1 STM32F1兩個USB中斷入口

STM32中斷入口有兩個，分別是USB_HP_CAN1_TX_IRQHandler和USB_LP_CAN1_RX0_IRQHandler。

其中USB_Istr函數調用了CTR_LP函數，代碼如下。

/*******************************************************************************
* Function Name  : USB_HP_CAN1_TX_IRQHandler
* Description    : This function handles USB High Priority or CAN TX interrupts
*                  requests.
* Input          : None
* Output         : None
* Return         : None
*******************************************************************************/
void USB_HP_CAN1_TX_IRQHandler(void)
{
  CTR_HP();
}

/*******************************************************************************
* Function Name  : USB_LP_CAN1_RX0_IRQHandler
* Description    : This function handles USB Low Priority or CAN RX0 interrupts
*                  requests.
* Input          : None
* Output         : None
* Return         : None
*******************************************************************************/
void USB_LP_CAN1_RX0_IRQHandler(void)
{
  USB_Istr();
}

2 CTR_LP

CTR_LP為低優先級端點傳輸正常時的中斷服務函數，控制傳輸只能在CTR_LP里面處理，代碼如下。

/*******************************************************************************
* Function Name  : CTR_LP.
* Description    : Low priority Endpoint Correct Transfer interrupt's service
*                  routine.
* Input          : None.
* Output         : None.
* Return         : None.
*******************************************************************************/
void CTR_LP(void)
{
  uint32_t wEPVal = 0;
  /* stay in loop while pending ints */
  while (((wIstr = _GetISTR()) & ISTR_CTR) != 0)
  {
    _SetISTR((uint16_t)CLR_CTR); /* clear CTR flag */
    /* extract highest priority endpoint number */
    EPindex = (uint8_t)(wIstr & ISTR_EP_ID);
    if (EPindex == 0)
    {
      /* Decode and service control endpoint interrupt */
      /* calling related service routine */
      /* (Setup0_Process, In0_Process, Out0_Process) */

      /* save RX & TX status */
      /* and set both to NAK */
      SaveRState = _GetEPRxStatus(ENDP0);
      SaveTState = _GetEPTxStatus(ENDP0);
      _SetEPRxStatus(ENDP0, EP_RX_NAK);
      _SetEPTxStatus(ENDP0, EP_TX_NAK);


      /* DIR bit = origin of the interrupt */

      if ((wIstr & ISTR_DIR) == 0)
      {
        /* DIR = 0 */

        /* DIR = 0      = > IN  int */
        /* DIR = 0 implies that (EP_CTR_TX = 1) always  */


        _ClearEP_CTR_TX(ENDP0);
        In0_Process();

           /* before terminate set Tx & Rx status */
          _SetEPRxStatus(ENDP0, SaveRState);
          _SetEPTxStatus(ENDP0, SaveTState);
          return;
      }
      else
      {
        /* DIR = 1 */

        /* DIR = 1 & CTR_RX       = > SETUP or OUT int */
        /* DIR = 1 & (CTR_TX | CTR_RX) = > 2 int pending */

        wEPVal = _GetENDPOINT(ENDP0);
        if ((wEPVal & EP_CTR_TX) != 0)
        {
          _ClearEP_CTR_TX(ENDP0);
          In0_Process();
          /* before terminate set Tx & Rx status */
          _SetEPRxStatus(ENDP0, SaveRState);
          _SetEPTxStatus(ENDP0, SaveTState);
          return;
        }
        else if ((wEPVal &EP_SETUP) != 0)
        {
          _ClearEP_CTR_RX(ENDP0); /* SETUP bit kept frozen while CTR_RX = 1 */
          Setup0_Process();
          /* before terminate set Tx & Rx status */
          _SetEPRxStatus(ENDP0, SaveRState);
          _SetEPTxStatus(ENDP0, SaveTState);
          return;
        }

        else if ((wEPVal & EP_CTR_RX) != 0)
        {
          _ClearEP_CTR_RX(ENDP0);
          Out0_Process();
          /* before terminate set Tx & Rx status */
          _SetEPRxStatus(ENDP0, SaveRState);
          _SetEPTxStatus(ENDP0, SaveTState);
          return;
        }
      }
    }/* if(EPindex == 0) */
    else
    {
      /* Decode and service non control endpoints interrupt  */

      /* process related endpoint register */
      wEPVal = _GetENDPOINT(EPindex);
      if ((wEPVal & EP_CTR_RX) != 0)
      {
        /* clear int flag */
        _ClearEP_CTR_RX(EPindex);

        /* call OUT service function */
        (*pEpInt_OUT[EPindex-1])();

      } /* if((wEPVal & EP_CTR_RX) */

      if ((wEPVal & EP_CTR_TX) != 0)
      {
        /* clear int flag */
        _ClearEP_CTR_TX(EPindex);

        /* call IN service function */
        (*pEpInt_IN[EPindex-1])();
      } /* if((wEPVal & EP_CTR_TX) != 0) */

    }/* if(EPindex == 0) else */

  }/* while(...) */
}

3 CTR_HP

CTR_HP為高優先級端點傳輸正常時的中斷服務函數，代碼如下。

/*******************************************************************************
* Function Name  : CTR_HP.
* Description    : High Priority Endpoint Correct Transfer interrupt's service 
*                  routine.
* Input          : None.
* Output         : None.
* Return         : None.
*******************************************************************************/
void CTR_HP(void)
{
  uint32_t wEPVal = 0;

  while (((wIstr = _GetISTR()) & ISTR_CTR) != 0)
  {
    _SetISTR((uint16_t)CLR_CTR); /* clear CTR flag */
    /* extract highest priority endpoint number */
    EPindex = (uint8_t)(wIstr & ISTR_EP_ID);
    /* process related endpoint register */
    wEPVal = _GetENDPOINT(EPindex);
    if ((wEPVal & EP_CTR_RX) != 0)
    {
      /* clear int flag */
      _ClearEP_CTR_RX(EPindex);

      /* call OUT service function */
      (*pEpInt_OUT[EPindex-1])();

    } /* if((wEPVal & EP_CTR_RX) */
    else if ((wEPVal & EP_CTR_TX) != 0)
    {
      /* clear int flag */
      _ClearEP_CTR_TX(EPindex);

      /* call IN service function */
      (*pEpInt_IN[EPindex-1])();


    } /* if((wEPVal & EP_CTR_TX) != 0) */

  }/* while(...) */
}

4 CTR_LP和CTR_HP各自處理的事務類型

這兩個函數定義在usb_int.c中，用法如下。

CTR_LP（低優先級中斷Low-priority interrupt），用于控制傳輸、中斷傳輸、批量傳輸（ 單緩沖模式）。

CTR_HP（高優先級中斷 High-priority interrupt），用于快速大數據量傳輸處理，比如同步傳輸、批量傳輸，但是都是處理雙緩沖模式。

5 核心注意要點

如果把只初始化了USB_LP_CAN1_RX0_IRQn中斷向量，則所有的正確傳輸中斷只會進入USB_LP_CAN1_RX0_IRQHandler->CTR_LP，所以要想進入CTR_HP必須對其中斷向量進行初始化，否則會使用默認的CTR_LP路徑進行處理。