usb端点(endpoint)知识详解

stsw-stm32121库中：

把数据copy到对应端点的发送缓冲区后，使能发送状态编码STAT_TX=VALID，这时候usb的该端点就可以发送数据了

----->即先调用usb_sil.c中的USB_SIL_Write()，然后调用SetEPRxValid(uint8_t bEpNum)函数。

或者STM32Cube中库文件stm32f1xx_ii_usb.c:中函数USB_WritePMA(),然后调用PCD_SET_EP_TX_STATUS(USBx, ep->num, USB_EP_TX_VALID);函数

/**
  * @brief  Copy a buffer from user memory area to packet memory area (PMA)
  * @param  USBx : pointer to USB register.
  * @param  pbUsrBuf : pointer to user memory area.
  * @param  wPMABufAddr : address into PMA.
  * @param  wNBytes : number of bytes to be copied.
  * @retval None
  */
void USB_WritePMA(USB_TypeDef *USBx, uint8_t *pbUsrBuf, uint16_t wPMABufAddr, uint16_t wNBytes)
{
  uint32_t nbytes = (wNBytes + 1) >> 1;   /* nbytes = (wNBytes + 1) / 2 */
  uint32_t index = 0, temp1 = 0, temp2 = 0;
  uint16_t *pdwVal = NULL;

  pdwVal = (uint16_t *)(wPMABufAddr * 2 + (uint32_t)USBx + 0x400);
  for (index = nbytes; index != 0; index--)
  {
    temp1 = (uint16_t) * pbUsrBuf;
    pbUsrBuf++;
    temp2 = temp1 | (uint16_t) * pbUsrBuf << 8;
    *pdwVal++ = temp2;
    pdwVal++;
    pbUsrBuf++;
  }
}

　　

/**
  * @brief  Copy a buffer from  packet memory area (PMA) to user memory area
  * @param  USBx : pointer to USB register.
* @param  pbUsrBuf : pointer to user memory area.
  * @param  wPMABufAddr : address into PMA.
  * @param  wNBytes : number of bytes to be copied.
  * @retval None
  */
void USB_ReadPMA(USB_TypeDef *USBx, uint8_t *pbUsrBuf, uint16_t wPMABufAddr, uint16_t wNBytes)
{
  uint32_t nbytes = (wNBytes + 1) >> 1;/* /2*/
  uint32_t index = 0;
  uint32_t *pdwVal = NULL;

  pdwVal = (uint32_t *)(wPMABufAddr * 2 + (uint32_t)USBx + 0x400);
  for (index = nbytes; index != 0; index--)
  {
    *(uint16_t*)pbUsrBuf++ = *pdwVal++;
    pbUsrBuf++;
  }
}

stm32cube中定义的端点属性结构体

typedef struct
{
  uint8_t   num;            /*!< Endpoint number
                                This parameter must be a number between Min_Data = 1 and Max_Data = 15    */

  uint8_t   is_in;          /*!< Endpoint direction
                                This parameter must be a number between Min_Data = 0 and Max_Data = 1     */

  uint8_t   is_stall;       /*!< Endpoint stall condition
                                This parameter must be a number between Min_Data = 0 and Max_Data = 1     */

  uint8_t   type;           /*!< Endpoint type
                                 This parameter can be any value of @ref USB_EP_Type                      */

  uint16_t  pmaadress;      /*!< PMA Address
                                 This parameter can be any value between Min_addr = 0 and Max_addr = 1K   */

  uint16_t  pmaaddr0;       /*!< PMA Address0
                                 This parameter can be any value between Min_addr = 0 and Max_addr = 1K   */

  uint16_t  pmaaddr1;        /*!< PMA Address1
                                 This parameter can be any value between Min_addr = 0 and Max_addr = 1K   */

  uint8_t   doublebuffer;    /*!< Double buffer enable
                                 This parameter can be 0 or 1                                             */

  uint16_t  tx_fifo_num;    /*!< This parameter is not required by USB Device FS peripheral, it is used
                                 only by USB OTG FS peripheral
                                 This parameter is added to ensure compatibility across USB peripherals   */

  uint32_t  maxpacket;      /*!< Endpoint Max packet size
                                 This parameter must be a number between Min_Data = 0 and Max_Data = 64KB */

  uint8_t   *xfer_buff;     /*!< Pointer to transfer buffer                                               */

  uint32_t  xfer_len;       /*!< Current transfer length                                                  */

  uint32_t  xfer_count;     /*!< Partial transfer length in case of multi packet transfer                 */

} USB_EPTypeDef;

　F103中usb的最大数据分组为1023个字节（每个端点的PMA最大是1023）