replace printer_to_hid example with printer_to_cdc example

fix printer GET_DEVICE_ID request weird wIndex (interface high, alt low)

10 files changed, 155 insertions, 228 deletions

diff --git a/examples/device/CMakeLists.txt b/examples/device/CMakeLists.txt
index dbcb8df6a..7173f455e 100644
--- a/examples/device/CMakeLists.txt
+++ b/examples/device/CMakeLists.txt
@@ -30,7 +30,7 @@ set(EXAMPLE_LIST
   msc_dual_lun
   mtp
   net_lwip_webserver
-  printer_to_hid
+  printer_to_cdc
   uac2_headset
   uac2_speaker_fb
   usbtmc
diff --git a/examples/device/printer_to_hid/CMakeLists.txt b/examples/device/printer_to_cdc/CMakeLists.txt
index f58759059..3c8ab3653 100644
--- a/examples/device/printer_to_hid/CMakeLists.txt
+++ b/examples/device/printer_to_cdc/CMakeLists.txt
@@ -2,7 +2,7 @@ cmake_minimum_required(VERSION 3.20)
 
 include(${CMAKE_CURRENT_SOURCE_DIR}/../../../hw/bsp/family_support.cmake)
 
-project(printer_to_hid C CXX ASM)
+project(printer_to_cdc C CXX ASM)
 
 # Checks this example is valid for the family and initializes the project
 family_initialize_project(${PROJECT_NAME} ${CMAKE_CURRENT_LIST_DIR})
diff --git a/examples/device/printer_to_hid/Makefile b/examples/device/printer_to_cdc/Makefile
index 1a4b428dc..1a4b428dc 100644
--- a/examples/device/printer_to_hid/Makefile
+++ b/examples/device/printer_to_cdc/Makefile
diff --git a/examples/device/printer_to_cdc/src/main.c b/examples/device/printer_to_cdc/src/main.c
new file mode 100644
index 000000000..aba79025c
--- /dev/null
+++ b/examples/device/printer_to_cdc/src/main.c
@@ -0,0 +1,115 @@
+/*
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2026 Ha Thach (tinyusb.org)
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ *
+ */
+
+/* This example demonstrates a USB Printer + CDC composite device.
+ * Data received on the Printer interface is forwarded to the CDC serial port,
+ * and data received on the CDC serial port is forwarded back to the Printer interface.
+ *
+ * To test:
+ *   1. Flash the device
+ *   2. Open a serial terminal on the CDC port (e.g. /dev/ttyACM0)
+ *   3. Send data to the printer: echo "hello" > /dev/usb/lp0
+ *   4. The data appears on the CDC serial terminal
+ *   5. Type in the serial terminal to send data back through the printer TX
+ */
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+
+#include "bsp/board_api.h"
+#include "tusb.h"
+
+#include "usb_descriptors.h"
+
+// -------------------------------------------------------------------+
+// Tasks
+// -------------------------------------------------------------------+
+
+// Forward data from Printer RX to CDC TX
+static void printer_to_cdc_task(void) {
+  if (tud_printer_read_available() == 0 || !tud_cdc_write_available()) {
+    return;
+  }
+
+  uint8_t buf[64];
+  uint32_t count = tud_printer_read(buf, sizeof(buf));
+  if (count > 0) {
+    tud_cdc_write(buf, count);
+    tud_cdc_write_flush();
+  }
+}
+
+// Forward data from CDC RX to Printer TX
+static void cdc_to_printer_task(void) {
+  if (tud_cdc_available() == 0 || !tud_printer_write_available()) {
+    return;
+  }
+
+  uint8_t buf[64];
+  uint32_t count = tud_cdc_read(buf, sizeof(buf));
+  if (count > 0) {
+    tud_printer_write(buf, count);
+    tud_printer_write_flush();
+  }
+}
+
+int main(void) {
+  board_init();
+  // init device stack on configured roothub port
+  tusb_rhport_init_t dev_init = {.role = TUSB_ROLE_DEVICE, .speed = TUSB_SPEED_AUTO};
+  tusb_init(BOARD_TUD_RHPORT, &dev_init);
+  board_init_after_tusb();
+
+  while (1) {
+    tud_task();             // tinyusb device task
+    printer_to_cdc_task();  // forward printer data to CDC
+    cdc_to_printer_task();  // forward CDC data to printer
+  }
+}
+
+//--------------------------------------------------------------------+
+// Printer callbacks
+//--------------------------------------------------------------------+
+
+void tud_printer_rx_cb(uint8_t itf) {
+  (void)itf;
+}
+
+// IEEE 1284 Device ID: first 2 bytes are big-endian total length (including the 2 length bytes).
+// The rest is the Device ID string using standard abbreviated keys.
+static const char printer_device_id[] =
+  "\x00\x34" // total length = 52 = 0x0034 (big-endian)
+  "MFG:TinyUSB;"
+  "MDL:Printer to CDC;"
+  "CMD:PS;"
+  "CLS:PRINTER;";
+
+TU_VERIFY_STATIC(sizeof(printer_device_id) - 1 == 52, "device ID length mismatch");
+
+uint8_t const *tud_printer_get_device_id_cb(uint8_t itf) {
+  (void)itf;
+  return (uint8_t const *)printer_device_id;
+}
diff --git a/examples/device/printer_to_hid/src/tusb_config.h b/examples/device/printer_to_cdc/src/tusb_config.h
index 0988be166..50ef41762 100644
--- a/examples/device/printer_to_hid/src/tusb_config.h
+++ b/examples/device/printer_to_cdc/src/tusb_config.h
@@ -91,15 +91,19 @@ extern "C" {
 #endif
 
 //------------- CLASS -------------//
-#define CFG_TUD_HID     1
-#define CFG_TUD_CDC     0
+#define CFG_TUD_HID     0
+#define CFG_TUD_CDC     1
 #define CFG_TUD_MSC     0
 #define CFG_TUD_MIDI    0
 #define CFG_TUD_VENDOR  0
 #define CFG_TUD_PRINTER 1
 
-// HID buffer size Should be sufficient to hold ID (if any) + Data
-#define CFG_TUD_HID_EP_BUFSIZE 16
+// CDC FIFO size of TX and RX
+#define CFG_TUD_CDC_RX_BUFSIZE   (TUD_OPT_HIGH_SPEED ? 512 : 64)
+#define CFG_TUD_CDC_TX_BUFSIZE   (TUD_OPT_HIGH_SPEED ? 512 : 64)
+
+// CDC Endpoint transfer buffer size
+#define CFG_TUD_CDC_EP_BUFSIZE   (TUD_OPT_HIGH_SPEED ? 512 : 64)
 
 // Printer buffer sizes
 #define CFG_TUD_PRINTER_RX_BUFSIZE 512
diff --git a/examples/device/printer_to_hid/src/usb_descriptors.c b/examples/device/printer_to_cdc/src/usb_descriptors.c
index 1cbabb02e..30d309ed4 100644
--- a/examples/device/printer_to_hid/src/usb_descriptors.c
+++ b/examples/device/printer_to_cdc/src/usb_descriptors.c
@@ -1,7 +1,7 @@
 /*
  * The MIT License (MIT)
  *
- * Copyright (c) 2019 Ha Thach (tinyusb.org)
+ * Copyright (c) 2026 Ha Thach (tinyusb.org)
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
@@ -29,7 +29,7 @@
 #include "usb_descriptors.h"
 
 #define USB_VID   0xCafe
-#define USB_PID   0x4004
+#define USB_PID   0x4005
 #define USB_BCD   0x0200
 
 //--------------------------------------------------------------------+
@@ -39,9 +39,12 @@ static tusb_desc_device_t const desc_device = {
   .bLength            = sizeof(tusb_desc_device_t),
   .bDescriptorType    = TUSB_DESC_DEVICE,
   .bcdUSB             = USB_BCD,
-  .bDeviceClass       = 0x00,
-  .bDeviceSubClass    = 0x00,
-  .bDeviceProtocol    = 0x00,
+
+  // Use Interface Association Descriptor (IAD) for CDC
+  // As required by USB Specs IAD's subclass must be common class (2) and protocol must be IAD (1)
+  .bDeviceClass       = TUSB_CLASS_MISC,
+  .bDeviceSubClass    = MISC_SUBCLASS_COMMON,
+  .bDeviceProtocol    = MISC_PROTOCOL_IAD,
   .bMaxPacketSize0    = CFG_TUD_ENDPOINT0_SIZE,
 
   .idVendor           = USB_VID,
@@ -60,30 +63,22 @@ uint8_t const *tud_descriptor_device_cb(void) {
 }
 
 //--------------------------------------------------------------------+
-// HID Report Descriptor
-//--------------------------------------------------------------------+
-static uint8_t const desc_hid_report[] = {
-  TUD_HID_REPORT_DESC_KEYBOARD(HID_REPORT_ID(REPORT_ID_KEYBOARD))
-};
-
-uint8_t const *tud_hid_descriptor_report_cb(uint8_t instance) {
-  (void)instance;
-  return desc_hid_report;
-}
-
-//--------------------------------------------------------------------+
 // Configuration Descriptor
 //--------------------------------------------------------------------+
 
 // Endpoint numbers
 #if defined(TUD_ENDPOINT_ONE_DIRECTION_ONLY)
-  #define EPNUM_HID         0x81
-  #define EPNUM_PRINTER_OUT 0x02
-  #define EPNUM_PRINTER_IN  0x83
+  #define EPNUM_CDC_NOTIF   0x81
+  #define EPNUM_CDC_OUT     0x02
+  #define EPNUM_CDC_IN      0x83
+  #define EPNUM_PRINTER_OUT 0x04
+  #define EPNUM_PRINTER_IN  0x85
 #else
-  #define EPNUM_HID         0x81
-  #define EPNUM_PRINTER_OUT 0x02
-  #define EPNUM_PRINTER_IN  0x82
+  #define EPNUM_CDC_NOTIF   0x81
+  #define EPNUM_CDC_OUT     0x02
+  #define EPNUM_CDC_IN      0x82
+  #define EPNUM_PRINTER_OUT 0x03
+  #define EPNUM_PRINTER_IN  0x83
 #endif
 
 // full speed configuration
@@ -91,9 +86,8 @@ static uint8_t const desc_fs_configuration[] = {
   // Config number, interface count, string index, total length, attribute, power in mA
   TUD_CONFIG_DESCRIPTOR(1, ITF_NUM_TOTAL, 0, CONFIG_TOTAL_LEN, 0x00, 100),
 
-  // Interface number, string index, protocol, report descriptor len, EP In address, size & polling interval
-  TUD_HID_DESCRIPTOR(ITF_NUM_HID, 4, HID_ITF_PROTOCOL_NONE, sizeof(desc_hid_report), EPNUM_HID,
-                     CFG_TUD_HID_EP_BUFSIZE, 5),
+  // Interface number, string index, EP notification address and size, EP data address (out, in) and size.
+  TUD_CDC_DESCRIPTOR(ITF_NUM_CDC, 4, EPNUM_CDC_NOTIF, 16, EPNUM_CDC_OUT, EPNUM_CDC_IN, 64),
 
   // Interface number, string index, EP Bulk Out address, EP Bulk In address, EP size
   TUD_PRINTER_DESCRIPTOR(ITF_NUM_PRINTER, 5, EPNUM_PRINTER_OUT, EPNUM_PRINTER_IN, 64),
@@ -104,8 +98,7 @@ static uint8_t const desc_fs_configuration[] = {
 static uint8_t const desc_hs_configuration[] = {
   TUD_CONFIG_DESCRIPTOR(1, ITF_NUM_TOTAL, 0, CONFIG_TOTAL_LEN, 0x00, 100),
 
-  TUD_HID_DESCRIPTOR(ITF_NUM_HID, 4, HID_ITF_PROTOCOL_NONE, sizeof(desc_hid_report), EPNUM_HID,
-                     CFG_TUD_HID_EP_BUFSIZE, 5),
+  TUD_CDC_DESCRIPTOR(ITF_NUM_CDC, 4, EPNUM_CDC_NOTIF, 16, EPNUM_CDC_OUT, EPNUM_CDC_IN, 512),
 
   TUD_PRINTER_DESCRIPTOR(ITF_NUM_PRINTER, 5, EPNUM_PRINTER_OUT, EPNUM_PRINTER_IN, 512),
 };
@@ -119,9 +112,9 @@ static tusb_desc_device_qualifier_t const desc_device_qualifier = {
   .bDescriptorType    = TUSB_DESC_DEVICE_QUALIFIER,
   .bcdUSB             = USB_BCD,
 
-  .bDeviceClass       = 0x00,
-  .bDeviceSubClass    = 0x00,
-  .bDeviceProtocol    = 0x00,
+  .bDeviceClass       = TUSB_CLASS_MISC,
+  .bDeviceSubClass    = MISC_SUBCLASS_COMMON,
+  .bDeviceProtocol    = MISC_PROTOCOL_IAD,
 
   .bMaxPacketSize0    = CFG_TUD_ENDPOINT0_SIZE,
   .bNumConfigurations = 0x01,
@@ -166,7 +159,7 @@ enum {
   STRID_MANUFACTURER,
   STRID_PRODUCT,
   STRID_SERIAL,
-  STRID_HID,
+  STRID_CDC,
   STRID_PRINTER,
 };
 
@@ -175,7 +168,7 @@ static char const *string_desc_arr[] = {
   "TinyUSB",                     // 1: Manufacturer
   "TinyUSB Device",              // 2: Product
   NULL,                          // 3: Serial, use unique ID if possible
-  "TinyUSB HID",                 // 4: HID Interface
+  "TinyUSB CDC",                 // 4: CDC Interface
   "TinyUSB Printer",             // 5: Printer Interface
 };
 
diff --git a/examples/device/printer_to_hid/src/usb_descriptors.h b/examples/device/printer_to_cdc/src/usb_descriptors.h
index 20c34f151..830593b4d 100644
--- a/examples/device/printer_to_hid/src/usb_descriptors.h
+++ b/examples/device/printer_to_cdc/src/usb_descriptors.h
@@ -1,7 +1,7 @@
 /*
  * The MIT License (MIT)
  *
- * Copyright (c) 2019 Ha Thach (tinyusb.org)
+ * Copyright (c) 2026 Ha Thach (tinyusb.org)
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
@@ -25,17 +25,13 @@
 #ifndef USB_DESCRIPTORS_H_
 #define USB_DESCRIPTORS_H_
 
-// HID report ID
 enum {
-  REPORT_ID_KEYBOARD = 1,
-};
-
-enum {
-  ITF_NUM_HID,
+  ITF_NUM_CDC,
+  ITF_NUM_CDC_DATA,
   ITF_NUM_PRINTER,
   ITF_NUM_TOTAL,
 };
 
-#define CONFIG_TOTAL_LEN (TUD_CONFIG_DESC_LEN + TUD_HID_DESC_LEN + TUD_PRINTER_DESC_LEN)
+#define CONFIG_TOTAL_LEN (TUD_CONFIG_DESC_LEN + TUD_CDC_DESC_LEN + TUD_PRINTER_DESC_LEN)
 
 #endif /* USB_DESCRIPTORS_H_ */
diff --git a/examples/device/printer_to_hid/CMakePresets.json b/examples/device/printer_to_hid/CMakePresets.json
deleted file mode 100644
index 5cd8971e9..000000000
--- a/examples/device/printer_to_hid/CMakePresets.json
+++ /dev/null
@@ -1,6 +0,0 @@
-{
-  "version": 6,
-  "include": [
-    "../../../hw/bsp/BoardPresets.json"
-  ]
-}
diff --git a/examples/device/printer_to_hid/README.md b/examples/device/printer_to_hid/README.md
deleted file mode 100644
index e69de29bb..000000000
--- a/examples/device/printer_to_hid/README.md
+++ /dev/null
diff --git a/examples/device/printer_to_hid/src/main.c b/examples/device/printer_to_hid/src/main.c
deleted file mode 100644
index 0d14147b4..000000000
--- a/examples/device/printer_to_hid/src/main.c
+++ /dev/null
@@ -1,175 +0,0 @@
-/*
- * The MIT License (MIT)
- *
- * Copyright (c) 2026 Ha Thach (tinyusb.org)
- *
- * Permission is hereby granted, free of charge, to any person obtaining a copy
- * of this software and associated documentation files (the "Software"), to deal
- * in the Software without restriction, including without limitation the rights
- * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
- * copies of the Software, and to permit persons to whom the Software is
- * furnished to do so, subject to the following conditions:
- *
- * The above copyright notice and this permission notice shall be included in
- * all copies or substantial portions of the Software.
- *
- * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
- * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
- * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
- * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
- * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
- * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
- * THE SOFTWARE.
- *
- */
-
-#include <stdlib.h>
-#include <stdio.h>
-#include <string.h>
-
-#include "bsp/board_api.h"
-#include "tusb.h"
-
-#include "usb_descriptors.h"
-
-// -------------------------------------------------------------------+
-// Variables
-// -------------------------------------------------------------------+
-
-// next keycode to send on usb/hid
-static uint8_t next_keycode = 0;
-// next key modifiers to send on usb/hid
-static uint8_t next_modifiers = 0;
-// whether the next usb/hid report must be NULL to release the last keystroke
-static bool next_keycode_is_release = false;
-
-
-// -------------------------------------------------------------------+
-// Tasks
-// -------------------------------------------------------------------+
-
-// Every 10ms, we will place HID data in the usb/hid endpoint, ready to
-// sent to the host when required. The tasks will read the keycode in
-// next_keycode and place it in the HID report, then set next_is_null
-// such that the key is released by the next report. This seem to help
-// stroking the same key twice when the character is repeated in the data.
-static void hid_tx_task(void) {
-  // Poll every 10ms
-  const uint32_t  interval_ms = 10;
-  static uint32_t start_ms    = 0;
-
-  if (!tud_hid_ready()) {
-    return;
-  }
-
-  if (tusb_time_millis_api() - start_ms < interval_ms) {
-    return; // not enough time
-  }
-  start_ms += interval_ms;
-
-  if (next_keycode_is_release || next_keycode == 0) {
-    tud_hid_keyboard_report(1, 0, NULL);
-    next_keycode_is_release = false;
-    return;
-  }
-
-  uint8_t keycode_array[6] = {0};
-  keycode_array[0]         = next_keycode;
-  tud_hid_keyboard_report(1, next_modifiers, keycode_array);
-  next_keycode_is_release = true;
-  next_keycode            = 0;
-}
-
-// Read one byte from printer FIFO and translate to HID keycode.
-// Only a-zA-Z0-9 are translated; everything else becomes space.
-static void printer_to_hid_task(void) {
-  if (next_keycode != 0) {
-    return; // previous key not yet sent
-  }
-
-  uint8_t ch;
-  if (tud_printer_read(&ch, 1) == 0) {
-    return; // no data available
-  }
-
-  uint8_t m = 0;
-  if ('a' <= ch && ch <= 'z') {
-    ch = (uint8_t)(ch - 'a' + HID_KEY_A);
-  } else if ('A' <= ch && ch <= 'Z') {
-    ch = (uint8_t)(ch - 'A' + HID_KEY_A);
-    m = KEYBOARD_MODIFIER_LEFTSHIFT;
-  } else if ('1' <= ch && ch <= '9') {
-    ch = (uint8_t)(ch - '1' + HID_KEY_1);
-  } else if (ch == '0') {
-    ch = HID_KEY_0;
-  } else {
-    ch = HID_KEY_SPACE;
-  }
-
-  next_keycode   = ch;
-  next_modifiers = m;
-}
-
-int main(void) {
-  board_init();
-  // init device and host stack on configured roothub port
-  tusb_rhport_init_t dev_init = {.role = TUSB_ROLE_DEVICE, .speed = TUSB_SPEED_AUTO};
-  tusb_init(BOARD_TUD_RHPORT, &dev_init);
-  board_init_after_tusb();
-
-  while (1) {
-    tud_task();            // tinyusb device task
-    printer_to_hid_task(); // read printer data and translate to HID keycodes
-    hid_tx_task();         // send keycodes to host via HID
-  }
-}
-
-
-//--------------------------------------------------------------------+
-// Printer callbacks
-//--------------------------------------------------------------------+
-
-void tud_printer_rx_cb(uint8_t itf) {
-  (void)itf;
-}
-
-// IEEE 1284 Device ID: first 2 bytes are big-endian total length (including the 2 length bytes).
-// The rest is the Device ID string using standard abbreviated keys.
-static const char printer_device_id[] =
-  "\x00\x34" // total length = 52 = 0x0034 (big-endian)
-  "MFG:TinyUSB;"
-  "MDL:Printer to HID;"
-  "CMD:PS;"
-  "CLS:PRINTER;";
-
-TU_VERIFY_STATIC(sizeof(printer_device_id) - 1 == 52, "device ID length mismatch");
-
-uint8_t const *tud_printer_get_device_id_cb(uint8_t itf) {
-  (void)itf;
-  return (uint8_t const *)printer_device_id;
-}
-
-
-//--------------------------------------------------------------------+
-// HID callbacks
-//--------------------------------------------------------------------+
-
-uint16_t tud_hid_get_report_cb(uint8_t instance, uint8_t report_id, hid_report_type_t report_type, uint8_t *buffer,
-                               uint16_t reqlen) {
-  (void)instance;
-  (void)report_id;
-  (void)report_type;
-  (void)buffer;
-  (void)reqlen;
-  return 0;
-}
-
-void tud_hid_set_report_cb(uint8_t instance, uint8_t report_id, hid_report_type_t report_type, const uint8_t *buffer,
-                           uint16_t bufsize) {
-  (void)instance;
-  (void)report_id;
-  (void)report_type;
-  (void)buffer;
-  (void)bufsize;
-  return;
-}