usb_descriptors.c

#include "tusb.h"

// String Descriptor Index
enum
{
  STRID_LANGID = 0,
  STRID_PRODUCT,
  STRID_MANUFACTURER,
  STRID_SERIAL,
};

//--------------------------------------------------------------------+
// Device Descriptors
//--------------------------------------------------------------------+
tusb_desc_device_t const desc_device =
{
    .bLength            = sizeof(tusb_desc_device_t),
    .bDescriptorType    = TUSB_DESC_DEVICE,
    .bcdUSB             = 0x0110,
    .bDeviceClass       = 0x00,
    .bDeviceSubClass    = 0x00,
    .bDeviceProtocol    = 0x00,
    .bMaxPacketSize0    = CFG_TUD_ENDPOINT0_SIZE,

    /* using Dapper Miser CMSIS-DAP VID:PID */
    .idVendor           = 0x1209,
    .idProduct          = 0x2488,
    .bcdDevice          = 0x1005,

    .iManufacturer      = STRID_MANUFACTURER,
    .iProduct           = STRID_PRODUCT,
    .iSerialNumber      = STRID_SERIAL,

    .bNumConfigurations = 0x01
};

// Invoked when received GET DEVICE DESCRIPTOR
// Application return pointer to descriptor
uint8_t const * tud_descriptor_device_cb(void)
{
  return (uint8_t const *) &desc_device;
}

//--------------------------------------------------------------------+
// HID Report Descriptor
//--------------------------------------------------------------------+

static uint8_t const desc_hid_report[] =
{
  TUD_HID_REPORT_DESC_GENERIC_INOUT(CFG_TUD_HID_EP_BUFSIZE)
};

// Invoked when received GET HID REPORT DESCRIPTOR
// Application return pointer to descriptor
// Descriptor contents must exist long enough for transfer to complete
uint8_t const * tud_hid_descriptor_report_cb(uint8_t instance)
{
  (void)instance;
  return desc_hid_report;
}

//--------------------------------------------------------------------+
// Configuration Descriptor
//--------------------------------------------------------------------+

enum
{
  ITF_NUM_HID,
  ITF_NUM_TOTAL
};

#define  CONFIG_TOTAL_LEN  (TUD_CONFIG_DESC_LEN + TUD_HID_INOUT_DESC_LEN)

#define EPNUM_HID   0x01

uint8_t const desc_configuration[] =
{
  // Config number, interface count, string index, total length, attribute, power in mA
  TUD_CONFIG_DESCRIPTOR(1, ITF_NUM_TOTAL, 0, CONFIG_TOTAL_LEN, TUSB_DESC_CONFIG_ATT_REMOTE_WAKEUP, 100),

  // Interface number, string index, protocol, report descriptor len, EP In & Out address, size & polling interval
  TUD_HID_INOUT_DESCRIPTOR(ITF_NUM_HID, 0, HID_PROTOCOL_REPORT, sizeof(desc_hid_report), EPNUM_HID, 0x80 | EPNUM_HID, CFG_TUD_HID_EP_BUFSIZE, 1)
};

// Invoked when received GET CONFIGURATION DESCRIPTOR
// Application return pointer to descriptor
// Descriptor contents must exist long enough for transfer to complete
uint8_t const * tud_descriptor_configuration_cb(uint8_t index)
{
  (void) index; // for multiple configurations
  return desc_configuration;
}

//--------------------------------------------------------------------+
// String Descriptors
//--------------------------------------------------------------------+

char unique_id[17] = "0000000000000000";

// array of pointer to string descriptors
char const* string_desc_arr [] =
{
  [STRID_LANGID]       = (const char[]) { 0x09, 0x04 }, // supported language is English (0x0409)
  [STRID_PRODUCT]      = "CMSIS-DAP",                   // Product
  [STRID_MANUFACTURER] = "pico-debug",                  // Manufacturer
  [STRID_SERIAL]       = (const char *)unique_id,       // Serial
};

static uint16_t _desc_str[32];

// Invoked when received GET STRING DESCRIPTOR request
// Application return pointer to descriptor, whose contents must exist long enough for transfer to complete
uint16_t const* tud_descriptor_string_cb(uint8_t index, uint16_t langid)
{
  (void) langid;

  uint8_t chr_count;

  if ( index == 0)
  {
    memcpy(&_desc_str[1], string_desc_arr[0], 2);
    chr_count = 1;
  }else
  {
    // Note: the 0xEE index string is a Microsoft OS 1.0 Descriptors.
    // https://docs.microsoft.com/en-us/windows-hardware/drivers/usbcon/microsoft-defined-usb-descriptors

    if ( !(index < sizeof(string_desc_arr)/sizeof(string_desc_arr[0])) ) return NULL;

    const char* str = string_desc_arr[index];

    // Cap at max char
    chr_count = strlen(str);
    if ( chr_count > 31 ) chr_count = 31;

    // Convert ASCII string into UTF-16
    for(uint8_t i=0; i<chr_count; i++)
    {
      _desc_str[1+i] = str[i];
    }
  }

  // first byte is length (including header), second byte is string type
  _desc_str[0] = (TUSB_DESC_STRING << 8 ) | (2*chr_count + 2);

  return _desc_str;
}