1 STM32F1两个USB中断入口
STM32中断入口有两个，分别是USB_HP_CAN1_TX_IRQHandler和USB_LP_CAN1_RX0_IRQHandler。
其中USB_Istr函数调用了CTR_LP函数，代码如下。
/*******************************************************************************
* 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为低优先级端点传输正常时的中断服务函数，控制传输只能在CTR_LP里面处理，代码如下。
/*******************************************************************************
* 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为高优先级端点传输正常时的中断服务函数，代码如下。
/*******************************************************************************
* 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各自处理的事务类型
这两个函数定义在usb_int.c中，用法如下。
CTR_LP（低优先级中断Low-priority interrupt），用于控制传输、中断传输、批量传输（ 单缓冲模式）。
CTR_HP（高优先级中断 High-priority interrupt），用于快速大数据量传输处理，比如同步传输、批量传输，但是都是处理双缓冲模式。
5 核心注意要点
如果把只初始化了USB_LP_CAN1_RX0_IRQn中断向量，则所有的正确传输中断只会进入USB_LP_CAN1_RX0_IRQHandler->CTR_LP，所以要想进入CTR_HP必须对其中断向量进行初始化，否则会使用默认的CTR_LP路径进行处理。