITY_NONE, 8 }
+//#endif
+
+// RX FIFO size
+#ifndef CFG_TUH_CDC_RX_BUFSIZE
+#define CFG_TUH_CDC_RX_BUFSIZE USBH_EPSIZE_BULK_MAX
+#endif
+
+// RX Endpoint size
+#ifndef CFG_TUH_CDC_RX_EPSIZE
+#define CFG_TUH_CDC_RX_EPSIZE  USBH_EPSIZE_BULK_MAX
+#endif
 
-static inline bool tuh_cdc_disconnect(uint8_t dev_addr, tuh_xfer_cb_t complete_cb)
+// TX FIFO size
+#ifndef CFG_TUH_CDC_TX_BUFSIZE
+#define CFG_TUH_CDC_TX_BUFSIZE USBH_EPSIZE_BULK_MAX
+#endif
+
+// TX Endpoint size
+#ifndef CFG_TUH_CDC_TX_EPSIZE
+#define CFG_TUH_CDC_TX_EPSIZE  USBH_EPSIZE_BULK_MAX
+#endif
+
+//--------------------------------------------------------------------+
+// Application API
+//--------------------------------------------------------------------+
+
+// Get Interface index from device address + interface number
+// return TUSB_INDEX_INVALID_8 (0xFF) if not found
+uint8_t tuh_cdc_itf_get_index(uint8_t daddr, uint8_t itf_num);
+
+// Get Interface information
+// return true if index is correct and interface is currently mounted
+bool tuh_cdc_itf_get_info(uint8_t idx, tuh_itf_info_t* info);
+
+// Check if a interface is mounted
+bool tuh_cdc_mounted(uint8_t idx);
+
+// Get current DTR status
+bool tuh_cdc_get_dtr(uint8_t idx);
+
+// Get current RTS status
+bool tuh_cdc_get_rts(uint8_t idx);
+
+// Check if interface is connected (DTR active)
+TU_ATTR_ALWAYS_INLINE static inline bool tuh_cdc_connected(uint8_t idx)
 {
-  return tuh_cdc_set_control_line_state(dev_addr, false, false, complete_cb);
+  return tuh_cdc_get_dtr(idx);
 }
 
-/** \brief 			Check if device support CDC Serial interface or not
- * \param[in]		dev_addr	device address
- * \retval      true if device supports
- * \retval      false if device does not support or is not mounted
- */
-bool tuh_cdc_serial_is_mounted(uint8_t dev_addr);
+// Get local (saved/cached) version of line coding.
+// This function should return correct values if tuh_cdc_set_line_coding() / tuh_cdc_get_line_coding()
+// are invoked previously or CFG_TUH_CDC_LINE_CODING_ON_ENUM is defined.
+// NOTE: This function does not make any USB transfer request to device.
+bool tuh_cdc_get_local_line_coding(uint8_t idx, cdc_line_coding_t* line_coding);
 
-/** \brief      Check if the interface is currently busy or not
- * \param[in]   dev_addr device address
- * \param[in]   pipeid value from \ref cdc_pipeid_t to indicate target pipe.
- * \retval      true if the interface is busy, meaning the stack is still transferring/waiting data from/to device
- * \retval      false if the interface is not busy, meaning the stack successfully transferred data from/to device
- * \note        This function is used to check if previous transfer is complete (success or error), so that the next transfer
- *              can be scheduled. User needs to make sure the corresponding interface is mounted
- *              (by \ref tuh_cdc_serial_is_mounted) before calling this function.
- */
-bool tuh_cdc_is_busy(uint8_t dev_addr, cdc_pipeid_t pipeid);
+//--------------------------------------------------------------------+
+// Write API
+//--------------------------------------------------------------------+
 
-/** \brief 			Perform USB OUT transfer to device
- * \param[in]		dev_addr	device address
- * \param[in]	  p_data    Buffer containing data. Must be accessible by USB controller (see \ref CFG_TUSB_MEM_SECTION)
- * \param[in]		length    Number of bytes to be transferred via USB bus
- * \retval      TUSB_ERROR_NONE on success
- * \retval      TUSB_ERROR_INTERFACE_IS_BUSY if the interface is already transferring data with device
- * \retval      TUSB_ERROR_DEVICE_NOT_READY if device is not yet configured (by SET CONFIGURED request)
- * \retval      TUSB_ERROR_INVALID_PARA if input parameters are not correct
- * \note        This function is non-blocking and returns immediately. The result of USB transfer will be reported by the
- *              interface's callback function. \a p_data must be declared with \ref CFG_TUSB_MEM_SECTION.
- */
-bool tuh_cdc_send(uint8_t dev_addr, void const * p_data, uint32_t length, bool is_notify);
+// Get the number of bytes available for writing
+uint32_t tuh_cdc_write_available(uint8_t idx);
 
-/** \brief 			Perform USB IN transfer to get data from device
- * \param[in]		dev_addr	device address
- * \param[in]	  p_buffer  Buffer containing received data. Must be accessible by USB controller (see \ref CFG_TUSB_MEM_SECTION)
- * \param[in]		length    Number of bytes to be transferred via USB bus
- * \retval      TUSB_ERROR_NONE on success
- * \retval      TUSB_ERROR_INTERFACE_IS_BUSY if the interface is already transferring data with device
- * \retval      TUSB_ERROR_DEVICE_NOT_READY if device is not yet configured (by SET CONFIGURED request)
- * \retval      TUSB_ERROR_INVALID_PARA if input parameters are not correct
- * \note        This function is non-blocking and returns immediately. The result of USB transfer will be reported by the
- *              interface's callback function. \a p_data must be declared with \ref CFG_TUSB_MEM_SECTION.
- */
-bool tuh_cdc_receive(uint8_t dev_addr, void * p_buffer, uint32_t length, bool is_notify);
+// Write to cdc interface
+uint32_t tuh_cdc_write(uint8_t idx, void const* buffer, uint32_t bufsize);
+
+// Force sending data if possible, return number of forced bytes
+uint32_t tuh_cdc_write_flush(uint8_t idx);
+
+// Clear the transmit FIFO
+bool tuh_cdc_write_clear(uint8_t idx);
+
+//--------------------------------------------------------------------+
+// Read API
+//--------------------------------------------------------------------+
+
+// Get the number of bytes available for reading
+uint32_t tuh_cdc_read_available(uint8_t idx);
+
+// Read from cdc interface
+uint32_t tuh_cdc_read (uint8_t idx, void* buffer, uint32_t bufsize);
+
+// Get a byte from RX FIFO without removing it
+bool tuh_cdc_peek(uint8_t idx, uint8_t* ch);
+
+// Clear the received FIFO
+bool tuh_cdc_read_clear (uint8_t idx);
+
+//--------------------------------------------------------------------+
+// Control Endpoint (Request) API
+// Each Function will make a USB transfer request to/from device
+//--------------------------------------------------------------------+
+
+// Request to Set Control Line State: DTR (bit 0), RTS (bit 1)
+bool tuh_cdc_set_control_line_state(uint8_t idx, uint16_t line_state, tuh_xfer_cb_t complete_cb, uintptr_t user_data);
+
+// Request to Set Line Coding
+bool tuh_cdc_set_line_coding(uint8_t idx, cdc_line_coding_t const* line_coding, tuh_xfer_cb_t complete_cb, uintptr_t user_data);
+
+// Request to Get Line Coding
+// Should only use if tuh_cdc_set_line_coding() / tuh_cdc_get_line_coding() never got invoked and
+// CFG_TUH_CDC_LINE_CODING_ON_ENUM is not defined
+// bool tuh_cdc_get_line_coding(uint8_t idx, cdc_line_coding_t* coding);
+
+// Connect by set both DTR, RTS
+static inline bool tuh_cdc_connect(uint8_t idx, tuh_xfer_cb_t complete_cb, uintptr_t user_data)
+{
+  return tuh_cdc_set_control_line_state(idx, CDC_CONTROL_LINE_STATE_DTR | CDC_CONTROL_LINE_STATE_RTS, complete_cb, user_data);
+}
+
+// Disconnect by clear both DTR, RTS
+static inline bool tuh_cdc_disconnect(uint8_t idx, tuh_xfer_cb_t complete_cb, uintptr_t user_data)
+{
+  return tuh_cdc_set_control_line_state(idx, 0x00, complete_cb, user_data);
+}
 
 //--------------------------------------------------------------------+
 // CDC APPLICATION CALLBACKS
 //--------------------------------------------------------------------+
 
-/** \brief      Callback function that is invoked when an transferring event occurred
- * \param[in]		dev_addr	Address of device
- * \param[in]   event an value from \ref xfer_result_t
- * \param[in]   pipe_id value from \ref cdc_pipeid_t indicate the pipe
- * \param[in]   xferred_bytes Number of bytes transferred via USB bus
- * \note        event can be one of following
- *              - XFER_RESULT_SUCCESS : previously scheduled transfer completes successfully.
- *              - XFER_RESULT_FAILED   : previously scheduled transfer encountered a transaction error.
- *              - XFER_RESULT_STALLED : previously scheduled transfer is stalled by device.
- * \note
- */
-void tuh_cdc_xfer_isr(uint8_t dev_addr, xfer_result_t event, cdc_pipeid_t pipe_id, uint32_t xferred_bytes);
+// Invoked when a device with CDC interface is mounted
+// idx is index of cdc interface in the internal pool.
+TU_ATTR_WEAK extern void tuh_cdc_mount_cb(uint8_t idx);
+
+// Invoked when a device with CDC interface is unmounted
+TU_ATTR_WEAK extern void tuh_cdc_umount_cb(uint8_t idx);
+
+// Invoked when received new data
+TU_ATTR_WEAK extern void tuh_cdc_rx_cb(uint8_t idx);
 
-/// @} // group CDC_Serial_Host
-/// @}
+// Invoked when a TX is complete and therefore space becomes available in TX buffer
+TU_ATTR_WEAK extern void tuh_cdc_tx_complete_cb(uint8_t idx);
 
 //--------------------------------------------------------------------+
 // Internal Class Driver API
diff --git a/src/class/cdc/cdc_rndis.h b/src/class/cdc/cdc_rndis.h
index e0f129fe3..ad153e0ac 100644
--- a/src/class/cdc/cdc_rndis.h
+++ b/src/class/cdc/cdc_rndis.h
@@ -1,4 +1,4 @@
-/* 
+/*
  * The MIT License (MIT)
  *
  * Copyright (c) 2019 Ha Thach (tinyusb.org)
diff --git a/src/class/cdc/cdc_rndis_host.c b/src/class/cdc/cdc_rndis_host.c
index 8f28f51ac..11a5355aa 100644
--- a/src/class/cdc/cdc_rndis_host.c
+++ b/src/class/cdc/cdc_rndis_host.c
@@ -1,4 +1,4 @@
-/* 
+/*
  * The MIT License (MIT)
  *
  * Copyright (c) 2019 Ha Thach (tinyusb.org)
@@ -50,8 +50,8 @@
 //--------------------------------------------------------------------+
 #define RNDIS_MSG_PAYLOAD_MAX   (1024*4)
 
-CFG_TUSB_MEM_SECTION static uint8_t msg_notification[CFG_TUH_DEVICE_MAX][8];
-CFG_TUSB_MEM_SECTION TU_ATTR_ALIGNED(4) static uint8_t msg_payload[RNDIS_MSG_PAYLOAD_MAX];
+CFG_TUH_MEM_SECTION static uint8_t msg_notification[CFG_TUH_DEVICE_MAX][8];
+CFG_TUH_MEM_SECTION CFG_TUH_MEM_ALIGN static uint8_t msg_payload[RNDIS_MSG_PAYLOAD_MAX];
 
 static rndish_data_t rndish_data[CFG_TUH_DEVICE_MAX];
 
@@ -117,7 +117,7 @@ void rndish_init(void)
 
   //------------- Task creation -------------//
 
-  //------------- semaphore creation for notificaiton pipe -------------//
+  //------------- semaphore creation for notification pipe -------------//
   for(uint8_t i=0; i<CFG_TUH_DEVICE_MAX; i++)
   {
     rndish_data[i].sem_notification_hdl = osal_semaphore_create( OSAL_SEM_REF(rndish_data[i].semaphore_notification) );
diff --git a/src/class/cdc/cdc_rndis_host.h b/src/class/cdc/cdc_rndis_host.h
index 447cc4e97..bb431ec1f 100644
--- a/src/class/cdc/cdc_rndis_host.h
+++ b/src/class/cdc/cdc_rndis_host.h
@@ -1,4 +1,4 @@
-/* 
+/*
  * The MIT License (MIT)
  *
  * Copyright (c) 2019 Ha Thach (tinyusb.org)
diff --git a/src/class/dfu/dfu_device.c b/src/class/dfu/dfu_device.c
index 8d859d2ee..464c4bd6b 100644
--- a/src/class/dfu/dfu_device.c
+++ b/src/class/dfu/dfu_device.c
@@ -56,7 +56,7 @@ typedef struct
 } dfu_state_ctx_t;
 
 // Only a single dfu state is allowed
-CFG_TUSB_MEM_SECTION static dfu_state_ctx_t _dfu_ctx;
+CFG_TUSB_MEM_SECTION tu_static dfu_state_ctx_t _dfu_ctx;
 
 static void reset_state(void)
 {
@@ -74,7 +74,7 @@ static bool process_manifest_get_status(uint8_t rhport, uint8_t stage, tusb_cont
 //--------------------------------------------------------------------+
 #if CFG_TUSB_DEBUG >= 2
 
-static tu_lookup_entry_t const _dfu_request_lookup[] =
+tu_static tu_lookup_entry_t const _dfu_request_lookup[] =
 {
   { .key = DFU_REQUEST_DETACH         , .data = "DETACH"    },
   { .key = DFU_REQUEST_DNLOAD         , .data = "DNLOAD"    },
@@ -85,13 +85,13 @@ static tu_lookup_entry_t const _dfu_request_lookup[] =
   { .key = DFU_REQUEST_ABORT          , .data = "ABORT"     },
 };
 
-static tu_lookup_table_t const _dfu_request_table =
+tu_static tu_lookup_table_t const _dfu_request_table =
 {
   .count = TU_ARRAY_SIZE(_dfu_request_lookup),
   .items = _dfu_request_lookup
 };
 
-static tu_lookup_entry_t const _dfu_state_lookup[] =
+tu_static tu_lookup_entry_t const _dfu_state_lookup[] =
 {
   { .key = APP_IDLE                   , .data = "APP_IDLE"                },
   { .key = APP_DETACH                 , .data = "APP_DETACH"              },
@@ -106,13 +106,13 @@ static tu_lookup_entry_t const _dfu_state_lookup[] =
   { .key = DFU_ERROR                  , .data = "ERROR"               },
 };
 
-static tu_lookup_table_t const _dfu_state_table =
+tu_static tu_lookup_table_t const _dfu_state_table =
 {
   .count = TU_ARRAY_SIZE(_dfu_state_lookup),
   .items = _dfu_state_lookup
 };
 
-static tu_lookup_entry_t const _dfu_status_lookup[] =
+tu_static tu_lookup_entry_t const _dfu_status_lookup[] =
 {
   { .key = DFU_STATUS_OK               , .data = "OK"              },
   { .key = DFU_STATUS_ERR_TARGET       , .data = "errTARGET"       },
@@ -132,7 +132,7 @@ static tu_lookup_entry_t const _dfu_status_lookup[] =
   { .key = DFU_STATUS_ERR_STALLEDPKT   , .data = "errSTALLEDPKT"   },
 };
 
-static tu_lookup_table_t const _dfu_status_table =
+tu_static tu_lookup_table_t const _dfu_status_table =
 {
   .count = TU_ARRAY_SIZE(_dfu_status_lookup),
   .items = _dfu_status_lookup
@@ -167,6 +167,8 @@ uint16_t dfu_moded_open(uint8_t rhport, tusb_desc_interface_t const * itf_desc,
   uint8_t alt_count = 0;
 
   uint16_t drv_len = 0;
+  TU_VERIFY(itf_desc->bInterfaceSubClass == TUD_DFU_APP_SUBCLASS && itf_desc->bInterfaceProtocol == DFU_PROTOCOL_DFU, 0);
+
   while(itf_desc->bInterfaceSubClass == TUD_DFU_APP_SUBCLASS && itf_desc->bInterfaceProtocol == DFU_PROTOCOL_DFU)
   {
     TU_ASSERT(max_len > drv_len, 0);
diff --git a/src/class/dfu/dfu_rt_device.c b/src/class/dfu/dfu_rt_device.c
index b9cd6096b..7b77b3f8f 100644
--- a/src/class/dfu/dfu_rt_device.c
+++ b/src/class/dfu/dfu_rt_device.c
@@ -110,7 +110,7 @@ bool dfu_rtd_control_xfer_cb(uint8_t rhport, uint8_t stage, tusb_control_request
       TU_LOG2("  DFU RT Request: GETSTATUS\r\n");
       dfu_status_response_t resp;
       // Status = OK, Poll timeout is ignored during RT, State = APP_IDLE, IString = 0
-      memset(&resp, 0x00, sizeof(dfu_status_response_t));
+      TU_VERIFY(tu_memset_s(&resp, sizeof(resp), 0x00, sizeof(resp))==0);
       tud_control_xfer(rhport, request, &resp, sizeof(dfu_status_response_t));
     }
     break;
diff --git a/src/class/hid/hid.h b/src/class/hid/hid.h
index 95dcc5e39..3e238966f 100644
--- a/src/class/hid/hid.h
+++ b/src/class/hid/hid.h
@@ -1,4 +1,4 @@
-/* 
+/*
  * The MIT License (MIT)
  *
  * Copyright (c) 2019 Ha Thach (tinyusb.org)
@@ -722,6 +722,7 @@ enum {
   HID_USAGE_PAGE_MSR             = 0x8e,
   HID_USAGE_PAGE_CAMERA          = 0x90,
   HID_USAGE_PAGE_ARCADE          = 0x91,
+  HID_USAGE_PAGE_FIDO            = 0xF1D0, // FIDO alliance HID usage page
   HID_USAGE_PAGE_VENDOR          = 0xFF00 // 0xFF00 - 0xFFFF
 };
 
@@ -858,6 +859,14 @@ enum
   HID_USAGE_CONSUMER_AC_PAN                            = 0x0238,
 };
 
+/// HID Usage Table: FIDO Alliance Page (0xF1D0)
+enum
+{
+  HID_USAGE_FIDO_U2FHID   = 0x01, // U2FHID usage for top-level collection
+  HID_USAGE_FIDO_DATA_IN  = 0x20, // Raw IN data report
+  HID_USAGE_FIDO_DATA_OUT = 0x21  // Raw OUT data report
+};
+
 /*--------------------------------------------------------------------
  * ASCII to KEYCODE Conversion
  *  Expand to array of [128][2] (shift, keycode)
diff --git a/src/class/hid/hid_device.c b/src/class/hid/hid_device.c
index 562ca7f36..9240fe2ca 100644
--- a/src/class/hid/hid_device.c
+++ b/src/class/hid/hid_device.c
@@ -58,7 +58,7 @@ typedef struct
   tusb_hid_descriptor_hid_t const * hid_descriptor;
 } hidd_interface_t;
 
-CFG_TUSB_MEM_SECTION static hidd_interface_t _hidd_itf[CFG_TUD_HID];
+CFG_TUSB_MEM_SECTION tu_static hidd_interface_t _hidd_itf[CFG_TUD_HID];
 
 /*------------- Helpers -------------*/
 static inline uint8_t get_index_by_itfnum(uint8_t itf_num)
@@ -76,11 +76,12 @@ static inline uint8_t get_index_by_itfnum(uint8_t itf_num)
 //--------------------------------------------------------------------+
 bool tud_hid_n_ready(uint8_t instance)
 {
+  uint8_t const rhport = 0;
   uint8_t const ep_in = _hidd_itf[instance].ep_in;
-  return tud_ready() && (ep_in != 0) && !usbd_edpt_busy(TUD_OPT_RHPORT, ep_in);
+  return tud_ready() && (ep_in != 0) && !usbd_edpt_busy(rhport, ep_in);
 }
 
-bool tud_hid_n_report(uint8_t instance, uint8_t report_id, void const* report, uint8_t len)
+bool tud_hid_n_report(uint8_t instance, uint8_t report_id, void const* report, uint16_t len)
 {
   uint8_t const rhport = 0;
   hidd_interface_t * p_hid = &_hidd_itf[instance];
@@ -91,19 +92,15 @@ bool tud_hid_n_report(uint8_t instance, uint8_t report_id, void const* report, u
   // prepare data
   if (report_id)
   {
-    len = tu_min8(len, CFG_TUD_HID_EP_BUFSIZE-1);
-
     p_hid->epin_buf[0] = report_id;
-    memcpy(p_hid->epin_buf+1, report, len);
+    TU_VERIFY(0 == tu_memcpy_s(p_hid->epin_buf+1, CFG_TUD_HID_EP_BUFSIZE-1, report, len));
     len++;
   }else
   {
-    // If report id = 0, skip ID field
-    len = tu_min8(len, CFG_TUD_HID_EP_BUFSIZE);
-    memcpy(p_hid->epin_buf, report, len);
+    TU_VERIFY(0 == tu_memcpy_s(p_hid->epin_buf, CFG_TUD_HID_EP_BUFSIZE, report, len));
   }
 
-  return usbd_edpt_xfer(TUD_OPT_RHPORT, p_hid->ep_in, p_hid->epin_buf, len);
+  return usbd_edpt_xfer(rhport, p_hid->ep_in, p_hid->epin_buf, len);
 }
 
 uint8_t tud_hid_n_interface_protocol(uint8_t instance)
@@ -125,7 +122,7 @@ bool tud_hid_n_keyboard_report(uint8_t instance, uint8_t report_id, uint8_t modi
 
   if ( keycode )
   {
-    memcpy(report.keycode, keycode, 6);
+    memcpy(report.keycode, keycode, sizeof(report.keycode));
   }else
   {
     tu_memclr(report.keycode, 6);
@@ -150,8 +147,7 @@ bool tud_hid_n_mouse_report(uint8_t instance, uint8_t report_id,
 }
 
 bool tud_hid_n_gamepad_report(uint8_t instance, uint8_t report_id,
-                              int8_t x, int8_t y, int8_t z, int8_t rz, int8_t rx, int8_t ry, uint8_t hat, uint32_t buttons)
-{
+                              int8_t x, int8_t y, int8_t z, int8_t rz, int8_t rx, int8_t ry, uint8_t hat, uint32_t buttons) {
   hid_gamepad_report_t report =
   {
     .x       = x,
@@ -172,7 +168,7 @@ bool tud_hid_n_gamepad_report(uint8_t instance, uint8_t report_id,
 //--------------------------------------------------------------------+
 void hidd_init(void)
 {
-  hidd_reset(TUD_OPT_RHPORT);
+  hidd_reset(0);
 }
 
 void hidd_reset(uint8_t rhport)
@@ -182,11 +178,13 @@ void hidd_reset(uint8_t rhport)
 }
 
 uint16_t hidd_open(uint8_t rhport, tusb_desc_interface_t const * desc_itf, uint16_t max_len)
-{
+ {
   TU_VERIFY(TUSB_CLASS_HID == desc_itf->bInterfaceClass, 0);
 
   // len = interface + hid + n*endpoints
-  uint16_t const drv_len = sizeof(tusb_desc_interface_t) + sizeof(tusb_hid_descriptor_hid_t) + desc_itf->bNumEndpoints*sizeof(tusb_desc_endpoint_t);
+  uint16_t const drv_len =
+      (uint16_t) (sizeof(tusb_desc_interface_t) + sizeof(tusb_hid_descriptor_hid_t) +
+                                       desc_itf->bNumEndpoints * sizeof(tusb_desc_endpoint_t));
   TU_ASSERT(max_len >= drv_len, 0);
 
   // Find available interface
@@ -401,13 +399,13 @@ bool hidd_xfer_cb(uint8_t rhport, uint8_t ep_addr, xfer_result_t result, uint32_
   {
     if (tud_hid_report_complete_cb)
     {
-      tud_hid_report_complete_cb(instance, p_hid->epin_buf, (uint8_t) xferred_bytes);
+      tud_hid_report_complete_cb(instance, p_hid->epin_buf, (uint16_t) xferred_bytes);
     }
   }
   // Received report
   else if (ep_addr == p_hid->ep_out)
   {
-    tud_hid_set_report_cb(instance, 0, HID_REPORT_TYPE_INVALID, p_hid->epout_buf, xferred_bytes);
+    tud_hid_set_report_cb(instance, 0, HID_REPORT_TYPE_INVALID, p_hid->epout_buf, (uint16_t) xferred_bytes);
     TU_ASSERT(usbd_edpt_xfer(rhport, p_hid->ep_out, p_hid->epout_buf, sizeof(p_hid->epout_buf)));
   }
 
diff --git a/src/class/hid/hid_device.h b/src/class/hid/hid_device.h
index 547a78f4f..cb794e964 100644
--- a/src/class/hid/hid_device.h
+++ b/src/class/hid/hid_device.h
@@ -62,7 +62,7 @@ uint8_t tud_hid_n_interface_protocol(uint8_t instance);
 uint8_t tud_hid_n_get_protocol(uint8_t instance);
 
 // Send report to host
-bool tud_hid_n_report(uint8_t instance, uint8_t report_id, void const* report, uint8_t len);
+bool tud_hid_n_report(uint8_t instance, uint8_t report_id, void const* report, uint16_t len);
 
 // KEYBOARD: convenient helper to send keyboard report if application
 // use template layout report as defined by hid_keyboard_report_t
@@ -82,7 +82,7 @@ bool tud_hid_n_gamepad_report(uint8_t instance, uint8_t report_id, int8_t x, int
 static inline bool    tud_hid_ready(void);
 static inline uint8_t tud_hid_interface_protocol(void);
 static inline uint8_t tud_hid_get_protocol(void);
-static inline bool    tud_hid_report(uint8_t report_id, void const* report, uint8_t len);
+static inline bool    tud_hid_report(uint8_t report_id, void const* report, uint16_t len);
 static inline bool    tud_hid_keyboard_report(uint8_t report_id, uint8_t modifier, uint8_t keycode[6]);
 static inline bool    tud_hid_mouse_report(uint8_t report_id, uint8_t buttons, int8_t x, int8_t y, int8_t vertical, int8_t horizontal);
 static inline bool    tud_hid_gamepad_report(uint8_t report_id, int8_t x, int8_t y, int8_t z, int8_t rz, int8_t rx, int8_t ry, uint8_t hat, uint32_t buttons);
@@ -116,7 +116,7 @@ TU_ATTR_WEAK bool tud_hid_set_idle_cb(uint8_t instance, uint8_t idle_rate);
 // Invoked when sent REPORT successfully to host
 // Application can use this to send the next report
 // Note: For composite reports, report[0] is report ID
-TU_ATTR_WEAK void tud_hid_report_complete_cb(uint8_t instance, uint8_t const* report, uint8_t len);
+TU_ATTR_WEAK void tud_hid_report_complete_cb(uint8_t instance, uint8_t const* report, uint16_t len);
 
 
 //--------------------------------------------------------------------+
@@ -137,7 +137,7 @@ static inline uint8_t tud_hid_get_protocol(void)
   return tud_hid_n_get_protocol(0);
 }
 
-static inline bool tud_hid_report(uint8_t report_id, void const* report, uint8_t len)
+static inline bool tud_hid_report(uint8_t report_id, void const* report, uint16_t len)
 {
   return tud_hid_n_report(0, report_id, report, len);
 }
@@ -182,7 +182,7 @@ static inline bool  tud_hid_gamepad_report(uint8_t report_id, int8_t x, int8_t y
   HID_COLLECTION ( HID_COLLECTION_APPLICATION )                    ,\
     /* Report ID if any */\
     __VA_ARGS__ \
-    /* 8 bits Modifier Keys (Shfit, Control, Alt) */ \
+    /* 8 bits Modifier Keys (Shift, Control, Alt) */ \
     HID_USAGE_PAGE ( HID_USAGE_PAGE_KEYBOARD )                     ,\
       HID_USAGE_MIN    ( 224                                    )  ,\
       HID_USAGE_MAX    ( 231                                    )  ,\
@@ -401,6 +401,31 @@ static inline bool  tud_hid_gamepad_report(uint8_t report_id, int8_t x, int8_t y
     HID_INPUT          ( HID_DATA | HID_VARIABLE | HID_ABSOLUTE ) ,\
   HID_COLLECTION_END \
 
+// FIDO U2F Authenticator Descriptor Template
+// - 1st parameter is report size, which is 64 bytes maximum in U2F
+// - 2nd parameter is HID_REPORT_ID(n) (optional)
+#define TUD_HID_REPORT_DESC_FIDO_U2F(report_size, ...) \
+  HID_USAGE_PAGE_N ( HID_USAGE_PAGE_FIDO, 2                    ) ,\
+  HID_USAGE      ( HID_USAGE_FIDO_U2FHID                       ) ,\
+  HID_COLLECTION ( HID_COLLECTION_APPLICATION                  ) ,\
+    /* Report ID if any */ \
+    __VA_ARGS__ \
+    /* Usage Data In */ \
+    HID_USAGE         ( HID_USAGE_FIDO_DATA_IN                 ) ,\
+    HID_LOGICAL_MIN   ( 0                                      ) ,\
+    HID_LOGICAL_MAX_N ( 0xff, 2                                ) ,\
+    HID_REPORT_SIZE   ( 8                                      ) ,\
+    HID_REPORT_COUNT  ( report_size                            ) ,\
+    HID_INPUT         ( HID_DATA | HID_VARIABLE | HID_ABSOLUTE ) ,\
+    /* Usage Data Out */ \
+    HID_USAGE         ( HID_USAGE_FIDO_DATA_OUT                ) ,\
+    HID_LOGICAL_MIN   ( 0                                      ) ,\
+    HID_LOGICAL_MAX_N ( 0xff, 2                                ) ,\
+    HID_REPORT_SIZE   ( 8                                      ) ,\
+    HID_REPORT_COUNT  ( report_size                            ) ,\
+    HID_OUTPUT        ( HID_DATA | HID_VARIABLE | HID_ABSOLUTE ) ,\
+  HID_COLLECTION_END \
+
 // HID Generic Input & Output
 // - 1st parameter is report size (mandatory)
 // - 2nd parameter is report id HID_REPORT_ID(n) (optional)
diff --git a/src/class/hid/hid_host.c b/src/class/hid/hid_host.c
index ce3d1598c..a0032aeba 100644
--- a/src/class/hid/hid_host.c
+++ b/src/class/hid/hid_host.c
@@ -1,4 +1,4 @@
-/* 
+/*
  * The MIT License (MIT)
  *
  * Copyright (c) 2019 Ha Thach (tinyusb.org)
@@ -39,6 +39,8 @@
 
 typedef struct
 {
+  uint8_t daddr;
+
   uint8_t itf_num;
   uint8_t ep_in;
   uint8_t ep_out;
@@ -52,77 +54,158 @@ typedef struct
   uint16_t epin_size;
   uint16_t epout_size;
 
-  uint8_t epin_buf[CFG_TUH_HID_EPIN_BUFSIZE];
-  uint8_t epout_buf[CFG_TUH_HID_EPOUT_BUFSIZE];
+  CFG_TUH_MEM_ALIGN uint8_t epin_buf[CFG_TUH_HID_EPIN_BUFSIZE];
+  CFG_TUH_MEM_ALIGN uint8_t epout_buf[CFG_TUH_HID_EPOUT_BUFSIZE];
 } hidh_interface_t;
 
-typedef struct
+CFG_TUH_MEM_SECTION
+tu_static hidh_interface_t _hidh_itf[CFG_TUH_HID];
+
+//--------------------------------------------------------------------+
+// Helper
+//--------------------------------------------------------------------+
+
+TU_ATTR_ALWAYS_INLINE static inline
+hidh_interface_t* get_hid_itf(uint8_t daddr, uint8_t idx)
 {
-  uint8_t inst_count;
-  hidh_interface_t instances[CFG_TUH_HID];
-} hidh_device_t;
+  TU_ASSERT(daddr && idx < CFG_TUH_HID, NULL);
+  hidh_interface_t* p_hid = &_hidh_itf[idx];
+  return (p_hid->daddr == daddr) ? p_hid : NULL;
+}
+
+// Get instance ID by endpoint address
+static uint8_t get_idx_by_epaddr(uint8_t daddr, uint8_t ep_addr)
+{
+  for ( uint8_t idx = 0; idx < CFG_TUH_HID; idx++ )
+  {
+    hidh_interface_t const * p_hid = &_hidh_itf[idx];
+
+    if ( p_hid->daddr == daddr &&
+         (p_hid->ep_in == ep_addr || p_hid->ep_out == ep_addr) )
+    {
+      return idx;
+    }
+  }
 
-static hidh_device_t _hidh_dev[CFG_TUH_DEVICE_MAX];
+  return TUSB_INDEX_INVALID_8;
+}
 
-//------------- Internal prototypes -------------//
+static hidh_interface_t* find_new_itf(void)
+{
+  for(uint8_t i=0; i<CFG_TUH_HID; i++)
+  {
+    if (_hidh_itf[i].daddr == 0) return &_hidh_itf[i];
+  }
 
-// Get HID device & interface
-TU_ATTR_ALWAYS_INLINE static inline hidh_device_t* get_dev(uint8_t dev_addr);
-TU_ATTR_ALWAYS_INLINE static inline hidh_interface_t* get_instance(uint8_t dev_addr, uint8_t instance);
-static uint8_t get_instance_id_by_itfnum(uint8_t dev_addr, uint8_t itf);
-static uint8_t get_instance_id_by_epaddr(uint8_t dev_addr, uint8_t ep_addr);
+  return NULL;
+}
 
 //--------------------------------------------------------------------+
 // Interface API
 //--------------------------------------------------------------------+
 
-uint8_t tuh_hid_instance_count(uint8_t dev_addr)
+uint8_t tuh_hid_itf_get_count(uint8_t daddr)
 {
-  return get_dev(dev_addr)->inst_count;
+  uint8_t count = 0;
+
+  for(uint8_t i=0; i<CFG_TUH_HID; i++)
+  {
+    if (_hidh_itf[i].daddr == daddr) count++;
+  }
+
+  return count;
 }
 
-bool tuh_hid_mounted(uint8_t dev_addr, uint8_t instance)
+uint8_t tuh_hid_itf_get_total_count(void)
 {
-  hidh_interface_t* hid_itf = get_instance(dev_addr, instance);
-  return (hid_itf->ep_in != 0) || (hid_itf->ep_out != 0);
+  uint8_t count = 0;
+
+  for(uint8_t i=0; i<CFG_TUH_HID; i++)
+  {
+    if (_hidh_itf[i].daddr != 0) count++;
+  }
+
+  return count;
 }
 
-uint8_t tuh_hid_interface_protocol(uint8_t dev_addr, uint8_t instance)
+bool tuh_hid_mounted(uint8_t daddr, uint8_t idx)
 {
-  hidh_interface_t* hid_itf = get_instance(dev_addr, instance);
-  return hid_itf->itf_protocol;
+  hidh_interface_t* p_hid = get_hid_itf(daddr, idx);
+  return p_hid != NULL;
+}
+
+bool tuh_hid_itf_get_info(uint8_t daddr, uint8_t idx, tuh_itf_info_t* info)
+{
+  hidh_interface_t* p_hid = get_hid_itf(daddr, idx);
+  TU_VERIFY(p_hid && info);
+
+  info->daddr = daddr;
+
+  // re-construct descriptor
+  tusb_desc_interface_t* desc = &info->desc;
+  desc->bLength            = sizeof(tusb_desc_interface_t);
+  desc->bDescriptorType    = TUSB_DESC_INTERFACE;
+
+  desc->bInterfaceNumber   = p_hid->itf_num;
+  desc->bAlternateSetting  = 0;
+  desc->bNumEndpoints      = (uint8_t) ((p_hid->ep_in ? 1u : 0u) + (p_hid->ep_out ? 1u : 0u));
+  desc->bInterfaceClass    = TUSB_CLASS_HID;
+  desc->bInterfaceSubClass = (p_hid->itf_protocol ? HID_SUBCLASS_BOOT : HID_SUBCLASS_NONE);
+  desc->bInterfaceProtocol = p_hid->itf_protocol;
+  desc->iInterface         = 0; // not used yet
+
+  return true;
+}
+
+uint8_t tuh_hid_itf_get_index(uint8_t daddr, uint8_t itf_num)
+{
+  for ( uint8_t idx = 0; idx < CFG_TUH_HID; idx++ )
+  {
+    hidh_interface_t const * p_hid = &_hidh_itf[idx];
+
+    if ( p_hid->daddr == daddr && p_hid->itf_num == itf_num) return idx;
+  }
+
+  return TUSB_INDEX_INVALID_8;
+}
+
+uint8_t tuh_hid_interface_protocol(uint8_t daddr, uint8_t idx)
+{
+  hidh_interface_t* p_hid = get_hid_itf(daddr, idx);
+  return p_hid ? p_hid->itf_protocol : 0;
 }
 
 //--------------------------------------------------------------------+
 // Control Endpoint API
 //--------------------------------------------------------------------+
 
-uint8_t tuh_hid_get_protocol(uint8_t dev_addr, uint8_t instance)
+uint8_t tuh_hid_get_protocol(uint8_t daddr, uint8_t idx)
 {
-  hidh_interface_t* hid_itf = get_instance(dev_addr, instance);
-  return hid_itf->protocol_mode;
+  hidh_interface_t* p_hid = get_hid_itf(daddr, idx);
+  return p_hid ? p_hid->protocol_mode : 0;
 }
 
 static void set_protocol_complete(tuh_xfer_t* xfer)
 {
-  uint8_t const itf_num     = (uint8_t) tu_le16toh(xfer->setup->wIndex);
-  uint8_t const daddr       = xfer->daddr;
-  uint8_t const instance    = get_instance_id_by_itfnum(daddr, itf_num);
-  hidh_interface_t* hid_itf = get_instance(daddr, instance);
+  uint8_t const itf_num = (uint8_t) tu_le16toh(xfer->setup->wIndex);
+  uint8_t const daddr   = xfer->daddr;
+  uint8_t const idx     = tuh_hid_itf_get_index(daddr, itf_num);
+
+  hidh_interface_t* p_hid = get_hid_itf(daddr, idx);
+  TU_VERIFY(p_hid, );
 
   if (XFER_RESULT_SUCCESS == xfer->result)
   {
-    hid_itf->protocol_mode = (uint8_t) tu_le16toh(xfer->setup->wValue);
+    p_hid->protocol_mode = (uint8_t) tu_le16toh(xfer->setup->wValue);
   }
 
   if (tuh_hid_set_protocol_complete_cb)
   {
-    tuh_hid_set_protocol_complete_cb(daddr, instance, hid_itf->protocol_mode);
+    tuh_hid_set_protocol_complete_cb(daddr, idx, p_hid->protocol_mode);
   }
 }
 
-
-static bool _hidh_set_protocol(uint8_t dev_addr, uint8_t itf_num, uint8_t protocol, tuh_xfer_cb_t complete_cb, uintptr_t user_data)
+static bool _hidh_set_protocol(uint8_t daddr, uint8_t itf_num, uint8_t protocol, tuh_xfer_cb_t complete_cb, uintptr_t user_data)
 {
   TU_LOG2("HID Set Protocol = %d\r\n", protocol);
 
@@ -142,7 +225,7 @@ static bool _hidh_set_protocol(uint8_t dev_addr, uint8_t itf_num, uint8_t protoc
 
   tuh_xfer_t xfer =
   {
-    .daddr       = dev_addr,
+    .daddr       = daddr,
     .ep_addr     = 0,
     .setup       = &request,
     .buffer      = NULL,
@@ -150,16 +233,15 @@ static bool _hidh_set_protocol(uint8_t dev_addr, uint8_t itf_num, uint8_t protoc
     .user_data   = user_data
   };
 
-  TU_ASSERT( tuh_control_xfer(&xfer) );
-  return true;
+  return tuh_control_xfer(&xfer);
 }
 
-bool tuh_hid_set_protocol(uint8_t dev_addr, uint8_t instance, uint8_t protocol)
+bool tuh_hid_set_protocol(uint8_t daddr, uint8_t idx, uint8_t protocol)
 {
-  hidh_interface_t* hid_itf = get_instance(dev_addr, instance);
-  TU_VERIFY(hid_itf->itf_protocol != HID_ITF_PROTOCOL_NONE);
+  hidh_interface_t* p_hid = get_hid_itf(daddr, idx);
+  TU_VERIFY(p_hid && p_hid->itf_protocol != HID_ITF_PROTOCOL_NONE);
 
-  return _hidh_set_protocol(dev_addr, hid_itf->itf_num, protocol, set_protocol_complete, 0);
+  return _hidh_set_protocol(daddr, p_hid->itf_num, protocol, set_protocol_complete, 0);
 }
 
 static void set_report_complete(tuh_xfer_t* xfer)
@@ -168,20 +250,22 @@ static void set_report_complete(tuh_xfer_t* xfer)
 
   if (tuh_hid_set_report_complete_cb)
   {
-    uint8_t const itf_num     = (uint8_t) tu_le16toh(xfer->setup->wIndex);
-    uint8_t const instance    = get_instance_id_by_itfnum(xfer->daddr, itf_num);
+    uint8_t const itf_num = (uint8_t) tu_le16toh(xfer->setup->wIndex);
+    uint8_t const idx     = tuh_hid_itf_get_index(xfer->daddr, itf_num);
 
     uint8_t const report_type = tu_u16_high(xfer->setup->wValue);
     uint8_t const report_id   = tu_u16_low(xfer->setup->wValue);
 
-    tuh_hid_set_report_complete_cb(xfer->daddr, instance, report_id, report_type,
+    tuh_hid_set_report_complete_cb(xfer->daddr, idx, report_id, report_type,
                                    (xfer->result == XFER_RESULT_SUCCESS) ? xfer->setup->wLength : 0);
   }
 }
 
-bool tuh_hid_set_report(uint8_t dev_addr, uint8_t instance, uint8_t report_id, uint8_t report_type, void* report, uint16_t len)
+bool tuh_hid_set_report(uint8_t daddr, uint8_t idx, uint8_t report_id, uint8_t report_type, void* report, uint16_t len)
 {
-  hidh_interface_t* hid_itf = get_instance(dev_addr, instance);
+  hidh_interface_t* p_hid = get_hid_itf(daddr, idx);
+  TU_VERIFY(p_hid);
+
   TU_LOG2("HID Set Report: id = %u, type = %u, len = %u\r\n", report_id, report_type, len);
 
   tusb_control_request_t const request =
@@ -193,14 +277,14 @@ bool tuh_hid_set_report(uint8_t dev_addr, uint8_t instance, uint8_t report_id, u
       .direction = TUSB_DIR_OUT
     },
     .bRequest = HID_REQ_CONTROL_SET_REPORT,
-    .wValue   = tu_u16(report_type, report_id),
-    .wIndex   = hid_itf->itf_num,
+    .wValue   = tu_htole16(tu_u16(report_type, report_id)),
+    .wIndex   = tu_htole16((uint16_t)p_hid->itf_num),
     .wLength  = len
   };
 
   tuh_xfer_t xfer =
   {
-    .daddr       = dev_addr,
+    .daddr       = daddr,
     .ep_addr     = 0,
     .setup       = &request,
     .buffer      = report,
@@ -208,14 +292,14 @@ bool tuh_hid_set_report(uint8_t dev_addr, uint8_t instance, uint8_t report_id, u
     .user_data   = 0
   };
 
-  TU_ASSERT( tuh_control_xfer(&xfer) );
-  return true;
+  return tuh_control_xfer(&xfer);
 }
 
-static bool _hidh_set_idle(uint8_t dev_addr, uint8_t itf_num, uint16_t idle_rate, tuh_xfer_cb_t complete_cb, uintptr_t user_data)
+static bool _hidh_set_idle(uint8_t daddr, uint8_t itf_num, uint16_t idle_rate, tuh_xfer_cb_t complete_cb, uintptr_t user_data)
 {
   // SET IDLE request, device can stall if not support this request
   TU_LOG2("HID Set Idle \r\n");
+
   tusb_control_request_t const request =
   {
     .bmRequestType_bit =
@@ -225,14 +309,14 @@ static bool _hidh_set_idle(uint8_t dev_addr, uint8_t itf_num, uint16_t idle_rate
       .direction = TUSB_DIR_OUT
     },
     .bRequest = HID_REQ_CONTROL_SET_IDLE,
-    .wValue   = idle_rate,
-    .wIndex   = itf_num,
+    .wValue   = tu_htole16(idle_rate),
+    .wIndex   = tu_htole16((uint16_t)itf_num),
     .wLength  = 0
   };
 
   tuh_xfer_t xfer =
   {
-    .daddr       = dev_addr,
+    .daddr       = daddr,
     .ep_addr     = 0,
     .setup       = &request,
     .buffer      = NULL,
@@ -240,25 +324,24 @@ static bool _hidh_set_idle(uint8_t dev_addr, uint8_t itf_num, uint16_t idle_rate
     .user_data   = user_data
   };
 
-  TU_ASSERT( tuh_control_xfer(&xfer) );
-
-  return true;
+  return tuh_control_xfer(&xfer);
 }
 
 //--------------------------------------------------------------------+
 // Interrupt Endpoint API
 //--------------------------------------------------------------------+
 
-bool tuh_hid_receive_report(uint8_t dev_addr, uint8_t instance)
+bool tuh_hid_receive_report(uint8_t daddr, uint8_t idx)
 {
-  hidh_interface_t* hid_itf = get_instance(dev_addr, instance);
+  hidh_interface_t* p_hid = get_hid_itf(daddr, idx);
+  TU_VERIFY(p_hid);
 
   // claim endpoint
-  TU_VERIFY( usbh_edpt_claim(dev_addr, hid_itf->ep_in) );
+  TU_VERIFY( usbh_edpt_claim(daddr, p_hid->ep_in) );
 
-  if ( !usbh_edpt_xfer(dev_addr, hid_itf->ep_in, hid_itf->epin_buf, hid_itf->epin_size) )
+  if ( !usbh_edpt_xfer(daddr, p_hid->ep_in, p_hid->epin_buf, p_hid->epin_size) )
   {
-    usbh_edpt_claim(dev_addr, hid_itf->ep_in);
+    usbh_edpt_release(daddr, p_hid->ep_in);
     return false;
   }
 
@@ -273,66 +356,111 @@ bool tuh_hid_receive_report(uint8_t dev_addr, uint8_t instance)
 //  return !usbh_edpt_busy(dev_addr, hid_itf->ep_in);
 //}
 
-//void tuh_hid_send_report(uint8_t dev_addr, uint8_t instance, uint8_t report_id, uint8_t const* report, uint16_t len);
+bool tuh_hid_send_report(uint8_t daddr, uint8_t idx, uint8_t report_id, const void* report, uint16_t len)
+{
+  TU_LOG2("HID Send Report %d\r\n", report_id);
+
+  hidh_interface_t* p_hid = get_hid_itf(daddr, idx);
+  TU_VERIFY(p_hid);
+
+  if (p_hid->ep_out == 0)
+  {
+    // This HID does not have an out endpoint (other than control)
+    return false;
+  }
+  else if (len > CFG_TUH_HID_EPOUT_BUFSIZE ||
+           (report_id != 0 && len > (CFG_TUH_HID_EPOUT_BUFSIZE - 1)))
+  {
+    // ep_out buffer is not large enough to hold contents
+    return false;
+  }
+
+  // claim endpoint
+  TU_VERIFY( usbh_edpt_claim(daddr, p_hid->ep_out) );
+
+  if (report_id == 0)
+  {
+    // No report ID in transmission
+    memcpy(&p_hid->epout_buf[0], report, len);
+  }
+  else
+  {
+    p_hid->epout_buf[0] = report_id;
+    memcpy(&p_hid->epout_buf[1], report, len);
+    ++len; // 1 more byte for report_id
+  }
+
+  TU_LOG3_MEM(p_hid->epout_buf, len, 2);
+
+  if ( !usbh_edpt_xfer(daddr, p_hid->ep_out, p_hid->epout_buf, len) )
+  {
+    usbh_edpt_release(daddr, p_hid->ep_out);
+    return false;
+  }
+
+  return true;
+}
 
 //--------------------------------------------------------------------+
 // USBH API
 //--------------------------------------------------------------------+
 void hidh_init(void)
 {
-  tu_memclr(_hidh_dev, sizeof(_hidh_dev));
+  tu_memclr(_hidh_itf, sizeof(_hidh_itf));
 }
 
-bool hidh_xfer_cb(uint8_t dev_addr, uint8_t ep_addr, xfer_result_t result, uint32_t xferred_bytes)
+bool hidh_xfer_cb(uint8_t daddr, uint8_t ep_addr, xfer_result_t result, uint32_t xferred_bytes)
 {
   (void) result;
 
   uint8_t const dir = tu_edpt_dir(ep_addr);
-  uint8_t const instance = get_instance_id_by_epaddr(dev_addr, ep_addr);
-  hidh_interface_t* hid_itf = get_instance(dev_addr, instance);
+  uint8_t const idx = get_idx_by_epaddr(daddr, ep_addr);
+
+  hidh_interface_t* p_hid = get_hid_itf(daddr, idx);
+  TU_VERIFY(p_hid);
 
   if ( dir == TUSB_DIR_IN )
   {
-    TU_LOG2("  Get Report callback (%u, %u)\r\n", dev_addr, instance);
-    TU_LOG3_MEM(hid_itf->epin_buf, xferred_bytes, 2);
-    tuh_hid_report_received_cb(dev_addr, instance, hid_itf->epin_buf, xferred_bytes);
+    TU_LOG2("  Get Report callback (%u, %u)\r\n", daddr, idx);
+    TU_LOG3_MEM(p_hid->epin_buf, xferred_bytes, 2);
+    tuh_hid_report_received_cb(daddr, idx, p_hid->epin_buf, (uint16_t) xferred_bytes);
   }else
   {
-    if (tuh_hid_report_sent_cb) tuh_hid_report_sent_cb(dev_addr, instance, hid_itf->epout_buf, xferred_bytes);
+    if (tuh_hid_report_sent_cb) tuh_hid_report_sent_cb(daddr, idx, p_hid->epout_buf, (uint16_t) xferred_bytes);
   }
 
   return true;
 }
 
-void hidh_close(uint8_t dev_addr)
+void hidh_close(uint8_t daddr)
 {
-  TU_VERIFY(dev_addr <= CFG_TUH_DEVICE_MAX, );
-
-  hidh_device_t* hid_dev = get_dev(dev_addr);
-
-  if (tuh_hid_umount_cb)
+  for(uint8_t i=0; i<CFG_TUH_HID; i++)
   {
-    for (uint8_t inst = 0; inst < hid_dev->inst_count; inst++ ) tuh_hid_umount_cb(dev_addr, inst);
+    hidh_interface_t* p_hid = &_hidh_itf[i];
+    if (p_hid->daddr == daddr)
+    {
+       if(tuh_hid_umount_cb) tuh_hid_umount_cb(daddr, i);
+       p_hid->daddr = 0;
+    }
   }
-
-  tu_memclr(hid_dev, sizeof(hidh_device_t));
 }
 
 //--------------------------------------------------------------------+
 // Enumeration
 //--------------------------------------------------------------------+
 
-bool hidh_open(uint8_t rhport, uint8_t dev_addr, tusb_desc_interface_t const *desc_itf, uint16_t max_len)
+bool hidh_open(uint8_t rhport, uint8_t daddr, tusb_desc_interface_t const *desc_itf, uint16_t max_len)
 {
   (void) rhport;
   (void) max_len;
 
   TU_VERIFY(TUSB_CLASS_HID == desc_itf->bInterfaceClass);
 
-  TU_LOG2("HID opening Interface %u (addr = %u)\r\n", desc_itf->bInterfaceNumber, dev_addr);
+  TU_LOG2("[%u] HID opening Interface %u\r\n", daddr, desc_itf->bInterfaceNumber);
 
   // len = interface + hid + n*endpoints
-  uint16_t const drv_len = sizeof(tusb_desc_interface_t) + sizeof(tusb_hid_descriptor_hid_t) + desc_itf->bNumEndpoints*sizeof(tusb_desc_endpoint_t);
+  uint16_t const drv_len = (uint16_t) (sizeof(tusb_desc_interface_t) + sizeof(tusb_hid_descriptor_hid_t) +
+                                       desc_itf->bNumEndpoints * sizeof(tusb_desc_endpoint_t));
   TU_ASSERT(max_len >= drv_len);
 
   uint8_t const *p_desc = (uint8_t const *) desc_itf;
@@ -342,12 +470,9 @@ bool hidh_open(uint8_t rhport, uint8_t dev_addr, tusb_desc_interface_t const *de
   tusb_hid_descriptor_hid_t const *desc_hid = (tusb_hid_descriptor_hid_t const *) p_desc;
   TU_ASSERT(HID_DESC_TYPE_HID == desc_hid->bDescriptorType);
 
-  // not enough interface, try to increase CFG_TUH_HID
-  // TODO multiple devices
-  hidh_device_t* hid_dev = get_dev(dev_addr);
-  TU_ASSERT(hid_dev->inst_count < CFG_TUH_HID, 0);
-
-  hidh_interface_t* hid_itf = get_instance(dev_addr, hid_dev->inst_count);  
+  hidh_interface_t* p_hid = find_new_itf();
+  TU_ASSERT(p_hid); // not enough interface, try to increase CFG_TUH_HID
+  p_hid->daddr = daddr;
 
   //------------- Endpoint Descriptors -------------//
   p_desc = tu_desc_next(p_desc);
@@ -356,34 +481,35 @@ bool hidh_open(uint8_t rhport, uint8_t dev_addr, tusb_desc_interface_t const *de
   for(int i = 0; i < desc_itf->bNumEndpoints; i++)
   {
     TU_ASSERT(TUSB_DESC_ENDPOINT == desc_ep->bDescriptorType);
-    TU_ASSERT( tuh_edpt_open(dev_addr, desc_ep) );
+    TU_ASSERT( tuh_edpt_open(daddr, desc_ep) );
 
     if(tu_edpt_dir(desc_ep->bEndpointAddress) == TUSB_DIR_IN)
     {
-      hid_itf->ep_in     = desc_ep->bEndpointAddress;
-      hid_itf->epin_size = tu_edpt_packet_size(desc_ep);
+      p_hid->ep_in     = desc_ep->bEndpointAddress;
+      p_hid->epin_size = tu_edpt_packet_size(desc_ep);
     }
     else
     {
-      hid_itf->ep_out     = desc_ep->bEndpointAddress;
-      hid_itf->epout_size = tu_edpt_packet_size(desc_ep);
+      p_hid->ep_out     = desc_ep->bEndpointAddress;
+      p_hid->epout_size = tu_edpt_packet_size(desc_ep);
     }
 
     p_desc = tu_desc_next(p_desc);
     desc_ep = (tusb_desc_endpoint_t const *) p_desc;
   }
 
-  hid_dev->inst_count++;
-
-  hid_itf->itf_num   = desc_itf->bInterfaceNumber;
+  p_hid->itf_num   = desc_itf->bInterfaceNumber;
 
   // Assume bNumDescriptors = 1
-  hid_itf->report_desc_type = desc_hid->bReportType;
-  hid_itf->report_desc_len  = tu_unaligned_read16(&desc_hid->wReportLength);
+  p_hid->report_desc_type = desc_hid->bReportType;
+  p_hid->report_desc_len  = tu_unaligned_read16(&desc_hid->wReportLength);
 
   // Per HID Specs: default is Report protocol, though we will force Boot protocol when set_config
-  hid_itf->protocol_mode = HID_PROTOCOL_BOOT;
-  if ( HID_SUBCLASS_BOOT == desc_itf->bInterfaceSubClass ) hid_itf->itf_protocol = desc_itf->bInterfaceProtocol;
+  p_hid->protocol_mode = HID_PROTOCOL_BOOT;
+  if ( HID_SUBCLASS_BOOT == desc_itf->bInterfaceSubClass )
+  {
+    p_hid->itf_protocol = desc_itf->bInterfaceProtocol;
+  }
 
   return true;
 }
@@ -399,16 +525,16 @@ enum {
   CONFIG_COMPLETE
 };
 
-static void config_driver_mount_complete(uint8_t dev_addr, uint8_t instance, uint8_t const* desc_report, uint16_t desc_len);
+static void config_driver_mount_complete(uint8_t daddr, uint8_t idx, uint8_t const* desc_report, uint16_t desc_len);
 static void process_set_config(tuh_xfer_t* xfer);
 
-bool hidh_set_config(uint8_t dev_addr, uint8_t itf_num)
+bool hidh_set_config(uint8_t daddr, uint8_t itf_num)
 {
   tusb_control_request_t request;
   request.wIndex = tu_htole16((uint16_t) itf_num);
 
   tuh_xfer_t xfer;
-  xfer.daddr     = dev_addr;
+  xfer.daddr     = daddr;
   xfer.result    = XFER_RESULT_SUCCESS;
   xfer.setup     = &request;
   xfer.user_data = CONFG_SET_IDLE;
@@ -421,8 +547,10 @@ bool hidh_set_config(uint8_t dev_addr, uint8_t itf_num)
 
 static void process_set_config(tuh_xfer_t* xfer)
 {
-  // Stall is a valid response for SET_IDLE, therefore we could ignore its result
-  if ( xfer->setup->bRequest != HID_REQ_CONTROL_SET_IDLE )
+  // Stall is a valid response for SET_IDLE, sometime SET_PROTOCOL as well
+  // therefore we could ignore its result
+  if ( !(xfer->setup->bRequest == HID_REQ_CONTROL_SET_IDLE ||
+         xfer->setup->bRequest == HID_REQ_CONTROL_SET_PROTOCOL) )
   {
     TU_ASSERT(xfer->result == XFER_RESULT_SUCCESS, );
   }
@@ -431,8 +559,9 @@ static void process_set_config(tuh_xfer_t* xfer)
   uint8_t const itf_num = (uint8_t) tu_le16toh(xfer->setup->wIndex);
   uint8_t const daddr   = xfer->daddr;
 
-  uint8_t const instance    = get_instance_id_by_itfnum(daddr, itf_num);
-  hidh_interface_t* hid_itf = get_instance(daddr, instance);
+  uint8_t const idx       = tuh_hid_itf_get_index(daddr, itf_num);
+  hidh_interface_t* p_hid = get_hid_itf(daddr, idx);
+  TU_VERIFY(p_hid, );
 
   switch(state)
   {
@@ -440,27 +569,27 @@ static void process_set_config(tuh_xfer_t* xfer)
     {
       // Idle rate = 0 mean only report when there is changes
       const uint16_t idle_rate = 0;
-      const uintptr_t next_state = (hid_itf->itf_protocol != HID_ITF_PROTOCOL_NONE) ? CONFIG_SET_PROTOCOL : CONFIG_GET_REPORT_DESC;
+      const uintptr_t next_state = (p_hid->itf_protocol != HID_ITF_PROTOCOL_NONE) ? CONFIG_SET_PROTOCOL : CONFIG_GET_REPORT_DESC;
       _hidh_set_idle(daddr, itf_num, idle_rate, process_set_config, next_state);
     }
     break;
 
     case CONFIG_SET_PROTOCOL:
-      _hidh_set_protocol(daddr, hid_itf->itf_num, HID_PROTOCOL_BOOT, process_set_config, CONFIG_GET_REPORT_DESC);
+      _hidh_set_protocol(daddr, p_hid->itf_num, HID_PROTOCOL_BOOT, process_set_config, CONFIG_GET_REPORT_DESC);
     break;
 
     case CONFIG_GET_REPORT_DESC:
       // Get Report Descriptor if possible
       // using usbh enumeration buffer since report descriptor can be very long
-      if( hid_itf->report_desc_len > CFG_TUH_ENUMERATION_BUFSIZE )
+      if( p_hid->report_desc_len > CFG_TUH_ENUMERATION_BUFSIZE )
       {
-        TU_LOG2("HID Skip Report Descriptor since it is too large %u bytes\r\n", hid_itf->report_desc_len);
+        TU_LOG2("HID Skip Report Descriptor since it is too large %u bytes\r\n", p_hid->report_desc_len);
 
         // Driver is mounted without report descriptor
-        config_driver_mount_complete(daddr, instance, NULL, 0);
+        config_driver_mount_complete(daddr, idx, NULL, 0);
       }else
       {
-        tuh_descriptor_get_hid_report(daddr, itf_num, hid_itf->report_desc_type, 0, usbh_get_enum_buf(), hid_itf->report_desc_len, process_set_config, CONFIG_COMPLETE);
+        tuh_descriptor_get_hid_report(daddr, itf_num, p_hid->report_desc_type, 0, usbh_get_enum_buf(), p_hid->report_desc_len, process_set_config, CONFIG_COMPLETE);
       }
       break;
 
@@ -469,7 +598,7 @@ static void process_set_config(tuh_xfer_t* xfer)
       uint8_t const* desc_report = usbh_get_enum_buf();
       uint16_t const desc_len    = tu_le16toh(xfer->setup->wLength);
 
-      config_driver_mount_complete(daddr, instance, desc_report, desc_len);
+      config_driver_mount_complete(daddr, idx, desc_report, desc_len);
     }
     break;
 
@@ -477,15 +606,16 @@ static void process_set_config(tuh_xfer_t* xfer)
   }
 }
 
-static void config_driver_mount_complete(uint8_t dev_addr, uint8_t instance, uint8_t const* desc_report, uint16_t desc_len)
+static void config_driver_mount_complete(uint8_t daddr, uint8_t idx, uint8_t const* desc_report, uint16_t desc_len)
 {
-  hidh_interface_t* hid_itf = get_instance(dev_addr, instance);
+  hidh_interface_t* p_hid = get_hid_itf(daddr, idx);
+  TU_VERIFY(p_hid, );
 
   // enumeration is complete
-  tuh_hid_mount_cb(dev_addr, instance, desc_report, desc_len);
+  if (tuh_hid_mount_cb) tuh_hid_mount_cb(daddr, idx, desc_report, desc_len);
 
   // notify usbh that driver enumeration is complete
-  usbh_driver_set_config_complete(dev_addr, hid_itf->itf_num);
+  usbh_driver_set_config_complete(daddr, p_hid->itf_num);
 }
 
 //--------------------------------------------------------------------+
@@ -630,46 +760,4 @@ uint8_t tuh_hid_parse_report_descriptor(tuh_hid_report_info_t* report_info_arr,
   return report_num;
 }
 
-//--------------------------------------------------------------------+
-// Helper
-//--------------------------------------------------------------------+
-
-// Get Device by address
-TU_ATTR_ALWAYS_INLINE static inline hidh_device_t* get_dev(uint8_t dev_addr)
-{
-  return &_hidh_dev[dev_addr-1];
-}
-
-// Get Interface by instance number
-TU_ATTR_ALWAYS_INLINE static inline hidh_interface_t* get_instance(uint8_t dev_addr, uint8_t instance)
-{
-  return &_hidh_dev[dev_addr-1].instances[instance];
-}
-
-// Get instance ID by interface number
-static uint8_t get_instance_id_by_itfnum(uint8_t dev_addr, uint8_t itf)
-{
-  for ( uint8_t inst = 0; inst < CFG_TUH_HID; inst++ )
-  {
-    hidh_interface_t *hid = get_instance(dev_addr, inst);
-
-    if ( (hid->itf_num == itf) && (hid->ep_in || hid->ep_out) ) return inst;
-  }
-
-  return 0xff;
-}
-
-// Get instance ID by endpoint address
-static uint8_t get_instance_id_by_epaddr(uint8_t dev_addr, uint8_t ep_addr)
-{
-  for ( uint8_t inst = 0; inst < CFG_TUH_HID; inst++ )
-  {
-    hidh_interface_t *hid = get_instance(dev_addr, inst);
-
-    if ( (ep_addr == hid->ep_in) || ( ep_addr == hid->ep_out) ) return inst;
-  }
-
-  return 0xff;
-}
-
 #endif
diff --git a/src/class/hid/hid_host.h b/src/class/hid/hid_host.h
index fe09b03b2..c0c727e6a 100644
--- a/src/class/hid/hid_host.h
+++ b/src/class/hid/hid_host.h
@@ -1,4 +1,4 @@
-/* 
+/*
  * The MIT License (MIT)
  *
  * Copyright (c) 2019 Ha Thach (tinyusb.org)
@@ -62,14 +62,27 @@ typedef struct
 // Interface API
 //--------------------------------------------------------------------+
 
-// Get the number of HID instances
-uint8_t tuh_hid_instance_count(uint8_t dev_addr);
+// Get the number of mounted HID interfaces of a device
+uint8_t tuh_hid_itf_get_count(uint8_t dev_addr);
 
-// Check if HID instance is mounted
-bool tuh_hid_mounted(uint8_t dev_addr, uint8_t instance);
+// Get all mounted interfaces across devices
+uint8_t tuh_hid_itf_get_total_count(void);
+
+// backward compatible rename
+#define tuh_hid_instance_count    tuh_hid_itf_get_count
+
+// Get Interface information
+bool tuh_hid_itf_get_info(uint8_t daddr, uint8_t idx, tuh_itf_info_t* itf_info);
+
+// Get Interface index from device address + interface number
+// return TUSB_INDEX_INVALID_8 (0xFF) if not found
+uint8_t tuh_hid_itf_get_index(uint8_t daddr, uint8_t itf_num);
 
 // Get interface supported protocol (bInterfaceProtocol) check out hid_interface_protocol_enum_t for possible values
-uint8_t tuh_hid_interface_protocol(uint8_t dev_addr, uint8_t instance);
+uint8_t tuh_hid_interface_protocol(uint8_t dev_addr, uint8_t idx);
+
+// Check if HID interface is mounted
+bool tuh_hid_mounted(uint8_t dev_addr, uint8_t idx);
 
 // Parse report descriptor into array of report_info struct and return number of reports.
 // For complicated report, application should write its own parser.
@@ -82,31 +95,31 @@ uint8_t tuh_hid_parse_report_descriptor(tuh_hid_report_info_t* reports_info_arr,
 // Get current protocol: HID_PROTOCOL_BOOT (0) or HID_PROTOCOL_REPORT (1)
 // Note: Device will be initialized in Boot protocol for simplicity.
 //       Application can use set_protocol() to switch back to Report protocol.
-uint8_t tuh_hid_get_protocol(uint8_t dev_addr, uint8_t instance);
+uint8_t tuh_hid_get_protocol(uint8_t dev_addr, uint8_t idx);
 
 // Set protocol to HID_PROTOCOL_BOOT (0) or HID_PROTOCOL_REPORT (1)
 // This function is only supported by Boot interface (tuh_n_hid_interface_protocol() != NONE)
-bool tuh_hid_set_protocol(uint8_t dev_addr, uint8_t instance, uint8_t protocol);
+bool tuh_hid_set_protocol(uint8_t dev_addr, uint8_t idx, uint8_t protocol);
 
 // Set Report using control endpoint
-// report_type is either Intput, Output or Feature, (value from hid_report_type_t)
-bool tuh_hid_set_report(uint8_t dev_addr, uint8_t instance, uint8_t report_id, uint8_t report_type, void* report, uint16_t len);
+// report_type is either Input, Output or Feature, (value from hid_report_type_t)
+bool tuh_hid_set_report(uint8_t dev_addr, uint8_t idx, uint8_t report_id, uint8_t report_type, void* report, uint16_t len);
 
 //--------------------------------------------------------------------+
 // Interrupt Endpoint API
 //--------------------------------------------------------------------+
 
 // Check if the interface is ready to use
-//bool tuh_n_hid_n_ready(uint8_t dev_addr, uint8_t instance);
+//bool tuh_n_hid_n_ready(uint8_t dev_addr, uint8_t idx);
 
 // Try to receive next report on Interrupt Endpoint. Immediately return
 // - true If succeeded, tuh_hid_report_received_cb() callback will be invoked when report is available
 // - false if failed to queue the transfer e.g endpoint is busy
-bool tuh_hid_receive_report(uint8_t dev_addr, uint8_t instance);
+bool tuh_hid_receive_report(uint8_t dev_addr, uint8_t idx);
 
 // Send report using interrupt endpoint
 // If report_id > 0 (composite), it will be sent as 1st byte, then report contents. Otherwise only report content is sent.
-//void tuh_hid_send_report(uint8_t dev_addr, uint8_t instance, uint8_t report_id, uint8_t const* report, uint16_t len);
+bool tuh_hid_send_report(uint8_t dev_addr, uint8_t idx, uint8_t report_id, const void* report, uint16_t len);
 
 //--------------------------------------------------------------------+
 // Callbacks (Weak is optional)
@@ -117,24 +130,24 @@ bool tuh_hid_receive_report(uint8_t dev_addr, uint8_t instance);
 // can be used to parse common/simple enough descriptor.
 // Note: if report descriptor length > CFG_TUH_ENUMERATION_BUFSIZE, it will be skipped
 // therefore report_desc = NULL, desc_len = 0
-void tuh_hid_mount_cb(uint8_t dev_addr, uint8_t instance, uint8_t const* report_desc, uint16_t desc_len);
+TU_ATTR_WEAK void tuh_hid_mount_cb(uint8_t dev_addr, uint8_t idx, uint8_t const* report_desc, uint16_t desc_len);
 
 // Invoked when device with hid interface is un-mounted
-TU_ATTR_WEAK void tuh_hid_umount_cb(uint8_t dev_addr, uint8_t instance);
+TU_ATTR_WEAK void tuh_hid_umount_cb(uint8_t dev_addr, uint8_t idx);
 
 // Invoked when received report from device via interrupt endpoint
 // Note: if there is report ID (composite), it is 1st byte of report
-void tuh_hid_report_received_cb(uint8_t dev_addr, uint8_t instance, uint8_t const* report, uint16_t len);
+void tuh_hid_report_received_cb(uint8_t dev_addr, uint8_t idx, uint8_t const* report, uint16_t len);
 
 // Invoked when sent report to device successfully via interrupt endpoint
-TU_ATTR_WEAK void tuh_hid_report_sent_cb(uint8_t dev_addr, uint8_t instance, uint8_t const* report, uint16_t len);
+TU_ATTR_WEAK void tuh_hid_report_sent_cb(uint8_t dev_addr, uint8_t idx, uint8_t const* report, uint16_t len);
 
 // Invoked when Sent Report to device via either control endpoint
 // len = 0 indicate there is error in the transfer e.g stalled response
-TU_ATTR_WEAK void tuh_hid_set_report_complete_cb(uint8_t dev_addr, uint8_t instance, uint8_t report_id, uint8_t report_type, uint16_t len);
+TU_ATTR_WEAK void tuh_hid_set_report_complete_cb(uint8_t dev_addr, uint8_t idx, uint8_t report_id, uint8_t report_type, uint16_t len);
 
 // Invoked when Set Protocol request is complete
-TU_ATTR_WEAK void tuh_hid_set_protocol_complete_cb(uint8_t dev_addr, uint8_t instance, uint8_t protocol);
+TU_ATTR_WEAK void tuh_hid_set_protocol_complete_cb(uint8_t dev_addr, uint8_t idx, uint8_t protocol);
 
 //--------------------------------------------------------------------+
 // Internal Class Driver API
diff --git a/src/class/midi/midi.h b/src/class/midi/midi.h
index 74dc41749..8b78c6555 100644
--- a/src/class/midi/midi.h
+++ b/src/class/midi/midi.h
@@ -1,4 +1,4 @@
-/* 
+/*
  * The MIT License (MIT)
  *
  * Copyright (c) 2019 Ha Thach (tinyusb.org)
diff --git a/src/class/midi/midi_device.c b/src/class/midi/midi_device.c
index 2ce1376bd..e3e7826da 100644
--- a/src/class/midi/midi_device.c
+++ b/src/class/midi/midi_device.c
@@ -1,4 +1,4 @@
-/* 
+/*
  * The MIT License (MIT)
  *
  * Copyright (c) 2019 Ha Thach (tinyusb.org)
@@ -92,7 +92,7 @@ bool tud_midi_n_mounted (uint8_t itf)
 
 static void _prep_out_transaction (midid_interface_t* p_midi)
 {
-  uint8_t const rhport = TUD_OPT_RHPORT;
+  uint8_t const rhport = 0;
   uint16_t available = tu_fifo_remaining(&p_midi->rx_ff);
 
   // Prepare for incoming data but only allow what we can store in the ring buffer.
@@ -127,7 +127,7 @@ uint32_t tud_midi_n_available(uint8_t itf, uint8_t cable_num)
   midid_stream_t const* stream = &midi->stream_read;
 
   // when using with packet API stream total & index are both zero
-  return tu_fifo_count(&midi->rx_ff) + (stream->total - stream->index);
+  return tu_fifo_count(&midi->rx_ff) + (uint8_t) (stream->total - stream->index);
 }
 
 uint32_t tud_midi_n_stream_read(uint8_t itf, uint8_t cable_num, void* buffer, uint32_t bufsize)
@@ -179,10 +179,10 @@ uint32_t tud_midi_n_stream_read(uint8_t itf, uint8_t cable_num, void* buffer, ui
     }
 
     // Copy data up to bufsize
-    uint32_t const count = tu_min32(stream->total - stream->index, bufsize);
+    uint8_t const count = (uint8_t) tu_min32(stream->total - stream->index, bufsize);
 
     // Skip the header (1st byte) in the buffer
-    memcpy(buf8, stream->buffer + 1 + stream->index, count);
+    TU_VERIFY(0 == tu_memcpy_s(buf8, bufsize, stream->buffer + 1 + stream->index, count));
 
     total_read += count;
     stream->index += count;
@@ -219,7 +219,7 @@ static uint32_t write_flush(midid_interface_t* midi)
   // No data to send
   if ( !tu_fifo_count(&midi->tx_ff) ) return 0;
 
-  uint8_t const rhport = TUD_OPT_RHPORT;
+  uint8_t const rhport = 0;
 
   // skip if previous transfer not complete
   TU_VERIFY( usbd_edpt_claim(rhport, midi->ep_in), 0 );
@@ -261,11 +261,11 @@ uint32_t tud_midi_n_stream_write(uint8_t itf, uint8_t cable_num, uint8_t const*
       stream->buffer[1] = data;
 
       // Check to see if we're still in a SysEx transmit.
-      if ( stream->buffer[0] == MIDI_CIN_SYSEX_START )
+      if ( ((stream->buffer[0]) & 0xF) == MIDI_CIN_SYSEX_START )
       {
         if ( data == MIDI_STATUS_SYSEX_END )
         {
-          stream->buffer[0] = MIDI_CIN_SYSEX_END_1BYTE;
+          stream->buffer[0] = (uint8_t) ((cable_num << 4) | MIDI_CIN_SYSEX_END_1BYTE);
           stream->total = 2;
         }
         else
@@ -276,13 +276,13 @@ uint32_t tud_midi_n_stream_write(uint8_t itf, uint8_t cable_num, uint8_t const*
       else if ( (msg >= 0x8 && msg <= 0xB) || msg == 0xE )
       {
         // Channel Voice Messages
-        stream->buffer[0] = (cable_num << 4) | msg;
+        stream->buffer[0] = (uint8_t) ((cable_num << 4) | msg);
         stream->total = 4;
       }
       else if ( msg == 0xC || msg == 0xD)
       {
         // Channel Voice Messages, two-byte variants (Program Change and Channel Pressure)
-        stream->buffer[0] = (cable_num << 4) | msg;
+        stream->buffer[0] = (uint8_t) ((cable_num << 4) | msg);
         stream->total = 3;
       }
       else if ( msg == 0xf )
@@ -308,11 +308,12 @@ uint32_t tud_midi_n_stream_write(uint8_t itf, uint8_t cable_num, uint8_t const*
           stream->buffer[0] = MIDI_CIN_SYSEX_END_1BYTE;
           stream->total = 2;
         }
+        stream->buffer[0] |= (uint8_t)(cable_num << 4);
       }
       else
       {
         // Pack individual bytes if we don't support packing them into words.
-        stream->buffer[0] = cable_num << 4 | 0xf;
+        stream->buffer[0] = (uint8_t) (cable_num << 4 | 0xf);
         stream->buffer[2] = 0;
         stream->buffer[3] = 0;
         stream->index = 2;
@@ -328,9 +329,9 @@ uint32_t tud_midi_n_stream_write(uint8_t itf, uint8_t cable_num, uint8_t const*
       stream->index++;
 
       // See if this byte ends a SysEx.
-      if ( stream->buffer[0] == MIDI_CIN_SYSEX_START && data == MIDI_STATUS_SYSEX_END )
+      if ( (stream->buffer[0] & 0xF) == MIDI_CIN_SYSEX_START && data == MIDI_STATUS_SYSEX_END )
       {
-        stream->buffer[0] = MIDI_CIN_SYSEX_START + (stream->index - 1);
+        stream->buffer[0] = (uint8_t) ((cable_num << 4) | (MIDI_CIN_SYSEX_START + (stream->index - 1)));
         stream->total = stream->index;
       }
     }
@@ -513,7 +514,7 @@ bool midid_xfer_cb(uint8_t rhport, uint8_t ep_addr, xfer_result_t result, uint32
   // receive new data
   if ( ep_addr == p_midi->ep_out )
   {
-    tu_fifo_write_n(&p_midi->rx_ff, p_midi->epout_buf, xferred_bytes);
+    tu_fifo_write_n(&p_midi->rx_ff, p_midi->epout_buf, (uint16_t) xferred_bytes);
 
     // invoke receive callback if available
     if (tud_midi_rx_cb) tud_midi_rx_cb(itf);
diff --git a/src/class/midi/midi_device.h b/src/class/midi/midi_device.h
index 211edc8d1..1c6f996be 100644
--- a/src/class/midi/midi_device.h
+++ b/src/class/midi/midi_device.h
@@ -1,4 +1,4 @@
-/* 
+/*
  * The MIT License (MIT)
  *
  * Copyright (c) 2019 Ha Thach (tinyusb.org)
diff --git a/src/class/msc/msc.h b/src/class/msc/msc.h
index 84b6e4d79..7f25a29ba 100644
--- a/src/class/msc/msc.h
+++ b/src/class/msc/msc.h
@@ -1,4 +1,4 @@
-/* 
+/*
  * The MIT License (MIT)
  *
  * Copyright (c) 2019 Ha Thach (tinyusb.org)
diff --git a/src/class/msc/msc_device.c b/src/class/msc/msc_device.c
index 3facb76d6..159a11259 100644
--- a/src/class/msc/msc_device.c
+++ b/src/class/msc/msc_device.c
@@ -28,9 +28,9 @@
 
 #if (CFG_TUD_ENABLED && CFG_TUD_MSC)
 
+#include "device/dcd.h"         // for faking dcd_event_xfer_complete
 #include "device/usbd.h"
 #include "device/usbd_pvt.h"
-#include "device/dcd.h"         // for faking dcd_event_xfer_complete
 
 #include "msc_device.h"
 
@@ -71,8 +71,8 @@ typedef struct
   uint8_t add_sense_qualifier;
 }mscd_interface_t;
 
-CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN static mscd_interface_t _mscd_itf;
-CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN static uint8_t _mscd_buf[CFG_TUD_MSC_EP_BUFSIZE];
+CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN tu_static mscd_interface_t _mscd_itf;
+CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN tu_static uint8_t _mscd_buf[CFG_TUD_MSC_EP_BUFSIZE];
 
 //--------------------------------------------------------------------+
 // INTERNAL OBJECT & FUNCTION DECLARATION
@@ -202,7 +202,7 @@ uint8_t rdwr10_validate_cmd(msc_cbw_t const* cbw)
 //--------------------------------------------------------------------+
 #if CFG_TUSB_DEBUG >= 2
 
-TU_ATTR_UNUSED static tu_lookup_entry_t const _msc_scsi_cmd_lookup[] =
+TU_ATTR_UNUSED tu_static tu_lookup_entry_t const _msc_scsi_cmd_lookup[] =
 {
   { .key = SCSI_CMD_TEST_UNIT_READY              , .data = "Test Unit Ready" },
   { .key = SCSI_CMD_INQUIRY                      , .data = "Inquiry" },
@@ -217,7 +217,7 @@ TU_ATTR_UNUSED static tu_lookup_entry_t const _msc_scsi_cmd_lookup[] =
   { .key = SCSI_CMD_WRITE_10                     , .data = "Write10" }
 };
 
-TU_ATTR_UNUSED static tu_lookup_table_t const _msc_scsi_cmd_table =
+TU_ATTR_UNUSED tu_static tu_lookup_table_t const _msc_scsi_cmd_table =
 {
   .count = TU_ARRAY_SIZE(_msc_scsi_cmd_lookup),
   .items = _msc_scsi_cmd_lookup
@@ -463,7 +463,7 @@ bool mscd_xfer_cb(uint8_t rhport, uint8_t ep_addr, xfer_result_t event, uint32_t
           {
             // Didn't check for case 9 (Ho > Dn), which requires examining scsi command first
             // but it is OK to just receive data then responded with failed status
-            TU_ASSERT( usbd_edpt_xfer(rhport, p_msc->ep_out, _mscd_buf, p_msc->total_len) );
+            TU_ASSERT( usbd_edpt_xfer(rhport, p_msc->ep_out, _mscd_buf, (uint16_t) p_msc->total_len) );
           }
         }else
         {
@@ -473,7 +473,7 @@ bool mscd_xfer_cb(uint8_t rhport, uint8_t ep_addr, xfer_result_t event, uint32_t
           // Invoke user callback if not built-in
           if ( (resplen < 0) && (p_msc->sense_key == 0) )
           {
-            resplen = tud_msc_scsi_cb(p_cbw->lun, p_cbw->command, _mscd_buf, p_msc->total_len);
+            resplen = tud_msc_scsi_cb(p_cbw->lun, p_cbw->command, _mscd_buf, (uint16_t) p_msc->total_len);
           }
 
           if ( resplen < 0 )
@@ -506,7 +506,7 @@ bool mscd_xfer_cb(uint8_t rhport, uint8_t ep_addr, xfer_result_t event, uint32_t
             {
               // cannot return more than host expect
               p_msc->total_len = tu_min32((uint32_t) resplen, p_cbw->total_bytes);
-              TU_ASSERT( usbd_edpt_xfer(rhport, p_msc->ep_in, _mscd_buf, p_msc->total_len) );
+              TU_ASSERT( usbd_edpt_xfer(rhport, p_msc->ep_in, _mscd_buf, (uint16_t) p_msc->total_len) );
             }
           }
         }
@@ -541,7 +541,7 @@ bool mscd_xfer_cb(uint8_t rhport, uint8_t ep_addr, xfer_result_t event, uint32_t
         // OUT transfer, invoke callback if needed
         if ( !is_data_in(p_cbw->dir) )
         {
-          int32_t cb_result = tud_msc_scsi_cb(p_cbw->lun, p_cbw->command, _mscd_buf, p_msc->total_len);
+          int32_t cb_result = tud_msc_scsi_cb(p_cbw->lun, p_cbw->command, _mscd_buf, (uint16_t) p_msc->total_len);
 
           if ( cb_result < 0 )
           {
@@ -707,7 +707,7 @@ static int32_t proc_builtin_scsi(uint8_t lun, uint8_t const scsi_cmd[16], uint8_
         read_capa10.block_size = tu_htonl(block_size);
 
         resplen = sizeof(read_capa10);
-        memcpy(buffer, &read_capa10, resplen);
+        TU_VERIFY(0 == tu_memcpy_s(buffer, bufsize, &read_capa10, (size_t) resplen));
       }
     }
     break;
@@ -741,7 +741,7 @@ static int32_t proc_builtin_scsi(uint8_t lun, uint8_t const scsi_cmd[16], uint8_
         read_fmt_capa.block_size_u16 = tu_htons(block_size);
 
         resplen = sizeof(read_fmt_capa);
-        memcpy(buffer, &read_fmt_capa, resplen);
+        TU_VERIFY(0 == tu_memcpy_s(buffer, bufsize, &read_fmt_capa, (size_t) resplen));
       }
     }
     break;
@@ -764,7 +764,7 @@ static int32_t proc_builtin_scsi(uint8_t lun, uint8_t const scsi_cmd[16], uint8_
       tud_msc_inquiry_cb(lun, inquiry_rsp.vendor_id, inquiry_rsp.product_id, inquiry_rsp.product_rev);
 
       resplen = sizeof(inquiry_rsp);
-      memcpy(buffer, &inquiry_rsp, resplen);
+      TU_VERIFY(0 == tu_memcpy_s(buffer, bufsize, &inquiry_rsp, (size_t) resplen));
     }
     break;
 
@@ -788,7 +788,7 @@ static int32_t proc_builtin_scsi(uint8_t lun, uint8_t const scsi_cmd[16], uint8_
       mode_resp.write_protected = !writable;
 
       resplen = sizeof(mode_resp);
-      memcpy(buffer, &mode_resp, resplen);
+      TU_VERIFY(0 == tu_memcpy_s(buffer, bufsize, &mode_resp, (size_t) resplen));
     }
     break;
 
@@ -801,17 +801,17 @@ static int32_t proc_builtin_scsi(uint8_t lun, uint8_t const scsi_cmd[16], uint8_
       };
 
       sense_rsp.add_sense_len       = sizeof(scsi_sense_fixed_resp_t) - 8;
-      sense_rsp.sense_key           = p_msc->sense_key;
+      sense_rsp.sense_key           = (uint8_t) (p_msc->sense_key & 0x0F);
       sense_rsp.add_sense_code      = p_msc->add_sense_code;
       sense_rsp.add_sense_qualifier = p_msc->add_sense_qualifier;
 
       resplen = sizeof(sense_rsp);
-      memcpy(buffer, &sense_rsp, resplen);
+      TU_VERIFY(0 == tu_memcpy_s(buffer, bufsize, &sense_rsp, (size_t) resplen));
 
       // request sense callback could overwrite the sense data
       if (tud_msc_request_sense_cb)
       {
-        resplen = tud_msc_request_sense_cb(lun, buffer, bufsize);
+        resplen = tud_msc_request_sense_cb(lun, buffer, (uint16_t) bufsize);
       }
 
       // Clear sense data after copy
@@ -859,7 +859,7 @@ static void proc_read10_cmd(uint8_t rhport, mscd_interface_t* p_msc)
   }
   else
   {
-    TU_ASSERT( usbd_edpt_xfer(rhport, p_msc->ep_in, _mscd_buf, nbytes), );
+    TU_ASSERT( usbd_edpt_xfer(rhport, p_msc->ep_in, _mscd_buf, (uint16_t) nbytes), );
   }
 }
 
@@ -883,7 +883,7 @@ static void proc_write10_cmd(uint8_t rhport, mscd_interface_t* p_msc)
   }
 
   // remaining bytes capped at class buffer
-  int32_t nbytes = (int32_t) tu_min32(sizeof(_mscd_buf), p_cbw->total_bytes-p_msc->xferred_len);
+  uint16_t nbytes = (uint16_t) tu_min32(sizeof(_mscd_buf), p_cbw->total_bytes-p_msc->xferred_len);
 
   // Write10 callback will be called later when usb transfer complete
   TU_ASSERT( usbd_edpt_xfer(rhport, p_msc->ep_out, _mscd_buf, nbytes), );
@@ -921,14 +921,15 @@ static void proc_write10_new_data(uint8_t rhport, mscd_interface_t* p_msc, uint3
     // Application consume less than what we got (including zero)
     if ( (uint32_t) nbytes < xferred_bytes )
     {
+      uint32_t const left_over = xferred_bytes - (uint32_t) nbytes;
       if ( nbytes > 0 )
       {
-        p_msc->xferred_len += nbytes;
-        memmove(_mscd_buf, _mscd_buf+nbytes, xferred_bytes-nbytes);
+        p_msc->xferred_len += (uint16_t) nbytes;
+        memmove(_mscd_buf, _mscd_buf+nbytes, left_over);
       }
 
       // simulate an transfer complete with adjusted parameters --> callback will be invoked with adjusted parameter
-      dcd_event_xfer_complete(rhport, p_msc->ep_out, xferred_bytes-nbytes, XFER_RESULT_SUCCESS, false);
+      dcd_event_xfer_complete(rhport, p_msc->ep_out, left_over, XFER_RESULT_SUCCESS, false);
     }
     else
     {
diff --git a/src/class/msc/msc_device.h b/src/class/msc/msc_device.h
index 5839b168d..72f95be06 100644
--- a/src/class/msc/msc_device.h
+++ b/src/class/msc/msc_device.h
@@ -1,4 +1,4 @@
-/* 
+/*
  * The MIT License (MIT)
  *
  * Copyright (c) 2019 Ha Thach (tinyusb.org)
diff --git a/src/class/msc/msc_host.c b/src/class/msc/msc_host.c
index c54a63f37..1b48813ec 100644
--- a/src/class/msc/msc_host.c
+++ b/src/class/msc/msc_host.c
@@ -1,4 +1,4 @@
-/* 
+/*
  * The MIT License (MIT)
  *
  * Copyright (c) 2019 Ha Thach (tinyusb.org)
@@ -33,6 +33,11 @@
 
 #include "msc_host.h"
 
+// Debug level, TUSB_CFG_DEBUG must be at least this level for debug message
+#define MSCH_DEBUG   2
+
+#define TU_LOG_MSCH(...)   TU_LOG(MSCH_DEBUG, __VA_ARGS__)
+
 //--------------------------------------------------------------------+
 // MACRO CONSTANT TYPEDEF
 //--------------------------------------------------------------------+
@@ -64,16 +69,17 @@ typedef struct
   uint8_t stage;
   void*   buffer;
   tuh_msc_complete_cb_t complete_cb;
+  uintptr_t complete_arg;
 
-  msc_cbw_t cbw;
-  msc_csw_t csw;
+  CFG_TUH_MEM_ALIGN msc_cbw_t cbw;
+  CFG_TUH_MEM_ALIGN msc_csw_t csw;
 }msch_interface_t;
 
-CFG_TUSB_MEM_SECTION static msch_interface_t _msch_itf[CFG_TUH_DEVICE_MAX];
+CFG_TUH_MEM_SECTION static msch_interface_t _msch_itf[CFG_TUH_DEVICE_MAX];
 
 // buffer used to read scsi information when mounted
 // largest response data currently is inquiry TODO Inquiry is not part of enum anymore
-CFG_TUSB_MEM_SECTION TU_ATTR_ALIGNED(4)
+CFG_TUH_MEM_SECTION CFG_TUH_MEM_ALIGN
 static uint8_t _msch_buffer[sizeof(scsi_inquiry_resp_t)];
 
 TU_ATTR_ALWAYS_INLINE
@@ -126,7 +132,7 @@ static inline void cbw_init(msc_cbw_t *cbw, uint8_t lun)
   cbw->lun       = lun;
 }
 
-bool tuh_msc_scsi_command(uint8_t dev_addr, msc_cbw_t const* cbw, void* data, tuh_msc_complete_cb_t complete_cb)
+bool tuh_msc_scsi_command(uint8_t dev_addr, msc_cbw_t const* cbw, void* data, tuh_msc_complete_cb_t complete_cb, uintptr_t arg)
 {
   msch_interface_t* p_msc = get_itf(dev_addr);
   TU_VERIFY(p_msc->configured);
@@ -137,13 +143,14 @@ bool tuh_msc_scsi_command(uint8_t dev_addr, msc_cbw_t const* cbw, void* data, tu
   p_msc->stage = MSC_STAGE_CMD;
   p_msc->buffer = data;
   p_msc->complete_cb = complete_cb;
+  p_msc->complete_arg = arg;
 
   TU_ASSERT(usbh_edpt_xfer(dev_addr, p_msc->ep_out, (uint8_t*) &p_msc->cbw, sizeof(msc_cbw_t)));
 
   return true;
 }
 
-bool tuh_msc_read_capacity(uint8_t dev_addr, uint8_t lun, scsi_read_capacity10_resp_t* response, tuh_msc_complete_cb_t complete_cb)
+bool tuh_msc_read_capacity(uint8_t dev_addr, uint8_t lun, scsi_read_capacity10_resp_t* response, tuh_msc_complete_cb_t complete_cb, uintptr_t arg)
 {
    msch_interface_t* p_msc = get_itf(dev_addr);
    TU_VERIFY(p_msc->configured);
@@ -156,10 +163,10 @@ bool tuh_msc_read_capacity(uint8_t dev_addr, uint8_t lun, scsi_read_capacity10_r
   cbw.cmd_len    = sizeof(scsi_read_capacity10_t);
   cbw.command[0] = SCSI_CMD_READ_CAPACITY_10;
 
-  return tuh_msc_scsi_command(dev_addr, &cbw, response, complete_cb);
+  return tuh_msc_scsi_command(dev_addr, &cbw, response, complete_cb, arg);
 }
 
-bool tuh_msc_inquiry(uint8_t dev_addr, uint8_t lun, scsi_inquiry_resp_t* response, tuh_msc_complete_cb_t complete_cb)
+bool tuh_msc_inquiry(uint8_t dev_addr, uint8_t lun, scsi_inquiry_resp_t* response, tuh_msc_complete_cb_t complete_cb, uintptr_t arg)
 {
   msch_interface_t* p_msc = get_itf(dev_addr);
   TU_VERIFY(p_msc->mounted);
@@ -178,10 +185,10 @@ bool tuh_msc_inquiry(uint8_t dev_addr, uint8_t lun, scsi_inquiry_resp_t* respons
   };
   memcpy(cbw.command, &cmd_inquiry, cbw.cmd_len);
 
-  return tuh_msc_scsi_command(dev_addr, &cbw, response, complete_cb);
+  return tuh_msc_scsi_command(dev_addr, &cbw, response, complete_cb, arg);
 }
 
-bool tuh_msc_test_unit_ready(uint8_t dev_addr, uint8_t lun, tuh_msc_complete_cb_t complete_cb)
+bool tuh_msc_test_unit_ready(uint8_t dev_addr, uint8_t lun, tuh_msc_complete_cb_t complete_cb, uintptr_t arg)
 {
   msch_interface_t* p_msc = get_itf(dev_addr);
   TU_VERIFY(p_msc->configured);
@@ -195,10 +202,10 @@ bool tuh_msc_test_unit_ready(uint8_t dev_addr, uint8_t lun, tuh_msc_complete_cb_
   cbw.command[0]  = SCSI_CMD_TEST_UNIT_READY;
   cbw.command[1]  = lun; // according to wiki TODO need verification
 
-  return tuh_msc_scsi_command(dev_addr, &cbw, NULL, complete_cb);
+  return tuh_msc_scsi_command(dev_addr, &cbw, NULL, complete_cb, arg);
 }
 
-bool tuh_msc_request_sense(uint8_t dev_addr, uint8_t lun, void *resposne, tuh_msc_complete_cb_t complete_cb)
+bool tuh_msc_request_sense(uint8_t dev_addr, uint8_t lun, void *response, tuh_msc_complete_cb_t complete_cb, uintptr_t arg)
 {
   msc_cbw_t cbw;
   cbw_init(&cbw, lun);
@@ -215,34 +222,34 @@ bool tuh_msc_request_sense(uint8_t dev_addr, uint8_t lun, void *resposne, tuh_ms
 
   memcpy(cbw.command, &cmd_request_sense, cbw.cmd_len);
 
-  return tuh_msc_scsi_command(dev_addr, &cbw, resposne, complete_cb);
+  return tuh_msc_scsi_command(dev_addr, &cbw, response, complete_cb, arg);
 }
 
-bool tuh_msc_read10(uint8_t dev_addr, uint8_t lun, void * buffer, uint32_t lba, uint16_t block_count, tuh_msc_complete_cb_t complete_cb)
+bool tuh_msc_read10(uint8_t dev_addr, uint8_t lun, void * buffer, uint32_t lba, uint16_t block_count, tuh_msc_complete_cb_t complete_cb, uintptr_t arg)
 {
   msch_interface_t* p_msc = get_itf(dev_addr);
   TU_VERIFY(p_msc->mounted);
 
   msc_cbw_t cbw;
   cbw_init(&cbw, lun);
- 
+
   cbw.total_bytes = block_count*p_msc->capacity[lun].block_size;
   cbw.dir         = TUSB_DIR_IN_MASK;
   cbw.cmd_len     = sizeof(scsi_read10_t);
- 
+
   scsi_read10_t const cmd_read10 =
   {
     .cmd_code    = SCSI_CMD_READ_10,
     .lba         = tu_htonl(lba),
     .block_count = tu_htons(block_count)
   };
- 
+
   memcpy(cbw.command, &cmd_read10, cbw.cmd_len);
- 
-  return tuh_msc_scsi_command(dev_addr, &cbw, buffer, complete_cb);
+
+  return tuh_msc_scsi_command(dev_addr, &cbw, buffer, complete_cb, arg);
 }
- 
-bool tuh_msc_write10(uint8_t dev_addr, uint8_t lun, void const * buffer, uint32_t lba, uint16_t block_count, tuh_msc_complete_cb_t complete_cb)
+
+bool tuh_msc_write10(uint8_t dev_addr, uint8_t lun, void const * buffer, uint32_t lba, uint16_t block_count, tuh_msc_complete_cb_t complete_cb, uintptr_t arg)
 {
   msch_interface_t* p_msc = get_itf(dev_addr);
   TU_VERIFY(p_msc->mounted);
@@ -263,7 +270,7 @@ bool tuh_msc_write10(uint8_t dev_addr, uint8_t lun, void const * buffer, uint32_
 
   memcpy(cbw.command, &cmd_write10, cbw.cmd_len);
 
-  return tuh_msc_scsi_command(dev_addr, &cbw, (void*)(uintptr_t) buffer, complete_cb);
+  return tuh_msc_scsi_command(dev_addr, &cbw, (void*)(uintptr_t) buffer, complete_cb, arg);
 }
 
 #if 0
@@ -325,26 +332,36 @@ bool msch_xfer_cb(uint8_t dev_addr, uint8_t ep_addr, xfer_result_t event, uint32
         p_msc->stage = MSC_STAGE_DATA;
 
         uint8_t const ep_data = (cbw->dir & TUSB_DIR_IN_MASK) ? p_msc->ep_in : p_msc->ep_out;
-        TU_ASSERT(usbh_edpt_xfer(dev_addr, ep_data, p_msc->buffer, cbw->total_bytes));
+        TU_ASSERT(usbh_edpt_xfer(dev_addr, ep_data, p_msc->buffer, (uint16_t) cbw->total_bytes));
       }else
       {
         // Status stage
         p_msc->stage = MSC_STAGE_STATUS;
-        TU_ASSERT(usbh_edpt_xfer(dev_addr, p_msc->ep_in, (uint8_t*) &p_msc->csw, sizeof(msc_csw_t)));
+        TU_ASSERT(usbh_edpt_xfer(dev_addr, p_msc->ep_in, (uint8_t*) &p_msc->csw, (uint16_t) sizeof(msc_csw_t)));
       }
     break;
 
     case MSC_STAGE_DATA:
       // Status stage
       p_msc->stage = MSC_STAGE_STATUS;
-      TU_ASSERT(usbh_edpt_xfer(dev_addr, p_msc->ep_in, (uint8_t*) &p_msc->csw, sizeof(msc_csw_t)));
+      TU_ASSERT(usbh_edpt_xfer(dev_addr, p_msc->ep_in, (uint8_t*) &p_msc->csw, (uint16_t) sizeof(msc_csw_t)));
     break;
 
     case MSC_STAGE_STATUS:
       // SCSI op is complete
       p_msc->stage = MSC_STAGE_IDLE;
 
-      if (p_msc->complete_cb) p_msc->complete_cb(dev_addr, cbw, csw);
+      if (p_msc->complete_cb)
+      {
+        tuh_msc_complete_data_t const cb_data =
+        {
+          .cbw = cbw,
+          .csw = csw,
+          .scsi_data = p_msc->buffer,
+          .user_arg = p_msc->complete_arg
+        };
+        p_msc->complete_cb(dev_addr, &cb_data);
+      }
     break;
 
     // unknown state
@@ -359,9 +376,9 @@ bool msch_xfer_cb(uint8_t dev_addr, uint8_t ep_addr, xfer_result_t event, uint32
 //--------------------------------------------------------------------+
 
 static void config_get_maxlun_complete (tuh_xfer_t* xfer);
-static bool config_test_unit_ready_complete(uint8_t dev_addr, msc_cbw_t const* cbw, msc_csw_t const* csw);
-static bool config_request_sense_complete(uint8_t dev_addr, msc_cbw_t const* cbw, msc_csw_t const* csw);
-static bool config_read_capacity_complete(uint8_t dev_addr, msc_cbw_t const* cbw, msc_csw_t const* csw);
+static bool config_test_unit_ready_complete(uint8_t dev_addr, tuh_msc_complete_data_t const * cb_data);
+static bool config_request_sense_complete(uint8_t dev_addr, tuh_msc_complete_data_t const* cb_data);
+static bool config_read_capacity_complete(uint8_t dev_addr, tuh_msc_complete_data_t const* cb_data);
 
 bool msch_open(uint8_t rhport, uint8_t dev_addr, tusb_desc_interface_t const *desc_itf, uint16_t max_len)
 {
@@ -370,7 +387,7 @@ bool msch_open(uint8_t rhport, uint8_t dev_addr, tusb_desc_interface_t const *de
              MSC_PROTOCOL_BOT  == desc_itf->bInterfaceProtocol);
 
   // msc driver length is fixed
-  uint16_t const drv_len = sizeof(tusb_desc_interface_t) + desc_itf->bNumEndpoints*sizeof(tusb_desc_endpoint_t);
+  uint16_t const drv_len = (uint16_t) (sizeof(tusb_desc_interface_t) + desc_itf->bNumEndpoints * sizeof(tusb_desc_endpoint_t));
   TU_ASSERT(drv_len <= max_len);
 
   msch_interface_t* p_msc = get_itf(dev_addr);
@@ -405,7 +422,7 @@ bool msch_set_config(uint8_t dev_addr, uint8_t itf_num)
   p_msc->configured = true;
 
   //------------- Get Max Lun -------------//
-  TU_LOG2("MSC Get Max Lun\r\n");
+  TU_LOG_MSCH("MSC Get Max Lun\r\n");
   tusb_control_request_t const request =
   {
     .bmRequestType_bit =
@@ -444,39 +461,48 @@ static void config_get_maxlun_complete (tuh_xfer_t* xfer)
   p_msc->max_lun++; // MAX LUN is minus 1 by specs
 
   // TODO multiple LUN support
-  TU_LOG2("SCSI Test Unit Ready\r\n");
+  TU_LOG_MSCH("SCSI Test Unit Ready\r\n");
   uint8_t const lun = 0;
-  tuh_msc_test_unit_ready(daddr, lun, config_test_unit_ready_complete);
+  tuh_msc_test_unit_ready(daddr, lun, config_test_unit_ready_complete, 0);
 }
 
-static bool config_test_unit_ready_complete(uint8_t dev_addr, msc_cbw_t const* cbw, msc_csw_t const* csw)
+static bool config_test_unit_ready_complete(uint8_t dev_addr, tuh_msc_complete_data_t const * cb_data)
 {
+  msc_cbw_t const* cbw = cb_data->cbw;
+  msc_csw_t const* csw = cb_data->csw;
+
   if (csw->status == 0)
   {
     // Unit is ready, read its capacity
-    TU_LOG2("SCSI Read Capacity\r\n");
-    tuh_msc_read_capacity(dev_addr, cbw->lun, (scsi_read_capacity10_resp_t*) ((void*) _msch_buffer), config_read_capacity_complete);
+    TU_LOG_MSCH("SCSI Read Capacity\r\n");
+    tuh_msc_read_capacity(dev_addr, cbw->lun, (scsi_read_capacity10_resp_t*) ((void*) _msch_buffer), config_read_capacity_complete, 0);
   }else
   {
     // Note: During enumeration, some device fails Test Unit Ready and require a few retries
     // with Request Sense to start working !!
     // TODO limit number of retries
-    TU_LOG2("SCSI Request Sense\r\n");
-    TU_ASSERT(tuh_msc_request_sense(dev_addr, cbw->lun, _msch_buffer, config_request_sense_complete));
+    TU_LOG_MSCH("SCSI Request Sense\r\n");
+    TU_ASSERT(tuh_msc_request_sense(dev_addr, cbw->lun, _msch_buffer, config_request_sense_complete, 0));
   }
 
   return true;
 }
 
-static bool config_request_sense_complete(uint8_t dev_addr, msc_cbw_t const* cbw, msc_csw_t const* csw)
+static bool config_request_sense_complete(uint8_t dev_addr, tuh_msc_complete_data_t const * cb_data)
 {
+  msc_cbw_t const* cbw = cb_data->cbw;
+  msc_csw_t const* csw = cb_data->csw;
+
   TU_ASSERT(csw->status == 0);
-  TU_ASSERT(tuh_msc_test_unit_ready(dev_addr, cbw->lun, config_test_unit_ready_complete));
+  TU_ASSERT(tuh_msc_test_unit_ready(dev_addr, cbw->lun, config_test_unit_ready_complete, 0));
   return true;
 }
 
-static bool config_read_capacity_complete(uint8_t dev_addr, msc_cbw_t const* cbw, msc_csw_t const* csw)
+static bool config_read_capacity_complete(uint8_t dev_addr, tuh_msc_complete_data_t const * cb_data)
 {
+  msc_cbw_t const* cbw = cb_data->cbw;
+  msc_csw_t const* csw = cb_data->csw;
+
   TU_ASSERT(csw->status == 0);
 
   msch_interface_t* p_msc = get_itf(dev_addr);
diff --git a/src/class/msc/msc_host.h b/src/class/msc/msc_host.h
index 7718ad4fe..6c0e5c9dd 100644
--- a/src/class/msc/msc_host.h
+++ b/src/class/msc/msc_host.h
@@ -1,4 +1,4 @@
-/* 
+/*
  * The MIT License (MIT)
  *
  * Copyright (c) 2019 Ha Thach (tinyusb.org)
@@ -41,7 +41,14 @@
 #define CFG_TUH_MSC_MAXLUN  4
 #endif
 
-typedef bool (*tuh_msc_complete_cb_t)(uint8_t dev_addr, msc_cbw_t const* cbw, msc_csw_t const* csw);
+typedef struct {
+  msc_cbw_t const* cbw; // SCSI command
+  msc_csw_t const* csw; // SCSI status
+  void* scsi_data;      // SCSI Data
+  uintptr_t user_arg;   // user argument
+}tuh_msc_complete_data_t;
+
+typedef bool (*tuh_msc_complete_cb_t)(uint8_t dev_addr, tuh_msc_complete_data_t const* cb_data);
 
 //--------------------------------------------------------------------+
 // Application API
@@ -66,33 +73,33 @@ uint32_t tuh_msc_get_block_size(uint8_t dev_addr, uint8_t lun);
 // Perform a full SCSI command (cbw, data, csw) in non-blocking manner.
 // Complete callback is invoked when SCSI op is complete.
 // return true if success, false if there is already pending operation.
-bool tuh_msc_scsi_command(uint8_t dev_addr, msc_cbw_t const* cbw, void* data, tuh_msc_complete_cb_t complete_cb);
+bool tuh_msc_scsi_command(uint8_t dev_addr, msc_cbw_t const* cbw, void* data, tuh_msc_complete_cb_t complete_cb, uintptr_t arg);
 
 // Perform SCSI Inquiry command
 // Complete callback is invoked when SCSI op is complete.
-bool tuh_msc_inquiry(uint8_t dev_addr, uint8_t lun, scsi_inquiry_resp_t* response, tuh_msc_complete_cb_t complete_cb);
+bool tuh_msc_inquiry(uint8_t dev_addr, uint8_t lun, scsi_inquiry_resp_t* response, tuh_msc_complete_cb_t complete_cb, uintptr_t arg);
 
 // Perform SCSI Test Unit Ready command
 // Complete callback is invoked when SCSI op is complete.
-bool tuh_msc_test_unit_ready(uint8_t dev_addr, uint8_t lun, tuh_msc_complete_cb_t complete_cb);
+bool tuh_msc_test_unit_ready(uint8_t dev_addr, uint8_t lun, tuh_msc_complete_cb_t complete_cb, uintptr_t arg);
 
 // Perform SCSI Request Sense 10 command
 // Complete callback is invoked when SCSI op is complete.
-bool tuh_msc_request_sense(uint8_t dev_addr, uint8_t lun, void *resposne, tuh_msc_complete_cb_t complete_cb);
+bool tuh_msc_request_sense(uint8_t dev_addr, uint8_t lun, void *response, tuh_msc_complete_cb_t complete_cb, uintptr_t arg);
 
 // Perform SCSI Read 10 command. Read n blocks starting from LBA to buffer
 // Complete callback is invoked when SCSI op is complete.
-bool  tuh_msc_read10(uint8_t dev_addr, uint8_t lun, void * buffer, uint32_t lba, uint16_t block_count, tuh_msc_complete_cb_t complete_cb);
+bool tuh_msc_read10(uint8_t dev_addr, uint8_t lun, void * buffer, uint32_t lba, uint16_t block_count, tuh_msc_complete_cb_t complete_cb, uintptr_t arg);
 
 // Perform SCSI Write 10 command. Write n blocks starting from LBA to device
 // Complete callback is invoked when SCSI op is complete.
-bool tuh_msc_write10(uint8_t dev_addr, uint8_t lun, void const * buffer, uint32_t lba, uint16_t block_count, tuh_msc_complete_cb_t complete_cb);
+bool tuh_msc_write10(uint8_t dev_addr, uint8_t lun, void const * buffer, uint32_t lba, uint16_t block_count, tuh_msc_complete_cb_t complete_cb, uintptr_t arg);
 
 // Perform SCSI Read Capacity 10 command
 // Complete callback is invoked when SCSI op is complete.
 // Note: during enumeration, host stack already carried out this request. Application can retrieve capacity by
 // simply call tuh_msc_get_block_count() and tuh_msc_get_block_size()
-bool tuh_msc_read_capacity(uint8_t dev_addr, uint8_t lun, scsi_read_capacity10_resp_t* response, tuh_msc_complete_cb_t complete_cb);
+bool tuh_msc_read_capacity(uint8_t dev_addr, uint8_t lun, scsi_read_capacity10_resp_t* response, tuh_msc_complete_cb_t complete_cb, uintptr_t arg);
 
 //------------- Application Callback -------------//
 
diff --git a/src/class/net/ecm_rndis_device.c b/src/class/net/ecm_rndis_device.c
index f6b318058..8ac7cbd01 100644
--- a/src/class/net/ecm_rndis_device.c
+++ b/src/class/net/ecm_rndis_device.c
@@ -1,4 +1,4 @@
-/* 
+/*
  * The MIT License (MIT)
  *
  * Copyright (c) 2020 Peter Lawrence
@@ -51,7 +51,7 @@ typedef struct
 
   bool ecm_mode;
 
-  // Endpoint descriptor use to open/close when receving SetInterface
+  // Endpoint descriptor use to open/close when receiving SetInterface
   // TODO since configuration descriptor may not be long-lived memory, we should
   // keep a copy of endpoint attribute instead
   uint8_t const * ecm_desc_epdata;
@@ -61,8 +61,11 @@ typedef struct
 #define CFG_TUD_NET_PACKET_PREFIX_LEN sizeof(rndis_data_packet_t)
 #define CFG_TUD_NET_PACKET_SUFFIX_LEN 0
 
-CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN static uint8_t received[CFG_TUD_NET_PACKET_PREFIX_LEN + CFG_TUD_NET_MTU + CFG_TUD_NET_PACKET_PREFIX_LEN];
-CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN static uint8_t transmitted[CFG_TUD_NET_PACKET_PREFIX_LEN + CFG_TUD_NET_MTU + CFG_TUD_NET_PACKET_PREFIX_LEN];
+CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN tu_static
+uint8_t received[CFG_TUD_NET_PACKET_PREFIX_LEN + CFG_TUD_NET_MTU + CFG_TUD_NET_PACKET_PREFIX_LEN];
+
+CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN tu_static
+uint8_t transmitted[CFG_TUD_NET_PACKET_PREFIX_LEN + CFG_TUD_NET_MTU + CFG_TUD_NET_PACKET_PREFIX_LEN];
 
 struct ecm_notify_struct
 {
@@ -70,7 +73,7 @@ struct ecm_notify_struct
   uint32_t downlink, uplink;
 };
 
-static const struct ecm_notify_struct ecm_notify_nc =
+tu_static const struct ecm_notify_struct ecm_notify_nc =
 {
   .header = {
     .bmRequestType = 0xA1,
@@ -80,7 +83,7 @@ static const struct ecm_notify_struct ecm_notify_nc =
   },
 };
 
-static const struct ecm_notify_struct ecm_notify_csc =
+tu_static const struct ecm_notify_struct ecm_notify_csc =
 {
   .header = {
     .bmRequestType = 0xA1,
@@ -92,7 +95,7 @@ static const struct ecm_notify_struct ecm_notify_csc =
 };
 
 // TODO remove CFG_TUSB_MEM_SECTION, control internal buffer is already in this special section
-CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN static union
+CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN tu_static union
 {
   uint8_t rndis_buf[120];
   struct ecm_notify_struct ecm_buf;
@@ -102,26 +105,28 @@ CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN static union
 // INTERNAL OBJECT & FUNCTION DECLARATION
 //--------------------------------------------------------------------+
 // TODO remove CFG_TUSB_MEM_SECTION
-CFG_TUSB_MEM_SECTION static netd_interface_t _netd_itf;
+CFG_TUSB_MEM_SECTION tu_static netd_interface_t _netd_itf;
 
-static bool can_xmit;
+tu_static bool can_xmit;
 
 void tud_network_recv_renew(void)
 {
-  usbd_edpt_xfer(TUD_OPT_RHPORT, _netd_itf.ep_out, received, sizeof(received));
+  usbd_edpt_xfer(0, _netd_itf.ep_out, received, sizeof(received));
 }
 
 static void do_in_xfer(uint8_t *buf, uint16_t len)
 {
   can_xmit = false;
-  usbd_edpt_xfer(TUD_OPT_RHPORT, _netd_itf.ep_in, buf, len);
+  usbd_edpt_xfer(0, _netd_itf.ep_in, buf, len);
 }
 
 void netd_report(uint8_t *buf, uint16_t len)
 {
+  uint8_t const rhport = 0;
+
   // skip if previous report not yet acknowledged by host
-  if ( usbd_edpt_busy(TUD_OPT_RHPORT, _netd_itf.ep_notif) ) return;
-  usbd_edpt_xfer(TUD_OPT_RHPORT, _netd_itf.ep_notif, buf, len);
+  if ( usbd_edpt_busy(rhport, _netd_itf.ep_notif) ) return;
+  usbd_edpt_xfer(rhport, _netd_itf.ep_notif, buf, len);
 }
 
 //--------------------------------------------------------------------+
@@ -316,11 +321,11 @@ bool netd_control_xfer_cb (uint8_t rhport, uint8_t stage, tusb_control_request_t
             rndis_generic_msg_t *rndis_msg = (rndis_generic_msg_t *) ((void*) notify.rndis_buf);
             uint32_t msglen = tu_le32toh(rndis_msg->MessageLength);
             TU_ASSERT(msglen <= sizeof(notify.rndis_buf));
-            tud_control_xfer(rhport, request, notify.rndis_buf, msglen);
+            tud_control_xfer(rhport, request, notify.rndis_buf, (uint16_t) msglen);
           }
           else
           {
-            tud_control_xfer(rhport, request, notify.rndis_buf, sizeof(notify.rndis_buf));
+            tud_control_xfer(rhport, request, notify.rndis_buf, (uint16_t) sizeof(notify.rndis_buf));
           }
         }
       break;
@@ -367,7 +372,7 @@ static void handle_incoming_packet(uint32_t len)
         }
   }
 
-  if (!tud_network_recv_cb(pnt, size))
+  if (!tud_network_recv_cb(pnt, (uint16_t) size))
   {
     /* if a buffer was never handled by user code, we must renew on the user's behalf */
     tud_network_recv_renew();
diff --git a/src/class/net/ncm_device.c b/src/class/net/ncm_device.c
index 1987337f8..9e9580249 100644
--- a/src/class/net/ncm_device.c
+++ b/src/class/net/ncm_device.c
@@ -130,7 +130,7 @@ typedef struct
 // INTERNAL OBJECT & FUNCTION DECLARATION
 //--------------------------------------------------------------------+
 
-CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN static const ntb_parameters_t ntb_parameters = {
+CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN tu_static const ntb_parameters_t ntb_parameters = {
     .wLength                 = sizeof(ntb_parameters_t),
     .bmNtbFormatsSupported   = 0x01,
     .dwNtbInMaxSize          = CFG_TUD_NCM_IN_NTB_MAX_SIZE,
@@ -145,11 +145,11 @@ CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN static const ntb_parameters_t ntb_parame
     .wNtbOutMaxDatagrams     = 0
 };
 
-CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN static transmit_ntb_t transmit_ntb[2];
+CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN tu_static transmit_ntb_t transmit_ntb[2];
 
-CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN static uint8_t receive_ntb[CFG_TUD_NCM_OUT_NTB_MAX_SIZE];
+CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN tu_static uint8_t receive_ntb[CFG_TUD_NCM_OUT_NTB_MAX_SIZE];
 
-static ncm_interface_t ncm_interface;
+tu_static ncm_interface_t ncm_interface;
 
 /*
  * Set up the NTB state in ncm_interface to be ready to add datagrams.
@@ -188,7 +188,7 @@ static void ncm_start_tx(void) {
   ntb->ndp.datagram[ncm_interface.datagram_count].wDatagramLength = 0;
 
   // Kick off an endpoint transfer
-  usbd_edpt_xfer(TUD_OPT_RHPORT, ncm_interface.ep_in, ntb->data, ntb_length);
+  usbd_edpt_xfer(0, ncm_interface.ep_in, ntb->data, ntb_length);
   ncm_interface.transferring = true;
 
   // Swap to the other NTB and clear it out
@@ -196,7 +196,7 @@ static void ncm_start_tx(void) {
   ncm_prepare_for_tx();
 }
 
-static struct ecm_notify_struct ncm_notify_connected =
+tu_static struct ecm_notify_struct ncm_notify_connected =
 {
     .header = {
         .bmRequestType_bit = {
@@ -210,7 +210,7 @@ static struct ecm_notify_struct ncm_notify_connected =
     },
 };
 
-static struct ecm_notify_struct ncm_notify_speed_change =
+tu_static struct ecm_notify_struct ncm_notify_speed_change =
 {
     .header = {
         .bmRequestType_bit = {
@@ -229,7 +229,7 @@ void tud_network_recv_renew(void)
 {
   if (!ncm_interface.num_datagrams)
   {
-    usbd_edpt_xfer(TUD_OPT_RHPORT, ncm_interface.ep_out, receive_ntb, sizeof(receive_ntb));
+    usbd_edpt_xfer(0, ncm_interface.ep_out, receive_ntb, sizeof(receive_ntb));
     return;
   }
 
@@ -316,14 +316,15 @@ uint16_t netd_open(uint8_t rhport, tusb_desc_interface_t const * itf_desc, uint1
 
 static void ncm_report(void)
 {
+  uint8_t const rhport = 0;
   if (ncm_interface.report_state == REPORT_SPEED) {
     ncm_notify_speed_change.header.wIndex = ncm_interface.itf_num;
-    usbd_edpt_xfer(TUD_OPT_RHPORT, ncm_interface.ep_notif, (uint8_t *) &ncm_notify_speed_change, sizeof(ncm_notify_speed_change));
+    usbd_edpt_xfer(rhport, ncm_interface.ep_notif, (uint8_t *) &ncm_notify_speed_change, sizeof(ncm_notify_speed_change));
     ncm_interface.report_state = REPORT_CONNECTED;
     ncm_interface.report_pending = true;
   } else if (ncm_interface.report_state == REPORT_CONNECTED) {
     ncm_notify_connected.header.wIndex = ncm_interface.itf_num;
-    usbd_edpt_xfer(TUD_OPT_RHPORT, ncm_interface.ep_notif, (uint8_t *) &ncm_notify_connected, sizeof(ncm_notify_connected));
+    usbd_edpt_xfer(rhport, ncm_interface.ep_notif, (uint8_t *) &ncm_notify_connected, sizeof(ncm_notify_connected));
     ncm_interface.report_state = REPORT_DONE;
     ncm_interface.report_pending = true;
   }
@@ -391,7 +392,7 @@ bool netd_control_xfer_cb(uint8_t rhport, uint8_t stage, tusb_control_request_t
 
       if (NCM_GET_NTB_PARAMETERS == request->bRequest)
       {
-        tud_control_xfer(rhport, request, (void*)&ntb_parameters, sizeof(ntb_parameters));
+        tud_control_xfer(rhport, request, (void*)(uintptr_t) &ntb_parameters, sizeof(ntb_parameters));
       }
 
       break;
@@ -429,7 +430,7 @@ static void handle_incoming_datagram(uint32_t len)
   {
     ncm_interface.num_datagrams++;
   }
-  
+
   tud_network_recv_renew();
 }
 
diff --git a/src/class/net/net_device.h b/src/class/net/net_device.h
index 6e294465b..399916355 100644
--- a/src/class/net/net_device.h
+++ b/src/class/net/net_device.h
@@ -1,4 +1,4 @@
-/* 
+/*
  * The MIT License (MIT)
  *
  * Copyright (c) 2020 Peter Lawrence
@@ -94,7 +94,7 @@ void tud_network_init_cb(void);
 
 // client must provide this: 48-bit MAC address
 // TODO removed later since it is not part of tinyusb stack
-extern const uint8_t tud_network_mac_address[6];
+extern uint8_t tud_network_mac_address[6];
 
 //------------- NCM -------------//
 
diff --git a/src/class/usbtmc/usbtmc.h b/src/class/usbtmc/usbtmc.h
index 7d7005c2e..090ab3c4a 100644
--- a/src/class/usbtmc/usbtmc.h
+++ b/src/class/usbtmc/usbtmc.h
@@ -158,7 +158,7 @@ enum {
   USBTMC_BULK_IN_ERR_DATA_TOO_SHORT = 4u,
   USBTMC_BULK_IN_ERR_DATA_TOO_LONG = 5u,
 };
-// bult-in halt errors
+// built-in halt errors
 enum {
   USBTMC_BULK_IN_ERR = 1u, ///< receives a USBTMC command message that expects a response while a
                            /// Bulk-IN transfer is in progress
@@ -189,7 +189,10 @@ typedef enum {
   USBTMC_STATUS_FAILED = 0x80,
   USBTMC_STATUS_TRANSFER_NOT_IN_PROGRESS = 0x81,
   USBTMC_STATUS_SPLIT_NOT_IN_PROGRESS = 0x82,
-  USBTMC_STATUS_SPLIT_IN_PROGRESS  = 0x83
+  USBTMC_STATUS_SPLIT_IN_PROGRESS  = 0x83,
+
+  /****** USBTMC 488 *************/
+  USB488_STATUS_INTERRUPT_IN_BUSY = 0x20
 } usbtmc_status_enum;
 
 /************************************************************
@@ -259,14 +262,14 @@ typedef struct TU_ATTR_PACKED
 
   struct TU_ATTR_PACKED
   {
-    unsigned int listenOnly :1;
-    unsigned int talkOnly :1;
-    unsigned int supportsIndicatorPulse :1;
+    uint8_t listenOnly :1;
+    uint8_t talkOnly :1;
+    uint8_t supportsIndicatorPulse :1;
   } bmIntfcCapabilities;
 
   struct TU_ATTR_PACKED
   {
-    unsigned int canEndBulkInOnTermChar :1;
+    uint8_t canEndBulkInOnTermChar :1;
   } bmDevCapabilities;
 
   uint8_t _reserved2[6];
@@ -274,17 +277,17 @@ typedef struct TU_ATTR_PACKED
 
   struct TU_ATTR_PACKED
   {
-    unsigned int is488_2 :1;
-    unsigned int supportsREN_GTL_LLO :1;
-    unsigned int supportsTrigger :1;
+    uint8_t supportsTrigger :1;
+    uint8_t supportsREN_GTL_LLO :1;
+    uint8_t is488_2 :1;
   } bmIntfcCapabilities488;
 
   struct TU_ATTR_PACKED
   {
-    unsigned int SCPI :1;
-    unsigned int SR1 :1;
-    unsigned int RL1 :1;
-    unsigned int DT1 :1;
+    uint8_t DT1 :1;
+    uint8_t RL1 :1;
+    uint8_t SR1 :1;
+    uint8_t SCPI :1;
   } bmDevCapabilities488;
   uint8_t _reserved3[8];
 } usbtmc_response_capabilities_488_t;
@@ -313,4 +316,3 @@ typedef struct TU_ATTR_PACKED
 TU_VERIFY_STATIC(sizeof(usbtmc_read_stb_interrupt_488_t) == 2u, "struct wrong length");
 
 #endif
-
diff --git a/src/class/usbtmc/usbtmc_device.c b/src/class/usbtmc/usbtmc_device.c
index b02b07575..4e320a778 100644
--- a/src/class/usbtmc/usbtmc_device.c
+++ b/src/class/usbtmc/usbtmc_device.c
@@ -64,7 +64,8 @@
 // USBTMC 3.2.2 error conditions not strictly followed
 // No local lock-out, REN, or GTL.
 // Clear message available status byte at the correct time? (488 4.3.1.3)
-
+// Ability to defer status byte transmission
+// Transmission of status byte in response to USB488 SRQ condition
 
 #include "tusb_option.h"
 
@@ -77,9 +78,14 @@
 
 #ifdef xDEBUG
 #include "uart_util.h"
-static char logMsg[150];
+tu_static char logMsg[150];
 #endif
 
+// Buffer size must be an exact multiple of the max packet size for both
+// bulk  (up to 64 bytes for FS, 512 bytes for HS). In addation, this driver
+// imposes a minimum buffer size of 32 bytes.
+#define USBTMCD_BUFFER_SIZE (TUD_OPT_HIGH_SPEED ? 512 : 64)
+
 /*
  * The state machine does not allow simultaneous reading and writing. This is
  * consistent with USBTMC.
@@ -120,9 +126,12 @@ typedef struct
   uint8_t ep_int_in;
   // IN buffer is only used for first packet, not the remainder
   // in order to deal with prepending header
-  CFG_TUSB_MEM_ALIGN uint8_t ep_bulk_in_buf[USBTMCD_MAX_PACKET_SIZE];
+  CFG_TUSB_MEM_ALIGN uint8_t ep_bulk_in_buf[USBTMCD_BUFFER_SIZE];
+  uint32_t ep_bulk_in_wMaxPacketSize;
   // OUT buffer receives one packet at a time
-  CFG_TUSB_MEM_ALIGN uint8_t ep_bulk_out_buf[USBTMCD_MAX_PACKET_SIZE];
+  CFG_TUSB_MEM_ALIGN uint8_t ep_bulk_out_buf[USBTMCD_BUFFER_SIZE];
+  uint32_t ep_bulk_out_wMaxPacketSize;
+
   uint32_t transfer_size_remaining; // also used for requested length for bulk IN.
   uint32_t transfer_size_sent;      // To keep track of data bytes that have been queued in FIFO (not header bytes)
 
@@ -134,30 +143,31 @@ typedef struct
   usbtmc_capabilities_specific_t const * capabilities;
 } usbtmc_interface_state_t;
 
-CFG_TUSB_MEM_SECTION static usbtmc_interface_state_t usbtmc_state =
+CFG_TUSB_MEM_SECTION tu_static usbtmc_interface_state_t usbtmc_state =
 {
     .itf_id = 0xFF,
 };
 
-// We need all headers to fit in a single packet in this implementation.
-TU_VERIFY_STATIC(USBTMCD_MAX_PACKET_SIZE >= 32u,"USBTMC dev EP packet size too small");
-TU_VERIFY_STATIC(
-    (sizeof(usbtmc_state.ep_bulk_in_buf) % USBTMCD_MAX_PACKET_SIZE) == 0,
-    "packet buffer must be a multiple of the packet size");
+// We need all headers to fit in a single packet in this implementation, 32 bytes will fit all standard USBTMC headers
+TU_VERIFY_STATIC(USBTMCD_BUFFER_SIZE >= 32u,"USBTMC dev buffer size too small");
 
 static bool handle_devMsgOutStart(uint8_t rhport, void *data, size_t len);
 static bool handle_devMsgOut(uint8_t rhport, void *data, size_t len, size_t packetLen);
 
-static uint8_t termChar;
-static uint8_t termCharRequested = false;
+#ifndef NDEBUG
+tu_static uint8_t termChar;
+#endif
 
+tu_static uint8_t termCharRequested = false;
 
-osal_mutex_def_t usbtmcLockBuffer;
-static osal_mutex_t usbtmcLock;
+#if OSAL_MUTEX_REQUIRED
+static OSAL_MUTEX_DEF(usbtmcLockBuffer);
+#endif
+osal_mutex_t usbtmcLock;
 
 // Our own private lock, mostly for the state variable.
-#define criticalEnter() do {osal_mutex_lock(usbtmcLock,OSAL_TIMEOUT_WAIT_FOREVER); } while (0)
-#define criticalLeave() do {osal_mutex_unlock(usbtmcLock); } while (0)
+#define criticalEnter() do { (void) osal_mutex_lock(usbtmcLock,OSAL_TIMEOUT_WAIT_FOREVER); } while (0)
+#define criticalLeave() do { (void) osal_mutex_unlock(usbtmcLock); } while (0)
 
 bool atomicChangeState(usbtmcd_state_enum expectedState, usbtmcd_state_enum newState)
 {
@@ -282,12 +292,15 @@ uint16_t usbtmcd_open_cb(uint8_t rhport, tusb_desc_interface_t const * itf_desc,
       tusb_desc_endpoint_t const *ep_desc = (tusb_desc_endpoint_t const *)p_desc;
       switch(ep_desc->bmAttributes.xfer) {
         case TUSB_XFER_BULK:
-          TU_ASSERT(tu_edpt_packet_size(ep_desc) == USBTMCD_MAX_PACKET_SIZE, 0);
+          // Ensure  buffer is an exact multiple of the maxPacketSize
+          TU_ASSERT((USBTMCD_BUFFER_SIZE % tu_edpt_packet_size(ep_desc)) == 0, 0);
           if (tu_edpt_dir(ep_desc->bEndpointAddress) == TUSB_DIR_IN)
           {
             usbtmc_state.ep_bulk_in = ep_desc->bEndpointAddress;
+            usbtmc_state.ep_bulk_in_wMaxPacketSize = tu_edpt_packet_size(ep_desc);
           } else {
             usbtmc_state.ep_bulk_out = ep_desc->bEndpointAddress;
+            usbtmc_state.ep_bulk_out_wMaxPacketSize = tu_edpt_packet_size(ep_desc);
           }
 
           break;
@@ -354,9 +367,9 @@ bool tud_usbtmc_start_bus_read()
   case STATE_RCV:
     break;
   default:
-    TU_VERIFY(false);
+    return false;
   }
-  TU_VERIFY(usbd_edpt_xfer(usbtmc_state.rhport, usbtmc_state.ep_bulk_out, usbtmc_state.ep_bulk_out_buf, 64));
+  TU_VERIFY(usbd_edpt_xfer(usbtmc_state.rhport, usbtmc_state.ep_bulk_out, usbtmc_state.ep_bulk_out_buf, (uint16_t)usbtmc_state.ep_bulk_out_wMaxPacketSize));
   return true;
 }
 
@@ -395,7 +408,7 @@ static bool handle_devMsgOut(uint8_t rhport, void *data, size_t len, size_t pack
   // return true upon failure, as we can assume error is being handled elsewhere.
   TU_VERIFY(usbtmc_state.state == STATE_RCV,true);
 
-  bool shortPacket = (packetLen < USBTMCD_MAX_PACKET_SIZE);
+  bool shortPacket = (packetLen < usbtmc_state.ep_bulk_out_wMaxPacketSize);
 
   // Packet is to be considered complete when we get enough data or at a short packet.
   bool atEnd = false;
@@ -432,7 +445,10 @@ static bool handle_devMsgIn(void *data, size_t len)
   usbtmc_state.transfer_size_sent = 0u;
 
   termCharRequested = msg->bmTransferAttributes.TermCharEnabled;
+
+#ifndef NDEBUG
   termChar = msg->TermChar;
+#endif
 
   if(termCharRequested)
     TU_VERIFY(usbtmc_state.capabilities->bmDevCapabilities.canEndBulkInOnTermChar);
@@ -456,53 +472,53 @@ bool usbtmcd_xfer_cb(uint8_t rhport, uint8_t ep_addr, xfer_result_t result, uint
     switch(usbtmc_state.state)
     {
     case STATE_IDLE:
-      TU_VERIFY(xferred_bytes >= sizeof(usbtmc_msg_generic_t));
-      msg = (usbtmc_msg_generic_t*)(usbtmc_state.ep_bulk_out_buf);
-      uint8_t invInvTag = (uint8_t)~(msg->header.bTagInverse);
-      TU_VERIFY(msg->header.bTag == invInvTag);
-      TU_VERIFY(msg->header.bTag != 0x00);
+      {
+        TU_VERIFY(xferred_bytes >= sizeof(usbtmc_msg_generic_t));
+        msg = (usbtmc_msg_generic_t*)(usbtmc_state.ep_bulk_out_buf);
+        uint8_t invInvTag = (uint8_t)~(msg->header.bTagInverse);
+        TU_VERIFY(msg->header.bTag == invInvTag);
+        TU_VERIFY(msg->header.bTag != 0x00);
 
-      switch(msg->header.MsgID) {
-      case USBTMC_MSGID_DEV_DEP_MSG_OUT:
-        if(!handle_devMsgOutStart(rhport, msg, xferred_bytes))
-        {
-          usbd_edpt_stall(rhport, usbtmc_state.ep_bulk_out);
-          TU_VERIFY(false);
-        }
-        break;
+        switch(msg->header.MsgID) {
+        case USBTMC_MSGID_DEV_DEP_MSG_OUT:
+          if(!handle_devMsgOutStart(rhport, msg, xferred_bytes))
+          {
+            usbd_edpt_stall(rhport, usbtmc_state.ep_bulk_out);
+            return false;
+          }
+          break;
 
-      case USBTMC_MSGID_DEV_DEP_MSG_IN:
-        TU_VERIFY(handle_devMsgIn(msg, xferred_bytes));
-        break;
+        case USBTMC_MSGID_DEV_DEP_MSG_IN:
+          TU_VERIFY(handle_devMsgIn(msg, xferred_bytes));
+          break;
 
 #if (CFG_TUD_USBTMC_ENABLE_488)
-      case USBTMC_MSGID_USB488_TRIGGER:
-        // Spec says we halt the EP if we didn't declare we support it.
-        TU_VERIFY(usbtmc_state.capabilities->bmIntfcCapabilities488.supportsTrigger);
-        TU_VERIFY(tud_usbtmc_msg_trigger_cb(msg));
+        case USBTMC_MSGID_USB488_TRIGGER:
+          // Spec says we halt the EP if we didn't declare we support it.
+          TU_VERIFY(usbtmc_state.capabilities->bmIntfcCapabilities488.supportsTrigger);
+          TU_VERIFY(tud_usbtmc_msg_trigger_cb(msg));
 
-        break;
+          break;
 #endif
-      case USBTMC_MSGID_VENDOR_SPECIFIC_MSG_OUT:
-      case USBTMC_MSGID_VENDOR_SPECIFIC_IN:
-      default:
-        usbd_edpt_stall(rhport, usbtmc_state.ep_bulk_out);
-        TU_VERIFY(false);
-        return false;
+        case USBTMC_MSGID_VENDOR_SPECIFIC_MSG_OUT:
+        case USBTMC_MSGID_VENDOR_SPECIFIC_IN:
+        default:
+          usbd_edpt_stall(rhport, usbtmc_state.ep_bulk_out);
+          return false;
+        }
+        return true;
       }
-      return true;
-
     case STATE_RCV:
       if(!handle_devMsgOut(rhport, usbtmc_state.ep_bulk_out_buf, xferred_bytes, xferred_bytes))
       {
         usbd_edpt_stall(rhport, usbtmc_state.ep_bulk_out);
-        TU_VERIFY(false);
+        return false;
       }
       return true;
 
     case STATE_ABORTING_BULK_OUT:
-      TU_VERIFY(false);
-      return false; // Should be stalled by now, shouldn't have received a packet.
+      // Should be stalled by now, shouldn't have received a packet.
+      return false;
 
     case STATE_TX_REQUESTED:
     case STATE_TX_INITIATED:
@@ -510,7 +526,7 @@ bool usbtmcd_xfer_cb(uint8_t rhport, uint8_t ep_addr, xfer_result_t result, uint
     case STATE_ABORTING_BULK_IN_SHORTED:
     case STATE_ABORTING_BULK_IN_ABORTED:
     default:
-      TU_VERIFY(false);
+      return false;
     }
   }
   else if(ep_addr == usbtmc_state.ep_bulk_in)
@@ -522,7 +538,7 @@ bool usbtmcd_xfer_cb(uint8_t rhport, uint8_t ep_addr, xfer_result_t result, uint
       break;
 
     case STATE_TX_INITIATED:
-      if(usbtmc_state.transfer_size_remaining >=sizeof(usbtmc_state.ep_bulk_in_buf))
+      if(usbtmc_state.transfer_size_remaining >= sizeof(usbtmc_state.ep_bulk_in_buf))
       {
         // FIXME! This removes const below!
         TU_VERIFY( usbd_edpt_xfer(rhport, usbtmc_state.ep_bulk_in,
@@ -539,7 +555,7 @@ bool usbtmcd_xfer_cb(uint8_t rhport, uint8_t ep_addr, xfer_result_t result, uint
         usbtmc_state.transfer_size_remaining = 0;
         usbtmc_state.devInBuffer = NULL;
         TU_VERIFY( usbd_edpt_xfer(rhport, usbtmc_state.ep_bulk_in, usbtmc_state.ep_bulk_in_buf, (uint16_t)packetLen) );
-        if(((packetLen % USBTMCD_MAX_PACKET_SIZE) != 0) || (packetLen == 0 ))
+        if(((packetLen % usbtmc_state.ep_bulk_in_wMaxPacketSize) != 0) || (packetLen == 0 ))
         {
           usbtmc_state.state = STATE_TX_SHORTED;
         }
@@ -559,7 +575,6 @@ bool usbtmcd_xfer_cb(uint8_t rhport, uint8_t ep_addr, xfer_result_t result, uint
 
     default:
       TU_ASSERT(false);
-      return false;
     }
   }
   else if (ep_addr == usbtmc_state.ep_int_in) {
@@ -589,18 +604,31 @@ bool usbtmcd_control_xfer_cb(uint8_t rhport, uint8_t stage, tusb_control_request
   {
     uint32_t ep_addr = (request->wIndex);
 
+    // At this point, a transfer MAY be in progress. Based on USB spec, when clearing bulk EP HALT,
+    // the EP transfer buffer needs to be cleared and DTOG needs to be reset, even if
+    // the EP is not halted. The only USBD API interface to do this is to stall and then un-stall the EP.
     if(ep_addr == usbtmc_state.ep_bulk_out)
     {
       criticalEnter();
+      usbd_edpt_stall(rhport, (uint8_t)ep_addr);
+      usbd_edpt_clear_stall(rhport, (uint8_t)ep_addr);
       usbtmc_state.state = STATE_NAK; // USBD core has placed EP in NAK state for us
       criticalLeave();
       tud_usbtmc_bulkOut_clearFeature_cb();
     }
     else if (ep_addr == usbtmc_state.ep_bulk_in)
     {
+      usbd_edpt_stall(rhport, (uint8_t)ep_addr);
+      usbd_edpt_clear_stall(rhport, (uint8_t)ep_addr);
       tud_usbtmc_bulkIn_clearFeature_cb();
     }
-    else
+    else if ((usbtmc_state.ep_int_in != 0) && (ep_addr == usbtmc_state.ep_int_in))
+    {
+      // Clearing interrupt in EP
+      usbd_edpt_stall(rhport, (uint8_t)ep_addr);
+      usbd_edpt_clear_stall(rhport, (uint8_t)ep_addr);
+    }
+     else
     {
       return false;
     }
@@ -680,7 +708,7 @@ bool usbtmcd_control_xfer_cb(uint8_t rhport, uint8_t stage, tusb_control_request
     usbtmc_state.transfer_size_remaining = 0u;
       // Check if we've queued a short packet
       criticalEnter();
-      usbtmc_state.state = ((usbtmc_state.transfer_size_sent % USBTMCD_MAX_PACKET_SIZE) == 0) ?
+      usbtmc_state.state = ((usbtmc_state.transfer_size_sent % usbtmc_state.ep_bulk_in_wMaxPacketSize) == 0) ?
               STATE_ABORTING_BULK_IN : STATE_ABORTING_BULK_IN_SHORTED;
       criticalLeave();
       if(usbtmc_state.transfer_size_sent  == 0)
@@ -810,25 +838,32 @@ bool usbtmcd_control_xfer_cb(uint8_t rhport, uint8_t stage, tusb_control_request
 
       bTag = request->wValue & 0x7F;
       TU_VERIFY(request->bmRequestType == 0xA1);
-      TU_VERIFY((request->wValue & (~0x7F)) == 0u); // Other bits are required to be zero
+      TU_VERIFY((request->wValue & (~0x7F)) == 0u); // Other bits are required to be zero (USB488v1.0 Table 11)
       TU_VERIFY(bTag >= 0x02 && bTag <= 127);
       TU_VERIFY(request->wIndex == usbtmc_state.itf_id);
       TU_VERIFY(request->wLength == 0x0003);
       rsp.bTag = (uint8_t)bTag;
       if(usbtmc_state.ep_int_in != 0)
       {
-        rsp.USBTMC_status = USBTMC_STATUS_SUCCESS;
-        rsp.statusByte = 0x00; // Use interrupt endpoint, instead.
-
-        usbtmc_read_stb_interrupt_488_t intMsg =
+        rsp.statusByte = 0x00; // Use interrupt endpoint, instead. Must be 0x00 (USB488v1.0 4.3.1.2)
+        if(usbd_edpt_busy(rhport, usbtmc_state.ep_int_in))
         {
-          .bNotify1 = {
-              .one = 1,
-              .bTag = bTag & 0x7Fu,
-          },
-          .StatusByte = tud_usbtmc_get_stb_cb(&(rsp.USBTMC_status))
-        };
-        usbd_edpt_xfer(rhport, usbtmc_state.ep_int_in, (void*)&intMsg, sizeof(intMsg));
+          rsp.USBTMC_status = USB488_STATUS_INTERRUPT_IN_BUSY;
+        }
+        else
+        {
+          rsp.USBTMC_status = USBTMC_STATUS_SUCCESS;
+          usbtmc_read_stb_interrupt_488_t intMsg =
+          {
+            .bNotify1 = {
+                .one = 1,
+                .bTag = bTag & 0x7Fu,
+            },
+            .StatusByte = tud_usbtmc_get_stb_cb(&(rsp.USBTMC_status))
+          };
+          // Must be queued before control request response sent (USB488v1.0 4.3.1.2)
+          usbd_edpt_xfer(rhport, usbtmc_state.ep_int_in, (void*)&intMsg, sizeof(intMsg));
+        }
       }
       else
       {
@@ -843,16 +878,13 @@ bool usbtmcd_control_xfer_cb(uint8_t rhport, uint8_t stage, tusb_control_request
   case USB488_bREQUEST_LOCAL_LOCKOUT:
     {
       TU_VERIFY(request->bmRequestType == 0xA1); // in,class,interface
-      TU_VERIFY(false);
       return false;
     }
 #endif
 
   default:
-    TU_VERIFY(false);
     return false;
   }
-  TU_VERIFY(false);
 }
 
 #endif /* CFG_TUD_TSMC */
diff --git a/src/class/usbtmc/usbtmc_device.h b/src/class/usbtmc/usbtmc_device.h
index 0549a1569..c1298ddb8 100644
--- a/src/class/usbtmc/usbtmc_device.h
+++ b/src/class/usbtmc/usbtmc_device.h
@@ -35,12 +35,8 @@
 #define CFG_TUD_USBTMC_ENABLE_488 (1)
 #endif
 
-// USB spec says that full-speed must be 8,16,32, or 64.
-// However, this driver implementation requires it to be >=32
-#define USBTMCD_MAX_PACKET_SIZE (64u)
-
 /***********************************************
- *  Functions to be implemeted by the class implementation
+ *  Functions to be implemented by the class implementation
  */
 
 // In order to proceed, app must call call tud_usbtmc_start_bus_read(rhport) during or soon after:
diff --git a/src/class/vendor/vendor_device.c b/src/class/vendor/vendor_device.c
index 6e3ceb1c4..d07bd75ec 100644
--- a/src/class/vendor/vendor_device.c
+++ b/src/class/vendor/vendor_device.c
@@ -59,7 +59,7 @@ typedef struct
   CFG_TUSB_MEM_ALIGN uint8_t epin_buf[CFG_TUD_VENDOR_EPSIZE];
 } vendord_interface_t;
 
-CFG_TUSB_MEM_SECTION static vendord_interface_t _vendord_itf[CFG_TUD_VENDOR];
+CFG_TUSB_MEM_SECTION tu_static vendord_interface_t _vendord_itf[CFG_TUD_VENDOR];
 
 #define ITF_MEM_RESET_SIZE   offsetof(vendord_interface_t, rx_ff)
 
@@ -84,21 +84,23 @@ bool tud_vendor_n_peek(uint8_t itf, uint8_t* u8)
 //--------------------------------------------------------------------+
 static void _prep_out_transaction (vendord_interface_t* p_itf)
 {
+  uint8_t const rhport = 0;
+
   // skip if previous transfer not complete
-  if ( usbd_edpt_busy(TUD_OPT_RHPORT, p_itf->ep_out) ) return;
+  if ( usbd_edpt_busy(rhport, p_itf->ep_out) ) return;
 
   // Prepare for incoming data but only allow what we can store in the ring buffer.
   uint16_t max_read = tu_fifo_remaining(&p_itf->rx_ff);
   if ( max_read >= CFG_TUD_VENDOR_EPSIZE )
   {
-    usbd_edpt_xfer(TUD_OPT_RHPORT, p_itf->ep_out, p_itf->epout_buf, CFG_TUD_VENDOR_EPSIZE);
+    usbd_edpt_xfer(rhport, p_itf->ep_out, p_itf->epout_buf, CFG_TUD_VENDOR_EPSIZE);
   }
 }
 
 uint32_t tud_vendor_n_read (uint8_t itf, void* buffer, uint32_t bufsize)
 {
   vendord_interface_t* p_itf = &_vendord_itf[itf];
-  uint32_t num_read = tu_fifo_read_n(&p_itf->rx_ff, buffer, bufsize);
+  uint32_t num_read = tu_fifo_read_n(&p_itf->rx_ff, buffer, (uint16_t) bufsize);
   _prep_out_transaction(p_itf);
   return num_read;
 }
@@ -115,13 +117,15 @@ void tud_vendor_n_read_flush (uint8_t itf)
 //--------------------------------------------------------------------+
 static uint16_t maybe_transmit(vendord_interface_t* p_itf)
 {
+  uint8_t const rhport = 0;
+
   // skip if previous transfer not complete
-  TU_VERIFY( !usbd_edpt_busy(TUD_OPT_RHPORT, p_itf->ep_in) );
+  TU_VERIFY( !usbd_edpt_busy(rhport, p_itf->ep_in) );
 
   uint16_t count = tu_fifo_read_n(&p_itf->tx_ff, p_itf->epin_buf, CFG_TUD_VENDOR_EPSIZE);
   if (count > 0)
   {
-    TU_ASSERT( usbd_edpt_xfer(TUD_OPT_RHPORT, p_itf->ep_in, p_itf->epin_buf, count) );
+    TU_ASSERT( usbd_edpt_xfer(rhport, p_itf->ep_in, p_itf->epin_buf, count) );
   }
   return count;
 }
@@ -129,7 +133,7 @@ static uint16_t maybe_transmit(vendord_interface_t* p_itf)
 uint32_t tud_vendor_n_write (uint8_t itf, void const* buffer, uint32_t bufsize)
 {
   vendord_interface_t* p_itf = &_vendord_itf[itf];
-  uint16_t ret = tu_fifo_write_n(&p_itf->tx_ff, buffer, bufsize);
+  uint16_t ret = tu_fifo_write_n(&p_itf->tx_ff, buffer, (uint16_t) bufsize);
   if (tu_fifo_count(&p_itf->tx_ff) >= CFG_TUD_VENDOR_EPSIZE) {
     maybe_transmit(p_itf);
   }
@@ -227,7 +231,7 @@ uint16_t vendord_open(uint8_t rhport, tusb_desc_interface_t const * desc_itf, ui
     if ( p_vendor->ep_in ) maybe_transmit(p_vendor);
   }
 
-  return (uintptr_t) p_desc - (uintptr_t) desc_itf;
+  return (uint16_t) ((uintptr_t) p_desc - (uintptr_t) desc_itf);
 }
 
 bool vendord_xfer_cb(uint8_t rhport, uint8_t ep_addr, xfer_result_t result, uint32_t xferred_bytes)
@@ -248,7 +252,7 @@ bool vendord_xfer_cb(uint8_t rhport, uint8_t ep_addr, xfer_result_t result, uint
   if ( ep_addr == p_itf->ep_out )
   {
     // Receive new data
-    tu_fifo_write_n(&p_itf->rx_ff, p_itf->epout_buf, xferred_bytes);
+    tu_fifo_write_n(&p_itf->rx_ff, p_itf->epout_buf, (uint16_t) xferred_bytes);
 
     // Invoked callback if any
     if (tud_vendor_rx_cb) tud_vendor_rx_cb(itf);
@@ -257,7 +261,7 @@ bool vendord_xfer_cb(uint8_t rhport, uint8_t ep_addr, xfer_result_t result, uint
   }
   else if ( ep_addr == p_itf->ep_in )
   {
-    if (tud_vendor_tx_cb) tud_vendor_tx_cb(itf, xferred_bytes);
+    if (tud_vendor_tx_cb) tud_vendor_tx_cb(itf, (uint16_t) xferred_bytes);
     // Send complete, try to send more if possible
     maybe_transmit(p_itf);
   }
diff --git a/src/class/vendor/vendor_device.h b/src/class/vendor/vendor_device.h
index 4a873e5fc..9abafda50 100644
--- a/src/class/vendor/vendor_device.h
+++ b/src/class/vendor/vendor_device.h
@@ -1,4 +1,4 @@
-/* 
+/*
  * The MIT License (MIT)
  *
  * Copyright (c) 2019 Ha Thach (tinyusb.org)
@@ -50,8 +50,7 @@ void     tud_vendor_n_read_flush      (uint8_t itf);
 uint32_t tud_vendor_n_write           (uint8_t itf, void const* buffer, uint32_t bufsize);
 uint32_t tud_vendor_n_write_available (uint8_t itf);
 
-static inline
-uint32_t tud_vendor_n_write_str       (uint8_t itf, char const* str);
+static inline uint32_t tud_vendor_n_write_str (uint8_t itf, char const* str);
 uint32_t tud_vendor_n_flush           (uint8_t itf);
 
 //--------------------------------------------------------------------+
diff --git a/src/class/vendor/vendor_host.c b/src/class/vendor/vendor_host.c
index dbea1228d..e66c5007f 100644
--- a/src/class/vendor/vendor_host.c
+++ b/src/class/vendor/vendor_host.c
@@ -1,4 +1,4 @@
-/* 
+/*
  * The MIT License (MIT)
  *
  * Copyright (c) 2019 Ha Thach (tinyusb.org)
diff --git a/src/class/vendor/vendor_host.h b/src/class/vendor/vendor_host.h
index 65223fbca..acfebe7a4 100644
--- a/src/class/vendor/vendor_host.h
+++ b/src/class/vendor/vendor_host.h
@@ -1,4 +1,4 @@
-/* 
+/*
  * The MIT License (MIT)
  *
  * Copyright (c) 2019 Ha Thach (tinyusb.org)
diff --git a/src/class/video/video.h b/src/class/video/video.h
index 844746546..c0088c4f6 100644
--- a/src/class/video/video.h
+++ b/src/class/video/video.h
@@ -303,6 +303,45 @@ typedef struct TU_ATTR_PACKED {
 } tusb_desc_cs_video_fmt_uncompressed_t;
 
 typedef struct TU_ATTR_PACKED {
+  uint8_t bLength;
+  uint8_t bDescriptorType;
+  uint8_t bDescriptorSubType;
+  uint8_t bFormatIndex;
+  uint8_t bNumFrameDescriptors;
+  uint8_t bmFlags;
+  uint8_t bDefaultFrameIndex;
+  uint8_t bAspectRatioX;
+  uint8_t bAspectRatioY;
+  uint8_t bmInterlaceFlags;
+  uint8_t bCopyProtect;
+} tusb_desc_cs_video_fmt_mjpeg_t;
+
+typedef struct TU_ATTR_PACKED {
+  uint8_t  bLength;
+  uint8_t  bDescriptorType;
+  uint8_t  bDescriptorSubType;
+  uint8_t  bFormatIndex;
+  uint32_t dwMaxVideoFrameBufferSize; /* deprecated */
+  uint8_t  bFormatType;
+} tusb_desc_cs_video_fmt_dv_t;
+
+typedef struct TU_ATTR_PACKED {
+  uint8_t bLength;
+  uint8_t bDescriptorType;
+  uint8_t bDescriptorSubType;
+  uint8_t bFormatIndex;
+  uint8_t bNumFrameDescriptors;
+  uint8_t guidFormat[16];
+  uint8_t bBitsPerPixel;
+  uint8_t bDefaultFrameIndex;
+  uint8_t bAspectRatioX;
+  uint8_t bAspectRatioY;
+  uint8_t bmInterlaceFlags;
+  uint8_t bCopyProtect;
+  uint8_t bVaribaleSize;
+} tusb_desc_cs_video_fmt_frame_based_t;
+
+typedef struct TU_ATTR_PACKED {
   uint8_t  bLength;
   uint8_t  bDescriptorType;
   uint8_t  bDescriptorSubType;
@@ -318,6 +357,24 @@ typedef struct TU_ATTR_PACKED {
   uint32_t dwFrameInterval[];
 } tusb_desc_cs_video_frm_uncompressed_t;
 
+typedef tusb_desc_cs_video_frm_uncompressed_t tusb_desc_cs_video_frm_mjpeg_t;
+
+typedef struct TU_ATTR_PACKED {
+  uint8_t  bLength;
+  uint8_t  bDescriptorType;
+  uint8_t  bDescriptorSubType;
+  uint8_t  bFrameIndex;
+  uint8_t  bmCapabilities;
+  uint16_t wWidth;
+  uint16_t wHeight;
+  uint32_t dwMinBitRate;
+  uint32_t dwMaxBitRate;
+  uint32_t dwDefaultFrameInterval;
+  uint8_t  bFrameIntervalType;
+  uint32_t dwBytesPerLine;
+  uint32_t dwFrameInterval[];
+} tusb_desc_cs_video_frm_frame_based_t;
+
 //--------------------------------------------------------------------+
 // Requests
 //--------------------------------------------------------------------+
@@ -378,8 +435,11 @@ TU_VERIFY_STATIC( sizeof(video_probe_and_commit_control_t) == 48, "size is not c
 #define TUD_VIDEO_DESC_CS_VS_IN_LEN               13
 #define TUD_VIDEO_DESC_CS_VS_OUT_LEN              9
 #define TUD_VIDEO_DESC_CS_VS_FMT_UNCOMPR_LEN      27
+#define TUD_VIDEO_DESC_CS_VS_FMT_MJPEG_LEN        11
 #define TUD_VIDEO_DESC_CS_VS_FRM_UNCOMPR_CONT_LEN 38
 #define TUD_VIDEO_DESC_CS_VS_FRM_UNCOMPR_DISC_LEN 26
+#define TUD_VIDEO_DESC_CS_VS_FRM_MJPEG_CONT_LEN   38
+#define TUD_VIDEO_DESC_CS_VS_FRM_MJPEG_DISC_LEN   26
 #define TUD_VIDEO_DESC_CS_VS_COLOR_MATCHING_LEN   6
 
 /* 2.2 compression formats */
@@ -462,6 +522,25 @@ TU_VERIFY_STATIC( sizeof(video_probe_and_commit_control_t) == 48, "size is not c
   _frmidx, _cap, U16_TO_U8S_LE(_width), U16_TO_U8S_LE(_height), U32_TO_U8S_LE(_minbr), U32_TO_U8S_LE(_maxbr), \
   U32_TO_U8S_LE(_maxfrmbufsz), U32_TO_U8S_LE(_frminterval), (TU_ARGS_NUM(__VA_ARGS__)), __VA_ARGS__
 
+/* Motion-JPEG 3.1.1 Table 3-1 */
+#define TUD_VIDEO_DESC_CS_VS_FMT_MJPEG(_fmtidx, _numfrmdesc, _fixed_sz, _frmidx, _asrx, _asry, _interlace, _cp) \
+  TUD_VIDEO_DESC_CS_VS_FMT_MJPEG_LEN, TUSB_DESC_CS_INTERFACE, VIDEO_CS_ITF_VS_FORMAT_MJPEG, \
+  _fmtidx, _numfrmdesc, _fixed_sz, _frmidx, _asrx,  _asry, _interlace, _cp
+
+/* Motion-JPEG 3.1.1 Table 3-2 and 3-3 */
+#define TUD_VIDEO_DESC_CS_VS_FRM_MJPEG_CONT(_frmidx, _cap, _width, _height, _minbr, _maxbr, _maxfrmbufsz, _frminterval, _minfrminterval, _maxfrminterval, _frmintervalstep) \
+  TUD_VIDEO_DESC_CS_VS_FRM_MJPEG_CONT_LEN, TUSB_DESC_CS_INTERFACE, VIDEO_CS_ITF_VS_FRAME_MJPEG, \
+  _frmidx, _cap, U16_TO_U8S_LE(_width), U16_TO_U8S_LE(_height), U32_TO_U8S_LE(_minbr), U32_TO_U8S_LE(_maxbr), \
+  U32_TO_U8S_LE(_maxfrmbufsz), U32_TO_U8S_LE(_frminterval), 0, \
+  U32_TO_U8S_LE(_minfrminterval), U32_TO_U8S_LE(_maxfrminterval), U32_TO_U8S_LE(_frmintervalstep)
+
+/* Motion-JPEG 3.1.1 Table 3-2 and 3-4 */
+#define TUD_VIDEO_DESC_CS_VS_FRM_MJPEG_DISC(_frmidx, _cap, _width, _height, _minbr, _maxbr, _maxfrmbufsz, _frminterval, ...) \
+  TUD_VIDEO_DESC_CS_VS_FRM_MJPEG_DISC_LEN + (TU_ARGS_NUM(__VA_ARGS__)) * 4, \
+  TUSB_DESC_CS_INTERFACE, VIDEO_CS_VS_INTERFACE_FRAME_MJPEG, \
+  _frmidx, _cap, U16_TO_U8S_LE(_width), U16_TO_U8S_LE(_height), U32_TO_U8S_LE(_minbr), U32_TO_U8S_LE(_maxbr), \
+  U32_TO_U8S_LE(_maxfrmbufsz), U32_TO_U8S_LE(_frminterval), (TU_ARGS_NUM(__VA_ARGS__)), __VA_ARGS__
+
 /* 3.9.2.6 */
 #define TUD_VIDEO_DESC_CS_VS_COLOR_MATCHING(_color, _trns, _mat) \
   TUD_VIDEO_DESC_CS_VS_COLOR_MATCHING_LEN, \
@@ -470,7 +549,7 @@ TU_VERIFY_STATIC( sizeof(video_probe_and_commit_control_t) == 48, "size is not c
 
 /* 3.10.1.1 */
 #define TUD_VIDEO_DESC_EP_ISO(_ep, _epsize, _ep_interval) \
-  7, TUSB_DESC_ENDPOINT, _ep, TUSB_XFER_ISOCHRONOUS | TUSB_ISO_EP_ATT_ASYNCHRONOUS,\
+  7, TUSB_DESC_ENDPOINT, _ep, (uint8_t) (TUSB_XFER_ISOCHRONOUS | TUSB_ISO_EP_ATT_ASYNCHRONOUS),\
   U16_TO_U8S_LE(_epsize), _ep_interval
 
 /* 3.10.1.2 */
diff --git a/src/class/video/video_device.c b/src/class/video/video_device.c
index 91718f205..d6e98602b 100644
--- a/src/class/video/video_device.c
+++ b/src/class/video/video_device.c
@@ -1,4 +1,4 @@
-/* 
+/*
  * The MIT License (MIT)
  *
  * Copyright (c) 2021 Koji KITAYAMA
@@ -59,6 +59,34 @@ typedef struct TU_ATTR_PACKED {
   uint8_t bEntityId;
 } tusb_desc_cs_video_entity_itf_t;
 
+typedef union {
+  struct TU_ATTR_PACKED {
+    uint8_t bLength;
+    uint8_t bDescriptorType;
+    uint8_t bDescriptorSubType;
+    uint8_t bFormatIndex;
+    uint8_t bNumFrameDescriptors;
+  };
+  tusb_desc_cs_video_fmt_uncompressed_t uncompressed;
+  tusb_desc_cs_video_fmt_mjpeg_t        mjpeg;
+  tusb_desc_cs_video_fmt_frame_based_t  frame_based;
+} tusb_desc_cs_video_fmt_t;
+
+typedef union {
+  struct TU_ATTR_PACKED {
+    uint8_t  bLength;
+    uint8_t  bDescriptorType;
+    uint8_t  bDescriptorSubType;
+    uint8_t  bFrameIndex;
+    uint8_t  bmCapabilities;
+    uint16_t wWidth;
+    uint16_t wHeight;
+  };
+  tusb_desc_cs_video_frm_uncompressed_t uncompressed;
+  tusb_desc_cs_video_frm_mjpeg_t        mjpeg;
+  tusb_desc_cs_video_frm_frame_based_t  frame_based;
+} tusb_desc_cs_video_frm_t;
+
 /* video streaming interface */
 typedef struct TU_ATTR_PACKED {
   uint8_t index_vc;  /* index of bound video control interface */
@@ -80,7 +108,7 @@ typedef struct TU_ATTR_PACKED {
 
 /* video control interface */
 typedef struct TU_ATTR_PACKED {
-  void const *beg;  /* The head of the first video control interface descriptor */
+  uint8_t const *beg;  /* The head of the first video control interface descriptor */
   uint16_t    len;  /* Byte length of the descriptors */
   uint16_t    cur;  /* offset for current video control interface */
   uint8_t     stm[CFG_TUD_VIDEO_STREAMING]; /* Indices of streaming interface */
@@ -97,11 +125,11 @@ typedef struct TU_ATTR_PACKED {
 //--------------------------------------------------------------------+
 // INTERNAL OBJECT & FUNCTION DECLARATION
 //--------------------------------------------------------------------+
-CFG_TUSB_MEM_SECTION static videod_interface_t _videod_itf[CFG_TUD_VIDEO];
-CFG_TUSB_MEM_SECTION static videod_streaming_interface_t _videod_streaming_itf[CFG_TUD_VIDEO_STREAMING];
+CFG_TUSB_MEM_SECTION tu_static videod_interface_t _videod_itf[CFG_TUD_VIDEO];
+CFG_TUSB_MEM_SECTION tu_static videod_streaming_interface_t _videod_streaming_itf[CFG_TUD_VIDEO_STREAMING];
 
-static uint8_t const _cap_get     = 0x1u; /* support for GET */
-static uint8_t const _cap_get_set = 0x3u; /* support for GET and SET */
+tu_static uint8_t const _cap_get     = 0x1u; /* support for GET */
+tu_static uint8_t const _cap_get_set = 0x3u; /* support for GET and SET */
 
 /** Get interface number from the interface descriptor
  *
@@ -146,7 +174,7 @@ static tusb_desc_vc_itf_t const* _get_desc_vc(videod_interface_t const *self)
 static tusb_desc_vs_itf_t const* _get_desc_vs(videod_streaming_interface_t const *self)
 {
   if (!self->desc.cur) return NULL;
-  void const *desc = _videod_itf[self->index_vc].beg;
+  uint8_t const *desc = _videod_itf[self->index_vc].beg;
   return (tusb_desc_vs_itf_t const*)(desc + self->desc.cur);
 }
 
@@ -219,9 +247,9 @@ static void const* _next_desc_itf(void const *beg, void const *end)
  *
  * @return The pointer for interface descriptor.
  * @retval end   did not found interface descriptor */
-static inline void const* _find_desc_itf(void const *beg, void const *end, uint_fast8_t itfnum, uint_fast8_t altnum)
+static inline uint8_t const* _find_desc_itf(void const *beg, void const *end, uint_fast8_t itfnum, uint_fast8_t altnum)
 {
-  return _find_desc_3(beg, end, TUSB_DESC_INTERFACE, itfnum, altnum);
+  return (uint8_t const*) _find_desc_3(beg, end, TUSB_DESC_INTERFACE, itfnum, altnum);
 }
 
 /** Find the first endpoint descriptor belonging to the current interface descriptor.
@@ -243,6 +271,13 @@ static void const* _find_desc_ep(void const *beg, void const *end)
   return end;
 }
 
+/** Return the end of the video control descriptor. */
+static inline void const* _end_of_control_descriptor(void const *desc)
+{
+  tusb_desc_vc_itf_t const *vc = (tusb_desc_vc_itf_t const *)desc;
+  return ((uint8_t const*) desc) + vc->std.bLength + tu_le16toh(vc->ctl.wTotalLength);
+}
+
 /** Find the first entity descriptor with the entity ID
  *  specified by the argument belonging to the current video control descriptor.
  *
@@ -253,10 +288,8 @@ static void const* _find_desc_ep(void const *beg, void const *end)
  * @retval end   did not found interface descriptor */
 static void const* _find_desc_entity(void const *desc, uint_fast8_t entityid)
 {
-  tusb_desc_vc_itf_t const *vc = (tusb_desc_vc_itf_t const*)desc;
-  void const *beg = vc;
-  void const *end = beg + vc->std.bLength + vc->ctl.wTotalLength;
-  for (void const *cur = beg; cur < end; cur = _find_desc(cur, end, TUSB_DESC_CS_INTERFACE)) {
+  void const *end = _end_of_control_descriptor(desc);
+  for (void const *cur = desc; cur < end; cur = _find_desc(cur, end, TUSB_DESC_CS_INTERFACE)) {
     tusb_desc_cs_video_entity_itf_t const *itf = (tusb_desc_cs_video_entity_itf_t const *)cur;
     if ((VIDEO_CS_ITF_VC_INPUT_TERMINAL  <= itf->bDescriptorSubtype
          && itf->bDescriptorSubtype < VIDEO_CS_ITF_VC_MAX)
@@ -272,21 +305,42 @@ static void const* _find_desc_entity(void const *desc, uint_fast8_t entityid)
 static inline void const* _end_of_streaming_descriptor(void const *desc)
 {
   tusb_desc_vs_itf_t const *vs = (tusb_desc_vs_itf_t const *)desc;
-  return desc + vs->std.bLength + vs->stm.wTotalLength;
+  return ((uint8_t const*) desc) + vs->std.bLength + tu_le16toh(vs->stm.wTotalLength);
 }
 
 /** Find the first format descriptor with the specified format number. */
-static inline tusb_desc_cs_video_fmt_uncompressed_t const *_find_desc_format(void const *beg, void const *end, uint_fast8_t fmtnum)
+static inline void const *_find_desc_format(void const *beg, void const *end, uint_fast8_t fmtnum)
 {
-  return (tusb_desc_cs_video_fmt_uncompressed_t const*)
-    _find_desc_3(beg, end, TUSB_DESC_CS_INTERFACE, VIDEO_CS_ITF_VS_FORMAT_UNCOMPRESSED, fmtnum);
+  for (void const *cur = beg; cur < end; cur = _find_desc(cur, end, TUSB_DESC_CS_INTERFACE)) {
+    uint8_t const *p = (uint8_t const *)cur;
+    uint_fast8_t fmt = p[2];
+    if ((fmt == VIDEO_CS_ITF_VS_FORMAT_UNCOMPRESSED ||
+         fmt == VIDEO_CS_ITF_VS_FORMAT_MJPEG ||
+         fmt == VIDEO_CS_ITF_VS_FORMAT_DV ||
+         fmt == VIDEO_CS_ITF_VS_FRAME_FRAME_BASED) &&
+        fmtnum == p[3]) {
+      return cur;
+    }
+    cur = tu_desc_next(cur);
+  }
+  return end;
 }
 
 /** Find the first frame descriptor with the specified format number. */
-static inline tusb_desc_cs_video_frm_uncompressed_t const *_find_desc_frame(void const *beg, void const *end, uint_fast8_t frmnum)
+static inline void const *_find_desc_frame(void const *beg, void const *end, uint_fast8_t frmnum)
 {
-  return (tusb_desc_cs_video_frm_uncompressed_t const*)
-    _find_desc_3(beg, end, TUSB_DESC_CS_INTERFACE, VIDEO_CS_ITF_VS_FRAME_UNCOMPRESSED, frmnum);
+  for (void const *cur = beg; cur < end; cur = _find_desc(cur, end, TUSB_DESC_CS_INTERFACE)) {
+    uint8_t const *p = (uint8_t const *)cur;
+    uint_fast8_t frm = p[2];
+    if ((frm == VIDEO_CS_ITF_VS_FRAME_UNCOMPRESSED ||
+         frm == VIDEO_CS_ITF_VS_FRAME_MJPEG ||
+         frm == VIDEO_CS_ITF_VS_FRAME_FRAME_BASED) &&
+        frmnum == p[3]) {
+      return cur;
+    }
+    cur = tu_desc_next(cur);
+  }
+  return end;
 }
 
 /** Set uniquely determined values to variables that have not been set
@@ -297,7 +351,7 @@ static bool _update_streaming_parameters(videod_streaming_interface_t const *stm
 {
   tusb_desc_vs_itf_t const *vs = _get_desc_vs(stm);
   uint_fast8_t fmtnum = param->bFormatIndex;
-  TU_ASSERT(fmtnum <= vs->stm.bNumFormats);
+  TU_ASSERT(vs && fmtnum <= vs->stm.bNumFormats);
   if (!fmtnum) {
     if (1 < vs->stm.bNumFormats) return true; /* Need to negotiate all variables. */
     fmtnum = 1;
@@ -307,7 +361,6 @@ static bool _update_streaming_parameters(videod_streaming_interface_t const *stm
   /* Set the parameters determined by the format  */
   param->wKeyFrameRate    = 1;
   param->wPFrameRate      = 0;
-  param->wCompQuality     = 1; /* 1 to 10000 */
   param->wCompWindowSize  = 1; /* GOP size? */
   param->wDelay           = 0; /* milliseconds */
   param->dwClockFrequency = 27000000; /* same as MPEG-2 system time clock  */
@@ -319,8 +372,18 @@ static bool _update_streaming_parameters(videod_streaming_interface_t const *stm
   param->bBitDepthLuma    = 8;
 
   void const *end = _end_of_streaming_descriptor(vs);
-  tusb_desc_cs_video_fmt_uncompressed_t const *fmt = _find_desc_format(tu_desc_next(vs), end, fmtnum);
+  tusb_desc_cs_video_fmt_t const *fmt = _find_desc_format(tu_desc_next(vs), end, fmtnum);
   TU_ASSERT(fmt != end);
+
+  switch (fmt->bDescriptorSubType) {
+    case VIDEO_CS_ITF_VS_FORMAT_UNCOMPRESSED:
+      param->wCompQuality = 1; /* 1 to 10000 */
+      break;
+  case VIDEO_CS_ITF_VS_FORMAT_MJPEG:
+      break;
+    default: return false;
+  }
+
   uint_fast8_t frmnum = param->bFrameIndex;
   TU_ASSERT(frmnum <= fmt->bNumFrameDescriptors);
   if (!frmnum) {
@@ -328,28 +391,39 @@ static bool _update_streaming_parameters(videod_streaming_interface_t const *stm
     frmnum = 1;
     param->bFrameIndex = 1;
   }
-  tusb_desc_cs_video_frm_uncompressed_t const *frm = _find_desc_frame(tu_desc_next(fmt), end, frmnum);
+  tusb_desc_cs_video_frm_t const *frm = _find_desc_frame(tu_desc_next(fmt), end, frmnum);
   TU_ASSERT(frm != end);
 
   /* Set the parameters determined by the frame  */
   uint_fast32_t frame_size = param->dwMaxVideoFrameSize;
   if (!frame_size) {
-    frame_size = (uint_fast32_t)frm->wWidth * frm->wHeight * fmt->bBitsPerPixel / 8;
+    switch (fmt->bDescriptorSubType) {
+      case VIDEO_CS_ITF_VS_FORMAT_UNCOMPRESSED:
+        frame_size = (uint_fast32_t)frm->wWidth * frm->wHeight * fmt->uncompressed.bBitsPerPixel / 8;
+        break;
+      case VIDEO_CS_ITF_VS_FORMAT_MJPEG:
+        frame_size = (uint_fast32_t)frm->wWidth * frm->wHeight * 16 / 8; /* YUV422 */
+        break;
+      default: break;
+    }
     param->dwMaxVideoFrameSize = frame_size;
   }
 
   uint_fast32_t interval = param->dwFrameInterval;
   if (!interval) {
-    if ((1 < frm->bFrameIntervalType) ||
-        ((0 == frm->bFrameIntervalType) && (frm->dwFrameInterval[1] != frm->dwFrameInterval[0]))) {
+    if ((1 < frm->uncompressed.bFrameIntervalType) ||
+        ((0 == frm->uncompressed.bFrameIntervalType) &&
+         (frm->uncompressed.dwFrameInterval[1] != frm->uncompressed.dwFrameInterval[0]))) {
       return true;
     }
-    interval = frm->dwFrameInterval[0];
+    interval = frm->uncompressed.dwFrameInterval[0];
     param->dwFrameInterval = interval;
   }
   uint_fast32_t interval_ms = interval / 10000;
   TU_ASSERT(interval_ms);
   uint_fast32_t payload_size = (frame_size + interval_ms - 1) / interval_ms + 2;
+  if (CFG_TUD_VIDEO_STREAMING_EP_BUFSIZE < payload_size)
+    payload_size = CFG_TUD_VIDEO_STREAMING_EP_BUFSIZE;
   param->dwMaxPayloadTransferSize = payload_size;
   return true;
 }
@@ -366,7 +440,8 @@ static bool _negotiate_streaming_parameters(videod_streaming_interface_t const *
   if (!fmtnum) {
     switch (request) {
       case VIDEO_REQUEST_GET_MAX:
-        param->bFormatIndex = _get_desc_vs(stm)->stm.bNumFormats;
+        if (_get_desc_vs(stm))
+          param->bFormatIndex = _get_desc_vs(stm)->stm.bNumFormats;
         break;
       case VIDEO_REQUEST_GET_MIN:
       case VIDEO_REQUEST_GET_DEF:
@@ -393,8 +468,9 @@ static bool _negotiate_streaming_parameters(videod_streaming_interface_t const *
   uint_fast8_t frmnum = param->bFrameIndex;
   if (!frmnum) {
     tusb_desc_vs_itf_t const *vs = _get_desc_vs(stm);
+    TU_ASSERT(vs);
     void const *end = _end_of_streaming_descriptor(vs);
-    tusb_desc_cs_video_fmt_uncompressed_t const *fmt = _find_desc_format(tu_desc_next(vs), end, fmtnum);
+    tusb_desc_cs_video_fmt_t const *fmt = _find_desc_format(tu_desc_next(vs), end, fmtnum);
     switch (request) {
       case VIDEO_REQUEST_GET_MAX:
         frmnum = fmt->bNumFrameDescriptors;
@@ -403,31 +479,50 @@ static bool _negotiate_streaming_parameters(videod_streaming_interface_t const *
         frmnum = 1;
         break;
       case VIDEO_REQUEST_GET_DEF:
-        frmnum = fmt->bDefaultFrameIndex;
+        switch (fmt->bDescriptorSubType) {
+        case VIDEO_CS_ITF_VS_FORMAT_UNCOMPRESSED:
+          frmnum = fmt->uncompressed.bDefaultFrameIndex;
+          break;
+        case VIDEO_CS_ITF_VS_FORMAT_MJPEG:
+          frmnum = fmt->mjpeg.bDefaultFrameIndex;
+          break;
+        default: return false;
+        }
         break;
       default: return false;
     }
-    param->bFrameIndex = frmnum;
+    param->bFrameIndex = (uint8_t)frmnum;
     /* Set the parameters determined by the frame */
-    tusb_desc_cs_video_frm_uncompressed_t const *frm = _find_desc_frame(tu_desc_next(fmt), end, frmnum);
-    param->dwMaxVideoFrameSize = frm->wWidth * frm->wHeight * fmt->bBitsPerPixel / 8;
+    tusb_desc_cs_video_frm_t const *frm = _find_desc_frame(tu_desc_next(fmt), end, frmnum);
+    uint_fast32_t frame_size;
+    switch (fmt->bDescriptorSubType) {
+      case VIDEO_CS_ITF_VS_FORMAT_UNCOMPRESSED:
+        frame_size = (uint_fast32_t)frm->wWidth * frm->wHeight * fmt->uncompressed.bBitsPerPixel / 8;
+        break;
+      case VIDEO_CS_ITF_VS_FORMAT_MJPEG:
+        frame_size = (uint_fast32_t)frm->wWidth * frm->wHeight * 16 / 8; /* YUV422 */
+        break;
+      default: return false;
+    }
+    param->dwMaxVideoFrameSize = frame_size;
     return true;
   }
 
   if (!param->dwFrameInterval) {
     tusb_desc_vs_itf_t const *vs = _get_desc_vs(stm);
+    TU_ASSERT(vs);
     void const *end = _end_of_streaming_descriptor(vs);
-    tusb_desc_cs_video_fmt_uncompressed_t const *fmt = _find_desc_format(tu_desc_next(vs), end, fmtnum);
-    tusb_desc_cs_video_frm_uncompressed_t const *frm = _find_desc_frame(tu_desc_next(fmt), end, frmnum);
+    tusb_desc_cs_video_fmt_t const *fmt = _find_desc_format(tu_desc_next(vs), end, fmtnum);
+    tusb_desc_cs_video_frm_t const *frm = _find_desc_frame(tu_desc_next(fmt), end, frmnum);
 
     uint_fast32_t interval, interval_ms;
     switch (request) {
       case VIDEO_REQUEST_GET_MAX:
         {
           uint_fast32_t min_interval, max_interval;
-          uint_fast8_t num_intervals = frm->bFrameIntervalType;
-          max_interval = num_intervals ? frm->dwFrameInterval[num_intervals - 1]: frm->dwFrameInterval[1];
-          min_interval = frm->dwFrameInterval[0];
+          uint_fast8_t num_intervals = frm->uncompressed.bFrameIntervalType;
+          max_interval = num_intervals ? frm->uncompressed.dwFrameInterval[num_intervals - 1]: frm->uncompressed.dwFrameInterval[1];
+          min_interval = frm->uncompressed.dwFrameInterval[0];
           interval = max_interval;
           interval_ms = min_interval / 10000;
         }
@@ -435,24 +530,24 @@ static bool _negotiate_streaming_parameters(videod_streaming_interface_t const *
       case VIDEO_REQUEST_GET_MIN:
         {
           uint_fast32_t min_interval, max_interval;
-          uint_fast8_t num_intervals = frm->bFrameIntervalType;
-          max_interval = num_intervals ? frm->dwFrameInterval[num_intervals - 1]: frm->dwFrameInterval[1];
-          min_interval = frm->dwFrameInterval[0];
+          uint_fast8_t num_intervals = frm->uncompressed.bFrameIntervalType;
+          max_interval = num_intervals ? frm->uncompressed.dwFrameInterval[num_intervals - 1]: frm->uncompressed.dwFrameInterval[1];
+          min_interval = frm->uncompressed.dwFrameInterval[0];
           interval = min_interval;
           interval_ms = max_interval / 10000;
         }
         break;
       case VIDEO_REQUEST_GET_DEF:
-        interval = frm->dwDefaultFrameInterval;
+        interval = frm->uncompressed.dwDefaultFrameInterval;
         interval_ms = interval / 10000;
         break;
       case VIDEO_REQUEST_GET_RES:
         {
-          uint_fast8_t num_intervals = frm->bFrameIntervalType;
+          uint_fast8_t num_intervals = frm->uncompressed.bFrameIntervalType;
           if (num_intervals) {
             interval = 0;
           } else {
-            interval = frm->dwFrameInterval[2];
+            interval = frm->uncompressed.dwFrameInterval[2];
             interval_ms = interval / 10000;
           }
         }
@@ -464,11 +559,15 @@ static bool _negotiate_streaming_parameters(videod_streaming_interface_t const *
       param->dwMaxPayloadTransferSize = 0;
     } else {
       uint_fast32_t frame_size = param->dwMaxVideoFrameSize;
+      uint_fast32_t payload_size;
       if (!interval_ms) {
-        param->dwMaxPayloadTransferSize = frame_size + 2;
+        payload_size = frame_size + 2;
       } else {
-        param->dwMaxPayloadTransferSize = (frame_size + interval_ms - 1) / interval_ms + 2;
+        payload_size = (frame_size + interval_ms - 1) / interval_ms + 2;
       }
+      if (CFG_TUD_VIDEO_STREAMING_EP_BUFSIZE < payload_size)
+        payload_size = CFG_TUD_VIDEO_STREAMING_EP_BUFSIZE;
+      param->dwMaxPayloadTransferSize = payload_size;
     }
     return true;
   }
@@ -482,10 +581,12 @@ static bool _negotiate_streaming_parameters(videod_streaming_interface_t const *
 static bool _close_vc_itf(uint8_t rhport, videod_interface_t *self)
 {
   tusb_desc_vc_itf_t const *vc = _get_desc_vc(self);
+
   /* The next descriptor after the class-specific VC interface header descriptor. */
-  void const *cur = (void const*)vc + vc->std.bLength + vc->ctl.bLength;
+  void const *cur = (uint8_t const*)vc + vc->std.bLength + vc->ctl.bLength;
+
   /* The end of the video control interface descriptor. */
-  void const *end = (void const*)vc + vc->std.bLength + vc->ctl.wTotalLength;
+  void const *end = _end_of_control_descriptor(vc);
   if (vc->std.bNumEndpoints) {
     /* Find the notification endpoint descriptor. */
     cur = _find_desc(cur, end, TUSB_DESC_ENDPOINT);
@@ -504,10 +605,11 @@ static bool _close_vc_itf(uint8_t rhport, videod_interface_t *self)
 static bool _open_vc_itf(uint8_t rhport, videod_interface_t *self, uint_fast8_t altnum)
 {
   TU_LOG2("    open VC %d\n", altnum);
-  void const *beg = self->beg;
-  void const *end = beg + self->len;
+  uint8_t const *beg = self->beg;
+  uint8_t const *end = beg + self->len;
+
   /* The first descriptor is a video control interface descriptor. */
-  void const *cur = _find_desc_itf(beg, end, _desc_itfnum(beg), altnum);
+  uint8_t const *cur = _find_desc_itf(beg, end, _desc_itfnum(beg), altnum);
   TU_LOG2("    cur %d\n", cur - beg);
   TU_VERIFY(cur < end);
 
@@ -517,7 +619,8 @@ static bool _open_vc_itf(uint8_t rhport, videod_interface_t *self, uint_fast8_t
   TU_ASSERT(vc->ctl.bInCollection <= CFG_TUD_VIDEO_STREAMING);
 
   /* Update to point the end of the video control interface descriptor. */
-  end  = cur + vc->std.bLength + vc->ctl.wTotalLength;
+  end = _end_of_control_descriptor(cur);
+
   /* Advance to the next descriptor after the class-specific VC interface header descriptor. */
   cur += vc->std.bLength + vc->ctl.bLength;
   TU_LOG2("    bNumEndpoints %d\n", vc->std.bNumEndpoints);
@@ -532,7 +635,7 @@ static bool _open_vc_itf(uint8_t rhport, videod_interface_t *self, uint_fast8_t
     /* Open the notification endpoint */
     TU_ASSERT(usbd_edpt_open(rhport, notif));
   }
-  self->cur = (void const*)vc - beg;
+  self->cur = (uint16_t) ((uint8_t const*)vc - beg);
   return true;
 }
 
@@ -544,36 +647,39 @@ static bool _open_vs_itf(uint8_t rhport, videod_streaming_interface_t *stm, uint
 {
   uint_fast8_t i;
   TU_LOG2("    reopen VS %d\n", altnum);
-  void const *desc = _videod_itf[stm->index_vc].beg;
+  uint8_t const *desc = _videod_itf[stm->index_vc].beg;
 
   /* Close endpoints of previous settings. */
   for (i = 0; i < TU_ARRAY_SIZE(stm->desc.ep); ++i) {
     uint_fast16_t ofs_ep = stm->desc.ep[i];
     if (!ofs_ep) break;
-    uint_fast8_t  ep_adr = _desc_ep_addr(desc + ofs_ep);
+    uint8_t  ep_adr = _desc_ep_addr(desc + ofs_ep);
     usbd_edpt_close(rhport, ep_adr);
     stm->desc.ep[i] = 0;
     TU_LOG2("    close EP%02x\n", ep_adr);
   }
+
   /* clear transfer management information */
   stm->buffer  = NULL;
   stm->bufsize = 0;
   stm->offset  = 0;
 
   /* Find a alternate interface */
-  void const *beg = desc + stm->desc.beg;
-  void const *end = desc + stm->desc.end;
-  void const *cur = _find_desc_itf(beg, end, _desc_itfnum(beg), altnum);
+  uint8_t const *beg = desc + stm->desc.beg;
+  uint8_t const *end = desc + stm->desc.end;
+  uint8_t const *cur = _find_desc_itf(beg, end, _desc_itfnum(beg), altnum);
   TU_VERIFY(cur < end);
+
   uint_fast8_t numeps = ((tusb_desc_interface_t const *)cur)->bNumEndpoints;
   TU_ASSERT(numeps <= TU_ARRAY_SIZE(stm->desc.ep));
-  stm->desc.cur = cur - desc; /* Save the offset of the new settings */
+  stm->desc.cur = (uint16_t) (cur - desc); /* Save the offset of the new settings */
   if (!altnum) {
     /* initialize streaming settings */
     stm->max_payload_transfer_size = 0;
     video_probe_and_commit_control_t *param =
       (video_probe_and_commit_control_t *)&stm->ep_buf;
     tu_memclr(param, sizeof(*param));
+    TU_LOG2("    done 0\n");
     return _update_streaming_parameters(stm, param);
   }
   /* Open endpoints of the new settings. */
@@ -594,7 +700,7 @@ static bool _open_vs_itf(uint8_t rhport, videod_streaming_interface_t *stm, uint
       stm->max_payload_transfer_size = max_size;
     }
     TU_ASSERT(usbd_edpt_open(rhport, ep));
-    stm->desc.ep[i] = cur - desc;
+    stm->desc.ep[i] = (uint16_t) (cur - desc);
     TU_LOG2("    open EP%02x\n", _desc_ep_addr(cur));
   }
   /* initialize payload header */
@@ -602,6 +708,7 @@ static bool _open_vs_itf(uint8_t rhport, videod_streaming_interface_t *stm, uint
   hdr->bHeaderLength = sizeof(*hdr);
   hdr->bmHeaderInfo  = 0;
 
+  TU_LOG2("    done\n");
   return true;
 }
 
@@ -674,7 +781,7 @@ static int handle_video_ctl_cs_req(uint8_t rhport, uint8_t stage,
           if (stage == CONTROL_STAGE_SETUP) {
             TU_VERIFY(1 == request->wLength, VIDEO_ERROR_UNKNOWN);
             TU_VERIFY(tud_control_xfer(rhport, request, &self->power_mode, sizeof(self->power_mode)), VIDEO_ERROR_UNKNOWN);
-          } else if (stage == CONTROL_STAGE_ACK) {
+          } else if (stage == CONTROL_STAGE_DATA) {
             if (tud_video_power_mode_cb) return tud_video_power_mode_cb(ctl_idx, self->power_mode);
           }
           return VIDEO_ERROR_NONE;
@@ -816,10 +923,10 @@ static int handle_video_stm_cs_req(uint8_t rhport, uint8_t stage,
       switch (request->bRequest) {
         case VIDEO_REQUEST_SET_CUR:
           if (stage == CONTROL_STAGE_SETUP) {
-            TU_VERIFY(sizeof(video_probe_and_commit_control_t) == request->wLength, VIDEO_ERROR_UNKNOWN);
+            TU_VERIFY(sizeof(video_probe_and_commit_control_t) >= request->wLength, VIDEO_ERROR_UNKNOWN);
             TU_VERIFY(tud_control_xfer(rhport, request, self->ep_buf, sizeof(video_probe_and_commit_control_t)),
                       VIDEO_ERROR_UNKNOWN);
-          } else if (stage == CONTROL_STAGE_ACK) {
+          } else if (stage == CONTROL_STAGE_DATA) {
             TU_VERIFY(_update_streaming_parameters(self, (video_probe_and_commit_control_t*)self->ep_buf),
                       VIDEO_ERROR_INVALID_VALUE_WITHIN_RANGE);
           }
@@ -843,7 +950,7 @@ static int handle_video_stm_cs_req(uint8_t rhport, uint8_t stage,
             video_probe_and_commit_control_t tmp;
             tmp = *(video_probe_and_commit_control_t*)&self->ep_buf;
             TU_VERIFY(_negotiate_streaming_parameters(self, request->bRequest, &tmp), VIDEO_ERROR_INVALID_VALUE_WITHIN_RANGE);
-            TU_VERIFY(tud_control_xfer(rhport, request, self->ep_buf, sizeof(video_probe_and_commit_control_t)), VIDEO_ERROR_UNKNOWN);
+            TU_VERIFY(tud_control_xfer(rhport, request, &tmp, sizeof(tmp)), VIDEO_ERROR_UNKNOWN);
           }
           return VIDEO_ERROR_NONE;
 
@@ -860,7 +967,7 @@ static int handle_video_stm_cs_req(uint8_t rhport, uint8_t stage,
           if (stage == CONTROL_STAGE_SETUP)
           {
             TU_VERIFY(1 == request->wLength, VIDEO_ERROR_UNKNOWN);
-            TU_VERIFY(tud_control_xfer(rhport, request, (uint8_t*)(uintptr_t) &_cap_get_set, sizeof(_cap_get_set)), VIDEO_ERROR_UNKNOWN);
+            TU_VERIFY(tud_control_xfer(rhport, request, (uint8_t*)(uintptr_t)&_cap_get_set, sizeof(_cap_get_set)), VIDEO_ERROR_UNKNOWN);
           }
           return VIDEO_ERROR_NONE;
 
@@ -872,9 +979,9 @@ static int handle_video_stm_cs_req(uint8_t rhport, uint8_t stage,
       switch (request->bRequest) {
         case VIDEO_REQUEST_SET_CUR:
           if (stage == CONTROL_STAGE_SETUP) {
-            TU_VERIFY(sizeof(video_probe_and_commit_control_t) == request->wLength, VIDEO_ERROR_UNKNOWN);
+            TU_VERIFY(sizeof(video_probe_and_commit_control_t) >= request->wLength, VIDEO_ERROR_UNKNOWN);
             TU_VERIFY(tud_control_xfer(rhport, request, self->ep_buf, sizeof(video_probe_and_commit_control_t)), VIDEO_ERROR_UNKNOWN);
-          } else if (stage == CONTROL_STAGE_ACK) {
+          } else if (stage == CONTROL_STAGE_DATA) {
             TU_VERIFY(_update_streaming_parameters(self, (video_probe_and_commit_control_t*)self->ep_buf), VIDEO_ERROR_INVALID_VALUE_WITHIN_RANGE);
             if (tud_video_commit_cb) {
               return tud_video_commit_cb(self->index_vc, self->index_vs, (video_probe_and_commit_control_t*)self->ep_buf);
@@ -942,7 +1049,6 @@ static int handle_video_stm_req(uint8_t rhport, uint8_t stage,
 
     default: return VIDEO_ERROR_INVALID_REQUEST;
   }
-  return VIDEO_ERROR_UNKNOWN;
 }
 
 //--------------------------------------------------------------------+
@@ -975,8 +1081,8 @@ bool tud_video_n_frame_xfer(uint_fast8_t ctl_idx, uint_fast8_t stm_idx, void *bu
   if (!stm || !stm->desc.ep[0] || stm->buffer) return false;
 
   /* Find EP address */
-  void const *desc = _videod_itf[stm->index_vc].beg;
-  uint_fast8_t ep_addr = 0;
+  uint8_t const *desc = _videod_itf[stm->index_vc].beg;
+  uint8_t ep_addr = 0;
   for (uint_fast8_t i = 0; i < CFG_TUD_VIDEO_STREAMING; ++i) {
     uint_fast16_t ofs_ep = stm->desc.ep[i];
     if (!ofs_ep) continue;
@@ -985,7 +1091,7 @@ bool tud_video_n_frame_xfer(uint_fast8_t ctl_idx, uint_fast8_t stm_idx, void *bu
   }
   if (!ep_addr) return false;
 
-  TU_VERIFY( usbd_edpt_claim(0, ep_addr));
+  TU_VERIFY( usbd_edpt_claim(0, ep_addr) );
   /* update the packet header */
   tusb_video_payload_header_t *hdr = (tusb_video_payload_header_t*)stm->ep_buf;
   hdr->FrameID   ^= 1;
@@ -994,7 +1100,7 @@ bool tud_video_n_frame_xfer(uint_fast8_t ctl_idx, uint_fast8_t stm_idx, void *bu
   stm->buffer     = (uint8_t*)buffer;
   stm->bufsize    = bufsize;
   uint_fast16_t pkt_len = _prepare_in_payload(stm);
-  TU_ASSERT( usbd_edpt_xfer(0, ep_addr, stm->ep_buf, pkt_len), 0);
+  TU_ASSERT( usbd_edpt_xfer(0, ep_addr, stm->ep_buf, (uint16_t) pkt_len), 0);
   return true;
 }
 
@@ -1034,7 +1140,7 @@ uint16_t videod_open(uint8_t rhport, tusb_desc_interface_t const * itf_desc, uin
 
   /* Find available interface */
   videod_interface_t *self = NULL;
-  uint_fast8_t ctl_idx;
+  uint8_t ctl_idx;
   for (ctl_idx = 0; ctl_idx < CFG_TUD_VIDEO; ++ctl_idx) {
     if (_videod_itf[ctl_idx].beg) continue;
     self = &_videod_itf[ctl_idx];
@@ -1042,19 +1148,21 @@ uint16_t videod_open(uint8_t rhport, tusb_desc_interface_t const * itf_desc, uin
   }
   TU_ASSERT(ctl_idx < CFG_TUD_VIDEO, 0);
 
-  void const *end = (void const*)itf_desc + max_len;
-  self->beg = itf_desc;
+  uint8_t const *end = (uint8_t const*)itf_desc + max_len;
+  self->beg = (uint8_t const*) itf_desc;
   self->len = max_len;
+
   /*------------- Video Control Interface -------------*/
   TU_VERIFY(_open_vc_itf(rhport, self, 0), 0);
   tusb_desc_vc_itf_t const *vc = _get_desc_vc(self);
   uint_fast8_t bInCollection   = vc->ctl.bInCollection;
+
   /* Find the end of the video interface descriptor */
   void const *cur = _next_desc_itf(itf_desc, end);
-  for (uint_fast8_t stm_idx = 0; stm_idx < bInCollection; ++stm_idx) {
+  for (uint8_t stm_idx = 0; stm_idx < bInCollection; ++stm_idx) {
     videod_streaming_interface_t *stm = NULL;
     /* find free streaming interface handle */
-    for (uint_fast8_t i = 0; i < CFG_TUD_VIDEO_STREAMING; ++i) {
+    for (uint8_t i = 0; i < CFG_TUD_VIDEO_STREAMING; ++i) {
       if (_videod_streaming_itf[i].desc.beg) continue;
       stm = &_videod_streaming_itf[i];
       self->stm[stm_idx] = i;
@@ -1063,12 +1171,12 @@ uint16_t videod_open(uint8_t rhport, tusb_desc_interface_t const * itf_desc, uin
     TU_ASSERT(stm, 0);
     stm->index_vc = ctl_idx;
     stm->index_vs = stm_idx;
-    stm->desc.beg = (uintptr_t)cur - (uintptr_t)itf_desc;
+    stm->desc.beg = (uint16_t) ((uintptr_t)cur - (uintptr_t)itf_desc);
     cur = _next_desc_itf(cur, end);
-    stm->desc.end = (uintptr_t)cur - (uintptr_t)itf_desc;
+    stm->desc.end = (uint16_t) ((uintptr_t)cur - (uintptr_t)itf_desc);
   }
-  self->len = (uintptr_t)cur - (uintptr_t)itf_desc;
-  return (uintptr_t)cur - (uintptr_t)itf_desc;
+  self->len = (uint16_t) ((uintptr_t)cur - (uintptr_t)itf_desc);
+  return (uint16_t) ((uintptr_t)cur - (uintptr_t)itf_desc);
 }
 
 // Invoked when a control transfer occurred on an interface of this class
@@ -1099,7 +1207,7 @@ bool videod_control_xfer_cb(uint8_t rhport, uint8_t stage, tusb_control_request_
   for (itf = 0; itf < CFG_TUD_VIDEO_STREAMING; ++itf) {
     videod_streaming_interface_t *stm = &_videod_streaming_itf[itf];
     if (!stm->desc.beg) continue;
-    void const *desc = _videod_itf[stm->index_vc].beg;
+    uint8_t const *desc = _videod_itf[stm->index_vc].beg;
     if (itfnum == _desc_itfnum(desc + stm->desc.beg)) break;
   }
 
@@ -1125,7 +1233,7 @@ bool videod_xfer_cb(uint8_t rhport, uint8_t ep_addr, xfer_result_t result, uint3
     uint_fast16_t const ep_ofs = stm->desc.ep[0];
     if (!ep_ofs) continue;
     ctl = &_videod_itf[stm->index_vc];
-    void const *desc = ctl->beg;
+    uint8_t const *desc = ctl->beg;
     if (ep_addr == _desc_ep_addr(desc + ep_ofs)) break;
   }
 
@@ -1134,7 +1242,7 @@ bool videod_xfer_cb(uint8_t rhport, uint8_t ep_addr, xfer_result_t result, uint3
     /* Claim the endpoint */
     TU_VERIFY( usbd_edpt_claim(rhport, ep_addr), 0);
     uint_fast16_t pkt_len = _prepare_in_payload(stm);
-    TU_ASSERT( usbd_edpt_xfer(rhport, ep_addr, stm->ep_buf, pkt_len), 0);
+    TU_ASSERT( usbd_edpt_xfer(rhport, ep_addr, stm->ep_buf, (uint16_t) pkt_len), 0);
   } else {
     stm->buffer  = NULL;
     stm->bufsize = 0;