调试USB例题需要用到2个上位机程序：

PC端HID交互程序，提供了VC源程序。

图形方式的按钮输入、LED输出操作：

总线扑捉器：

main程序初始化部分很简单：

/* Initialize USB */
USBD_Init(&USB_Device_dev,
&USR_desc,
&USBD_HID_cb,
&USR_cb);

打开 usbd_custom_hid_core.c

这个数据结构是用户关心的

USBD_Class_cb_TypeDef USBD_HID_cb =
{
USBD_HID_Init,
USBD_HID_DeInit,
USBD_HID_Setup,
NULL, /*EP0_TxSent*/
USBD_HID_EP0_RxReady, /*EP0_RxReady*/ /* STATUS STAGE IN */
USBD_HID_DataIn, /*DataIn*/                  输入输出调用程序
USBD_HID_DataOut, /*DataOut*/
NULL, /*SOF */
USBD_HID_GetCfgDesc,
};

USB接收数据处理：

打开 usbd_custom_hid_core.c

找到这个程序，可以看出根据上位机发来的数据参数，分别点亮不同的LED

/**
* @brief USBD_HID_DataOut
* handle data IN Stage
* @param pdev: device instance
* @param epnum: endpoint index
* @retval status
*/
uint8_t USBD_HID_DataOut (void *pdev,
uint8_t epnum)
{
BitAction Led_State;
if (epnum == 1)
{
if (Report_buf[1] == 0)
{
Led_State = Bit_RESET;
}
else
{
Led_State = Bit_SET;
}
switch (Report_buf[0])
{
case 1: /* Led 3 */
if (Led_State != Bit_RESET)
{
STM_EVAL_LEDOn(LED3);
}
else
{
STM_EVAL_LEDOff(LED3);
}
break;
case 2: /* Led 4 */
if (Led_State != Bit_RESET)
{
STM_EVAL_LEDOn(LED4);
}
else
{
STM_EVAL_LEDOff(LED4);
}
break;
case 3: /* Led 5 */
if (Led_State != Bit_RESET)
{
STM_EVAL_LEDOn(LED5);
}
else
{
STM_EVAL_LEDOff(LED5);
}
break;
case 4: /* Led 6 */
if (Led_State != Bit_RESET)
{
STM_EVAL_LEDOn(LED6);
}
else
{
STM_EVAL_LEDOff(LED6);
}
break;
default:
STM_EVAL_LEDOff(LED3);
STM_EVAL_LEDOff(LED4);
STM_EVAL_LEDOff(LED5);
STM_EVAL_LEDOff(LED6);
break;
}
}
DCD_EP_PrepareRx(pdev,HID_IN_EP,Report_buf,2);
return USBD_OK;
}

STM32F072B-DISCO 深入研究 USB系统