message: Adapt the USB serial number to match the one displayed by the STM in bootloader mode
diff: #include "usbd_core.h"
  #include "usbd_desc.h"
  #include "usbd_conf.h"
  +#include "utils.h"
  /** @addtogroup STM32_USB_OTG_DEVICE_LIBRARY
  * @{
  #define USBD_PRODUCT_XSTR(s) USBD_PRODUCT_STR(s)
  #define USBD_PRODUCT_STR(s) #s
  #define USBD_PRODUCT_STRING_FS ODrive version HW_VERSION_MAJOR.HW_VERSION_MINOR
  -#define USBD_SERIALNUMBER_STRING_FS "000000000001"
  #define USBD_CONFIGURATION_STRING_FS "CDC Config"
  #define USBD_INTERFACE_STRING_FS "CDC Interface"
  @@ -286,14 +286,25 @@ uint8_t * USBD_FS_ManufacturerStrDescriptor( USBD_SpeedTypeDef speed , uint16_t
  */
  uint8_t * USBD_FS_SerialStrDescriptor( USBD_SpeedTypeDef speed , uint16_t *length)
  {
  - if(speed == USBD_SPEED_HIGH)
  - {
  - USBD_GetString ((uint8_t *)USBD_SERIALNUMBER_STRING_FS, USBD_StrDesc, length);
  + // This procedure of building a USB serial number should be identical
  + // to the way the STM's built-in USB bootloader does it. This means
  + // that the device will have the same serial number in normal and DFU mode.
  + uint32_t uuid0 = *(uint32_t *) (ID_UNIQUE_ADDRESS + 0);
  + uint32_t uuid1 = *(uint32_t *) (ID_UNIQUE_ADDRESS + 4);
  + uint32_t uuid2 = *(uint32_t *) (ID_UNIQUE_ADDRESS + 8);
  + uint32_t uuid_first_part = uuid0 + uuid2;
  + uint8_t str[13];
  + for (size_t i = 0; i < 8; ++i) {
  + str[i] = "0123456789ABCDEF"[(uuid_first_part >> 28) & 0xf];
  + uuid_first_part <<= 4;
  }
  - else
  - {
  - USBD_GetString ((uint8_t *)USBD_SERIALNUMBER_STRING_FS, USBD_StrDesc, length);
  + for (size_t i = 8; i < 12; ++i) {
  + str[i] = "0123456789ABCDEF"[(uuid1 >> 28) & 0xf];
  + uuid1 <<= 4;
  }
  + str[12] = 0;
  +
  + USBD_GetString ((uint8_t *)str, USBD_StrDesc, length);
  return USBD_StrDesc;
  }
  