Add usbtmc class driver.

6 files changed, 841 insertions, 0 deletions

diff --git a/src/class/usbtmc/usbtmc.h b/src/class/usbtmc/usbtmc.h
new file mode 100644
index 000000000..846c0e38d
--- /dev/null
+++ b/src/class/usbtmc/usbtmc.h
@@ -0,0 +1,267 @@
+
+/*
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2019 N Conrad
+ *
+ * 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 file is part of the TinyUSB stack.
+ */
+
+#ifndef _TUSB_USBTMC_H__
+#define _TUSB_USBTMC_H__
+
+#include "common/tusb_common.h"
+
+
+/* Implements USBTMC Revision 1.0, April 14, 2003
+
+ String descriptors must have a "LANGID=0x409"/US English string.
+ Characters must be 0x20 (' ') to 0x7E ('~') ASCII,
+   But MUST not contain: "/:?\*
+   Also must not have leading or trailing space (' ')
+ Device descriptor must state USB version 0x0200 or greater
+
+ If USB488DeviceCapabilites.D2 = 1 (SR1), then there must be a INT endpoint.
+*/
+
+#define USBTMC_VERSION 0x0100
+#define USBTMC_488_VERSION 0x0100
+
+typedef enum {
+  USBTMC_MSGID_DEV_DEP_MSG_OUT = 1u,
+  USBTMC_MSGID_DEV_DEP_MSG_IN = 2u,
+  USBTMC_MSGID_VENDOR_SPECIFIC_MSG_OUT = 126u,
+  USBTMC_MSGID_VENDOR_SPECIFIC_IN = 127u,
+  USBTMC_MSGID_USB488_TRIGGER = 128u,
+} usbtmc_msgid_enum;
+
+/// \brief Message header (For BULK OUT and BULK IN); 4 bytes
+typedef struct TU_ATTR_PACKED
+{
+  uint8_t MsgID              ; ///< Message type ID (usbtmc_msgid_enum)
+  uint8_t bTag    		       ; ///< Transfer ID 1<=bTag<=255
+  uint8_t bTagInverse        ; ///< Complement of the tag
+  uint8_t _reserved           ; ///< Must be 0x00
+} usbtmc_msg_header_t;
+
+typedef struct TU_ATTR_PACKED
+{
+  usbtmc_msg_header_t header;
+  uint8_t data[8];
+} usbtmc_msg_generic_t;
+
+/* Uses on the bulk-out endpoint: */
+// Next 8 bytes are message-specific
+typedef struct TU_ATTR_PACKED {
+	usbtmc_msg_header_t header ; ///< Header
+	uint32_t TransferSize      ; ///< Transfer size; LSB first
+	struct {
+      uint8_t EOM  : 1         ; ///< EOM set on last byte
+  } bmTransferAttributes;
+  uint8_t _reserved[3];
+} usbtmc_msg_request_dev_dep_out;
+
+// Next 8 bytes are message-specific
+typedef struct TU_ATTR_PACKED {
+  usbtmc_msg_header_t header ; ///< Header
+  uint32_t TransferSize      ; ///< Transfer size; LSB first
+  struct {
+      uint8_t : 0;
+      uint8_t TermCharEnabled  : 1 ; ///< "The Bulk-IN transfer must terminate on the specified TermChar."; CAPABILITIES must list TermChar
+  } bmTransferAttributes;
+  uint8_t TermChar;
+  uint8_t _reserved[2];
+} usbtmc_msg_request_dev_dep_in;
+
+/* Bulk-in headers */
+
+typedef struct TU_ATTR_PACKED
+{
+  usbtmc_msg_header_t header;
+  uint32_t TransferSize;
+  struct {
+    uint8_t EOM: 1;           ///< Last byte of transfer is the end of the message
+    uint8_t UsingTermChar: 1; ///< Support TermChar && Request.TermCharEnabled && last char in transfer is TermChar
+  } bmTransferAttributes;
+  uint8_t _reserved[3];
+} usbtmc_msg_dev_dep_msg_in_header_t;
+
+
+/* Unsupported vendor things.... Are these ever used?*/
+
+typedef struct TU_ATTR_PACKED {
+  usbtmc_msg_header_t header ; ///< Header
+  uint32_t TransferSize      ; ///< Transfer size; LSB first
+  uint8_t _reserved[4];
+} usbtmc_msg_request_vendor_specific_out;
+
+
+typedef struct TU_ATTR_PACKED {
+  usbtmc_msg_header_t header ; ///< Header
+  uint32_t TransferSize      ; ///< Transfer size; LSB first
+  uint8_t _reserved[4];
+} usbtmc_msg_request_vendor_specific_in;
+
+// Control request type should use tusb_control_request_t
+
+/*
+typedef struct TU_ATTR_PACKED {
+  struct {
+    uint8_t Recipient  : 5         ; ///< EOM set on last byte
+    uint8_t Type       : 2         ; ///< EOM set on last byte
+    uint8_t DirectionToHost  : 1   ; ///< 0 is OUT, 1 is IN
+  } bmRequestType;
+  uint8_t bRequest                 ; ///< If bmRequestType.Type = Class, see usmtmc_request_type_enum
+  uint16_t wValue                  ;
+  uint16_t wIndex                  ;
+  uint16_t wLength                 ; // Number of bytes in data stage
+} usbtmc_class_specific_control_req;
+
+*/
+// bulk-in protocol errors
+enum {
+  USBTMC_BULK_IN_ERR_INCOMPLETE_HEADER = 1u,
+  USBTMC_BULK_IN_ERR_UNSUPPORTED = 2u,
+  USBTMC_BULK_IN_ERR_BAD_PARAMETER = 3u,
+  USBTMC_BULK_IN_ERR_DATA_TOO_SHORT = 4u,
+  USBTMC_BULK_IN_ERR_DATA_TOO_LONG = 5u,
+};
+// bult-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
+};
+
+typedef enum {
+  USBTMC_bREQUEST_INITIATE_ABORT_BULK_OUT      = 1u,
+  USBTMC_bREQUEST_CHECK_ABORT_BULK_OUT_STATUS  = 2u,
+  USBTMC_bREQUEST_INITIATE_ABORT_BULK_IN       = 3u,
+  USBTMC_bREQUEST_CHECK_ABORT_BULK_IN_STATUS   = 4u,
+  USBTMC_bREQUEST_INITIATE_CLEAR               = 5u,
+  USBTMC_bREQUEST_CHECK_CLEAR_STATUS           = 6u,
+  USBTMC_bREQUEST_GET_CAPABILITIES             = 7u,
+
+  USBTMC_bREQUEST_INDICATOR_PULSE               = 64u, // Optional
+} usmtmc_request_type_enum;
+
+typedef enum {
+  USBTMC488_bREQUEST_READ_STATUS_BYTE  = 128u,
+  USBTMC488_bREQUEST_REN_CONTROL       = 160u,
+  USBTMC488_bREQUEST_GO_TO_LOCAL       = 161u,
+  USBTMC488_bREQUEST_LOCAL_LOCKOUT     = 162u,
+} usbtmc_request_type_488_enum;
+
+typedef enum {
+  USBTMC_STATUS_SUCCESS = 0x01,
+  USBTMC_STATUS_PENDING = 0x02,
+  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_enum;
+
+/************************************************************
+ * Control Responses
+ */
+
+typedef struct TU_ATTR_PACKED {
+  uint8_t USBTMC_status;                 ///< usbtmc_status_enum
+  uint8_t _reserved;
+  uint16_t bcdUSBTMC;                    ///< USBTMC_VERSION
+
+  struct {
+    uint8_t listenOnly :1;
+    uint8_t talkOnly :1;
+    uint8_t supportsIndicatorPulse :1;
+  } bmIntfcCapabilities;
+  struct {
+    uint8_t canEndBulkInOnTermChar :1;
+  } bmDevCapabilities;
+  uint8_t _reserved2[6];
+  uint8_t _reserved3[12];
+} usbtmc_response_capabilities_t;
+
+TU_VERIFY_STATIC(sizeof(usbtmc_response_capabilities_t) == 0x18, "struct wrong length");
+
+typedef struct TU_ATTR_PACKED
+{
+  uint8_t USBTMC_status;                 ///< usbtmc_status_enum
+  uint8_t _reserved;
+  uint16_t bcdUSBTMC;                    ///< USBTMC_VERSION
+
+  struct
+  {
+    uint8_t listenOnly :1;
+    uint8_t talkOnly :1;
+    uint8_t supportsIndicatorPulse :1;
+  } bmIntfcCapabilities;
+
+  struct
+  {
+    uint8_t canEndBulkInOnTermChar :1;
+  } bmDevCapabilities;
+
+  uint8_t _reserved2[6];
+  uint16_t bcdUSB488;
+
+  struct
+  {
+    uint8_t is488_2 :1;
+    uint8_t supportsREN_GTL_LLO :1;
+    uint8_t supportsTrigger :1;
+  } bmIntfcCapabilities488;
+
+  struct
+  {
+    uint8_t SCPI :1;
+    uint8_t SR1 :1;
+    uint8_t RL1 :1;
+    uint8_t DT1 :1;
+  } bmDevCapabilities488;
+  uint8_t _reserved3[8];
+} usbtmc_response_capabilities_488_t;
+
+TU_VERIFY_STATIC(sizeof(usbtmc_response_capabilities_488_t) == 0x18, "struct wrong length");
+
+typedef struct TU_ATTR_PACKED
+{
+  uint8_t USBTMC_status;
+  uint8_t bTag;
+  uint8_t statusByte;
+} usbtmc_read_stb_rsp_488_t;
+
+TU_VERIFY_STATIC(sizeof(usbtmc_read_stb_rsp_488_t) == 3u, "struct wrong length");
+
+typedef struct TU_ATTR_PACKET
+{
+  union {
+    struct {
+      uint8_t bTag : 7;
+      uint8_t one  : 1;
+    } bNotify1Struct;
+    uint8_t bNotify1;
+  };
+  uint8_t StatusByte;
+} usbtmc_read_stb_interrupt_488_t;
+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
new file mode 100644
index 000000000..4bb21f354
--- /dev/null
+++ b/src/class/usbtmc/usbtmc_device.c
@@ -0,0 +1,420 @@
+/*
+ * usbtmc.c
+ *
+ *  Created on: Sep 9, 2019
+ *      Author: nconrad
+ */
+
+/*
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2019 N Conrad
+ *
+ * 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 file is part of the TinyUSB stack.
+ */
+
+#include "tusb_option.h"
+
+// We don't do any cross-task anything here (everything is in tud or interrupt context).
+// You must ensure thread safety in your own app.
+
+
+//Limitations (not planned to be implemented):
+// "vendor-specific" commands are not handled
+
+// TODO:
+// USBTMC 3.2.2 error conditions not strictly followed
+// No local lock-out, REN, or GTL.
+// Cannot issue clear.
+// No "capabilities" supported
+// Interrupt-IN endpoint
+// 488 MsgID=Trigger
+// Clear message available status byte at the correct time? (488 4.3.1.3)
+// Split transfers
+// No CLEAR_FEATURE/HALT (yet)
+
+#if (TUSB_OPT_DEVICE_ENABLED && CFG_TUD_USBTMC)
+
+#include "usbtmc.h"
+#include "usbtmc_device.h"
+#include "device/dcd.h"
+#include "device/usbd.h"
+
+// FIXME: I shouldn't need to include _pvt headers.
+#include "device/usbd_pvt.h"
+
+typedef enum
+{
+  STATE_IDLE,
+  STATE_RCV,
+  STATE_TX_REQUESTED,
+  STATE_TX_INITIATED
+} usbtmcd_state_enum;
+
+typedef struct
+{
+  usbtmcd_state_enum state;
+  uint8_t itf_id;
+  uint8_t ep_bulk_in;
+  uint8_t ep_bulk_out;
+  uint8_t ep_int_in;
+  uint8_t ep_bulk_in_buf[64];
+  uint8_t ep_bulk_out_buf[64];
+  uint8_t lastTag;
+
+  uint32_t transfer_size_remaining;
+  uint8_t const * devInBuffer;
+} usbtmc_interface_state_t;
+
+static usbtmc_interface_state_t usbtmc_state =
+{
+    .state = STATE_IDLE,
+    .itf_id = 0xFF,
+    .ep_bulk_in = 0,
+    .ep_bulk_out = 0,
+    .ep_int_in = 0
+};
+
+// We want everything to fit nicely in a single packet, so lets require EP size >32
+// I'm not sure if this is really necessary, though.
+TU_VERIFY_STATIC(USBTMCD_MAX_PACKET_SIZE >= 32u,"USBTMC dev EP packet size too small");
+
+// called from app
+// We keep a reference to the buffer, so it MUST not change until the app is
+// notified that the transfer is complete.
+// length of data is specified in the hdr.
+bool usbtmcd_transmit_dev_msg_data(
+    uint8_t rhport,
+    usbtmc_msg_dev_dep_msg_in_header_t const * hdr,
+    const void *data)
+{
+  TU_ASSERT(usbtmc_state.state == STATE_TX_REQUESTED);
+  TU_ASSERT(hdr->TransferSize > 0u);
+
+  // Copy in the header
+  memcpy(usbtmc_state.ep_bulk_in_buf, hdr, sizeof(*hdr));
+  uint packetLen = sizeof(*hdr);
+  // Single-packet transfer
+  if((packetLen + hdr->TransferSize) <= USBTMCD_MAX_PACKET_SIZE)
+  {
+    memcpy((uint8_t*)(usbtmc_state.ep_bulk_in_buf) + packetLen, data, hdr->TransferSize);
+    packetLen = (uint16_t)(packetLen+ hdr->TransferSize);
+    // Pad up to multiple of 4 bytes
+    while((packetLen % 4) != 0)
+    {
+      usbtmc_state.ep_bulk_in_buf[packetLen] = 0;
+      packetLen++;
+    }
+    usbtmc_state.transfer_size_remaining = 0;
+    usbtmc_state.devInBuffer = NULL;
+  }
+  else
+  {
+    memcpy((uint8_t*)(usbtmc_state.ep_bulk_in_buf) + packetLen, data, USBTMCD_MAX_PACKET_SIZE - packetLen);
+    usbtmc_state.transfer_size_remaining = hdr->TransferSize - (USBTMCD_MAX_PACKET_SIZE - packetLen);
+    usbtmc_state.devInBuffer += (USBTMCD_MAX_PACKET_SIZE - packetLen);
+    packetLen = USBTMCD_MAX_PACKET_SIZE;
+  }
+  usbtmc_state.state = STATE_TX_INITIATED;
+  TU_VERIFY( usbd_edpt_xfer(rhport, usbtmc_state.ep_bulk_in, usbtmc_state.ep_bulk_in_buf,(uint16_t)packetLen));
+  return true;
+}
+
+void usbtmcd_init(void)
+{
+
+}
+
+bool usbtmcd_open(uint8_t rhport, tusb_desc_interface_t const * itf_desc, uint16_t *p_length)
+{
+  (void)rhport;
+  uint8_t const * p_desc;
+  uint8_t found_endpoints = 0;
+
+  // Perhaps there are other application specific class drivers, so don't assert here.
+  if( itf_desc->bInterfaceClass != USBTMC_APP_CLASS)
+    return false;
+  if( itf_desc->bInterfaceSubClass != USBTMC_APP_SUBCLASS)
+    return false;
+
+  // Only 2 or 3 endpoints are allowed for USBTMC.
+  TU_ASSERT((itf_desc->bNumEndpoints == 2) || (itf_desc->bNumEndpoints ==3));
+
+  // Interface
+  (*p_length) = 0u;
+  p_desc = (uint8_t const *) itf_desc;
+
+  usbtmc_state.itf_id = itf_desc->bInterfaceNumber;
+
+  while (found_endpoints < itf_desc->bNumEndpoints)
+  {
+    if ( TUSB_DESC_ENDPOINT == p_desc[DESC_OFFSET_TYPE])
+    {
+      tusb_desc_endpoint_t const *ep_desc = (tusb_desc_endpoint_t const *)p_desc;
+      switch(ep_desc->bmAttributes.xfer) {
+        case TUSB_XFER_BULK:
+          if (tu_edpt_dir(ep_desc->bEndpointAddress) == TUSB_DIR_IN)
+          {
+            usbtmc_state.ep_bulk_in = ep_desc->bEndpointAddress;
+          } else {
+            usbtmc_state.ep_bulk_out = ep_desc->bEndpointAddress;
+          }
+
+          break;
+        case TUSB_XFER_INTERRUPT:
+          TU_ASSERT(tu_edpt_dir(ep_desc->bEndpointAddress) == TUSB_DIR_IN);
+          TU_ASSERT(usbtmc_state.ep_int_in == 0);
+          usbtmc_state.ep_int_in = ep_desc->bEndpointAddress;
+          break;
+        default:
+          TU_ASSERT(false);
+      }
+      TU_VERIFY( dcd_edpt_open(rhport, ep_desc));
+      found_endpoints++;
+    }
+    (*p_length) = (uint8_t)((*p_length) + p_desc[DESC_OFFSET_LEN]);
+    p_desc = tu_desc_next(p_desc);
+  }
+
+  // bulk endpoints are required, but interrupt IN is optional
+  TU_ASSERT(usbtmc_state.ep_bulk_in != 0);
+  TU_ASSERT(usbtmc_state.ep_bulk_out != 0);
+  if (itf_desc->bNumEndpoints == 2) {
+    TU_ASSERT(usbtmc_state.ep_int_in == 0);
+  }
+  else if (itf_desc->bNumEndpoints == 2)
+  {
+    TU_ASSERT(usbtmc_state.ep_int_in != 0);
+  }
+  TU_VERIFY( usbd_edpt_xfer(rhport, usbtmc_state.ep_bulk_out, usbtmc_state.ep_bulk_out_buf, 64));
+
+  return true;
+}
+void usbtmcd_reset(uint8_t rhport)
+{
+  // FIXME: Do endpoints need to be closed here?
+  (void)rhport;
+}
+static bool handle_devMsgOut(uint8_t rhport, void *data, size_t len)
+{
+  (void)rhport;
+  bool shortPacket = (len < USBTMCD_MAX_PACKET_SIZE);
+  if(usbtmc_state.state == STATE_IDLE)
+  {
+    // must be a header, should have been confirmed before calling here.
+    usbtmc_msg_request_dev_dep_out *msg = (usbtmc_msg_request_dev_dep_out*)data;
+    usbtmc_state.transfer_size_remaining = msg->TransferSize;
+    TU_VERIFY(usbtmcd_app_msgBulkOut_start(msg));
+    len -= sizeof(*msg);
+    data = (uint8_t*)data + sizeof(*msg);
+  }
+  // Packet is to be considered complete when we get enough data or at a short packet.
+  bool atEnd = false;
+  if(len >= usbtmc_state.transfer_size_remaining || shortPacket)
+    atEnd = true;
+  if(len > usbtmc_state.transfer_size_remaining)
+    len = usbtmc_state.transfer_size_remaining;
+  usbtmcd_app_msg_data(data, len, atEnd);
+  if(atEnd)
+    usbtmc_state.state = STATE_IDLE;
+  else
+    usbtmc_state.state = STATE_RCV;
+  return true;
+}
+static bool handle_devMsgIn(uint8_t rhport, void *data, size_t len)
+{
+  TU_VERIFY(len == sizeof(usbtmc_msg_request_dev_dep_in));
+  usbtmc_msg_request_dev_dep_in *msg = (usbtmc_msg_request_dev_dep_in*)data;
+  TU_VERIFY(usbtmc_state.state == STATE_IDLE);
+  usbtmc_state.state = STATE_TX_REQUESTED;
+  usbtmc_state.transfer_size_remaining = msg->TransferSize;
+  TU_VERIFY(usbtmcd_app_msgBulkIn_request(rhport, msg));
+  return true;
+}
+
+bool usbtmcd_xfer_cb(uint8_t rhport, uint8_t ep_addr, xfer_result_t result, uint32_t xferred_bytes)
+{
+  TU_VERIFY(result == XFER_RESULT_SUCCESS);
+  if(ep_addr == usbtmc_state.ep_bulk_out)
+  {
+    switch(usbtmc_state.state)
+    {
+    case STATE_IDLE:
+      TU_VERIFY(xferred_bytes >= sizeof(usbtmc_msg_generic_t));
+      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);
+      usbtmc_state.lastTag = msg->header.bTag;
+
+      switch(msg->header.MsgID) {
+      case USBTMC_MSGID_DEV_DEP_MSG_OUT:
+        TU_VERIFY(handle_devMsgOut(rhport, msg, xferred_bytes));
+        TU_VERIFY(usbd_edpt_xfer(rhport, usbtmc_state.ep_bulk_out, usbtmc_state.ep_bulk_out_buf, 64));
+        break;
+      case USBTMC_MSGID_DEV_DEP_MSG_IN:
+        TU_VERIFY(handle_devMsgIn(rhport, msg, xferred_bytes));
+        break;
+      case USBTMC_MSGID_VENDOR_SPECIFIC_MSG_OUT:
+      case USBTMC_MSGID_VENDOR_SPECIFIC_IN:
+      case USBTMC_MSGID_USB488_TRIGGER:
+      default:
+        TU_VERIFY(false);
+      }
+      return true;
+
+    case STATE_RCV:
+      TU_VERIFY(handle_devMsgOut(rhport, usbtmc_state.ep_bulk_out_buf, xferred_bytes));
+      TU_VERIFY( usbd_edpt_xfer(rhport, usbtmc_state.ep_bulk_out, usbtmc_state.ep_bulk_out_buf, 64));
+      return true;
+      break;
+
+    default:
+      TU_VERIFY(false);
+    }
+  }
+  else if(ep_addr == usbtmc_state.ep_bulk_in)
+  {
+    TU_ASSERT(usbtmc_state.state == STATE_TX_INITIATED);
+    if(usbtmc_state.transfer_size_remaining == 0)
+    {
+      usbtmc_state.state = STATE_IDLE;
+      TU_VERIFY(usbtmcd_app_msgBulkIn_complete(rhport));
+      TU_VERIFY( usbd_edpt_xfer(rhport, usbtmc_state.ep_bulk_out, usbtmc_state.ep_bulk_out_buf, 64));
+    }
+    else if(usbtmc_state.transfer_size_remaining >= USBTMCD_MAX_PACKET_SIZE)
+    {
+      memcpy(usbtmc_state.ep_bulk_in_buf, usbtmc_state.devInBuffer, USBTMCD_MAX_PACKET_SIZE);
+      usbtmc_state.devInBuffer += USBTMCD_MAX_PACKET_SIZE;
+      usbtmc_state.transfer_size_remaining -= USBTMCD_MAX_PACKET_SIZE;
+      TU_VERIFY( usbd_edpt_xfer(rhport, usbtmc_state.ep_bulk_in, usbtmc_state.ep_bulk_in_buf,USBTMCD_MAX_PACKET_SIZE));
+    }
+    else // short packet
+    {
+      uint packetLen = usbtmc_state.transfer_size_remaining;
+      memcpy(usbtmc_state.ep_bulk_in_buf, usbtmc_state.devInBuffer, usbtmc_state.transfer_size_remaining);
+      while((packetLen % 4) != 0)
+      {
+        usbtmc_state.ep_bulk_in_buf[packetLen] = 0;
+        packetLen++;
+      }
+      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));
+    }
+    return true;
+  }
+  else if (ep_addr == usbtmc_state.ep_int_in) {
+    // Good?
+    return true;
+  }
+  return false;
+}
+
+bool usbtmcd_control_request(uint8_t rhport, tusb_control_request_t const * request) {
+
+#if (USBTMC_CFG_ENABLE_488)
+  ushort bTag;
+#endif
+  // We only handle class requests.
+  if(request->bmRequestType_bit.type != TUSB_REQ_TYPE_CLASS)
+    return false;
+
+  switch(request->bRequest)
+  {
+  // USBTMC required requests
+  case USBTMC_bREQUEST_INITIATE_ABORT_BULK_OUT:
+  case USBTMC_bREQUEST_CHECK_ABORT_BULK_OUT_STATUS:
+  case USBTMC_bREQUEST_INITIATE_ABORT_BULK_IN:
+  case USBTMC_bREQUEST_CHECK_ABORT_BULK_IN_STATUS:
+  case USBTMC_bREQUEST_INITIATE_CLEAR:
+  case USBTMC_bREQUEST_CHECK_CLEAR_STATUS:
+    TU_VERIFY(false);
+    break;
+
+  case USBTMC_bREQUEST_GET_CAPABILITIES:
+    TU_VERIFY(request->bmRequestType == 0xA1);
+    TU_VERIFY(request->wValue == 0x0000);
+    TU_VERIFY(request->wIndex == usbtmc_state.itf_id);
+    TU_VERIFY(request->wLength == sizeof(usbtmcd_app_capabilities));
+    TU_VERIFY(tud_control_xfer(rhport, request, (void*)&usbtmcd_app_capabilities, sizeof(usbtmcd_app_capabilities)));
+    return true;
+  // USBTMC Optional Requests
+  case USBTMC_bREQUEST_INDICATOR_PULSE: // Optional
+    TU_VERIFY(false);
+    return false;
+
+#if (USBTMC_CFG_ENABLE_488)
+    // USB488 required requests
+  case USBTMC488_bREQUEST_READ_STATUS_BYTE:
+
+    bTag = request->wValue & 0x7F;
+    TU_VERIFY(request->bmRequestType == 0xA1);
+    TU_VERIFY((request->wValue & (~0x7F)) == 0u); // Other bits are required to be zero
+    TU_VERIFY(bTag >= 0x02 && bTag <= 127);
+    TU_VERIFY(request->wIndex == usbtmc_state.itf_id);
+    TU_VERIFY(request->wLength == 0x0003);
+    usbtmc_read_stb_rsp_488_t rsp;
+    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 =
+      {
+          .bNotify1   = (uint8_t)(0x80 | bTag),
+          .StatusByte = usbtmcd_app_get_stb(rhport, &(rsp.USBTMC_status))
+      };
+      usbd_edpt_xfer(rhport, usbtmc_state.ep_int_in, (void*)&intMsg,sizeof(intMsg));
+
+    }
+    else
+    {
+      rsp.statusByte = usbtmcd_app_get_stb(rhport, &(rsp.USBTMC_status));
+    }
+    TU_VERIFY(tud_control_xfer(rhport, request, (void*)&rsp, sizeof(rsp)));
+    return true;
+
+    // USB488 optional requests
+  case USBTMC488_bREQUEST_REN_CONTROL:
+  case USBTMC488_bREQUEST_GO_TO_LOCAL:
+  case USBTMC488_bREQUEST_LOCAL_LOCKOUT:
+    TU_VERIFY(false);
+    return false;
+#endif
+
+  default:
+    TU_VERIFY(false);
+  }
+  TU_VERIFY(false);
+}
+
+bool usbtmcd_control_complete(uint8_t rhport, tusb_control_request_t const * request)
+{
+  (void)rhport;
+  //------------- Class Specific Request -------------//
+  TU_VERIFY (request->bmRequestType_bit.type == TUSB_REQ_TYPE_CLASS);
+
+  return true;
+}
+
+#endif /* CFG_TUD_TSMC */
diff --git a/src/class/usbtmc/usbtmc_device.h b/src/class/usbtmc/usbtmc_device.h
new file mode 100644
index 000000000..c03ca9461
--- /dev/null
+++ b/src/class/usbtmc/usbtmc_device.h
@@ -0,0 +1,130 @@
+/*
+ * usbtmc_device.h
+ *
+ *  Created on: Sep 10, 2019
+ *      Author: nconrad
+ */
+/*
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2019 N Conrad
+ *
+ * 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 file is part of the TinyUSB stack.
+ */
+
+
+#ifndef CLASS_USBTMC_USBTMC_DEVICE_H_
+#define CLASS_USBTMC_USBTMC_DEVICE_H_
+
+#include "usbtmc.h"
+
+// Enable 488 mode by default
+#if !defined(USBTMC_CFG_ENABLE_488)
+#define USBTMC_CFG_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
+ */
+
+#if (USBTMC_CFG_ENABLE_488)
+extern usbtmc_response_capabilities_488_t const usbtmcd_app_capabilities;
+#else
+extern usbtmc_response_capabilities_t const usbtmcd_app_capabilities;
+#endif
+
+bool usbtmcd_app_msgBulkOut_start(usbtmc_msg_request_dev_dep_out const * msgHeader);
+
+// transfer_complete does not imply that a message is complete.
+bool usbtmcd_app_msg_data(void *data, size_t len, bool transfer_complete);
+
+bool usbtmcd_app_msgBulkIn_request(uint8_t rhport, usbtmc_msg_request_dev_dep_in const * request);
+
+bool usbtmcd_app_msgBulkIn_complete(uint8_t rhport);
+
+#if (USBTMC_CFG_ENABLE_488)
+uint8_t usbtmcd_app_get_stb(uint8_t rhport, uint8_t *rspResult);
+
+//TU_ATTR_WEAK bool usbtmcd_app_go_to_local(uint8_t rhport);
+#endif
+
+/*******************************************
+ * Called from app
+ *
+ * We keep a reference to the buffer, so it MUST not change until the app is
+ * notified that the transfer is complete.
+ ******************************************/
+
+bool usbtmcd_transmit_dev_msg_data(
+    uint8_t rhport,
+    usbtmc_msg_dev_dep_msg_in_header_t const * hdr,
+    const void *data);
+
+
+/* "callbacks" from USB device core */
+
+bool usbtmcd_open(uint8_t rhport, tusb_desc_interface_t const * itf_desc, uint16_t *p_length);
+void usbtmcd_reset(uint8_t rhport);
+bool usbtmcd_xfer_cb(uint8_t rhport, uint8_t ep_addr, xfer_result_t result, uint32_t xferred_bytes);
+bool usbtmcd_control_request(uint8_t rhport, tusb_control_request_t const * request);
+bool usbtmcd_control_complete(uint8_t rhport, tusb_control_request_t const * request);
+void usbtmcd_init(void);
+
+/************************************************************
+ * USBTMC Descriptor Templates
+ *************************************************************/
+
+#define USBTMC_APP_CLASS    TUSB_CLASS_APPLICATION_SPECIFIC
+#define USBTMC_APP_SUBCLASS 0x03
+
+#define USBTMC_PROTOCOL_STD    0x00
+#define USBTMC_PROTOCOL_USB488 0x01
+
+//   Interface number, number of endpoints, EP string index, USB_TMC_PROTOCOL*, bulk-out endpoint ID,
+//   bulk-in endpoint ID
+#define USBTMC_IF_DESCRIPTOR(_itfnum, _bNumEndpoints, _stridx, _itfProtocol) \
+/* Interface */ \
+  0x09, TUSB_DESC_INTERFACE, _itfnum, 0x00, _bNumEndpoints, USBTMC_APP_CLASS, USBTMC_APP_SUBCLASS, _itfProtocol, _stridx
+
+#define USBTMC_IF_DESCRIPTOR_LEN 9u
+
+// bulk-out Size must be a multiple of 4 bytes
+#define USBTMC_BULK_DESCRIPTORS(_epout, _epin) \
+/* Endpoint Out */ \
+7, TUSB_DESC_ENDPOINT, _epout, TUSB_XFER_BULK, U16_TO_U8S_LE(USBTMCD_MAX_PACKET_SIZE), 0u, \
+/* Endpoint In */ \
+7, TUSB_DESC_ENDPOINT, _epin, TUSB_XFER_BULK, U16_TO_U8S_LE(USBTMCD_MAX_PACKET_SIZE), 0u
+
+#define USBTMC_BULK_DESCRIPTORS_LEN (7u+7u)
+
+/* optional interrupt endpoint */ \
+// _int_pollingInterval : for LS/FS, expressed in frames (1ms each). 16 may be a good number?
+#define USBTMC_INT_DESCRIPTOR(_ep_interrupt, _ep_interrupt_size, _int_pollingInterval ) \
+7, TUSB_DESC_ENDPOINT, _ep_interrupt, TUSB_XFER_INTERRUPT, U16_TO_U8S_LE(_ep_interrupt_size), 0x16
+
+#define USBTMC_INT_DESCRIPTOR_LEN (7u)
+
+
+#endif /* CLASS_USBTMC_USBTMC_DEVICE_H_ */
diff --git a/src/device/usbd.c b/src/device/usbd.c
index c92884334..572708f7d 100644
--- a/src/device/usbd.c
+++ b/src/device/usbd.c
@@ -145,6 +145,22 @@ static usbd_class_driver_t const usbd_class_drivers[] =
       .sof              = NULL

   },

   #endif

+

+  #if CFG_TUD_USBTMC

+  // Presently USBTMC is the only defined class with the APP_SPECIFIC class code.

+  // We maybe need to add subclass codes here, or a callback to ask if a driver can

+  // handle a particular interface.

+  {

+      .class_code       = TUSB_CLASS_APPLICATION_SPECIFIC,

+      .init             = usbtmcd_init,

+      .reset            = usbtmcd_reset,

+      .open             = usbtmcd_open,

+      .control_request  = usbtmcd_control_request,

+      .control_complete = usbtmcd_control_complete,

+      .xfer_cb          = usbtmcd_xfer_cb,

+      .sof              = NULL

+  },

+  #endif

 };

 

 enum { USBD_CLASS_DRIVER_COUNT = TU_ARRAY_SIZE(usbd_class_drivers) };

diff --git a/src/tusb.h b/src/tusb.h
index fe8673726..1a6ff0b10 100644
--- a/src/tusb.h
+++ b/src/tusb.h
@@ -83,6 +83,10 @@
   #if CFG_TUD_VENDOR

     #include "class/vendor/vendor_device.h"

   #endif

+

+  #if CFG_TUD_USBTMC

+    #include "class/usbtmc/usbtmc_device.h"

+  #endif

 #endif

 

 

diff --git a/src/tusb_option.h b/src/tusb_option.h
index 9aacb558f..76ea59758 100644
--- a/src/tusb_option.h
+++ b/src/tusb_option.h
@@ -181,6 +181,10 @@
   #define CFG_TUD_VENDOR          0

 #endif

 

+#ifndef CFG_TUD_USBTMC

+  #define CFG_TUD_USBTMC          0

+#endif

+

 

 //--------------------------------------------------------------------

 // HOST OPTIONS