CubeMx中HAL在学习中，库函数的调用不同于库函数的调用CubeMx不懂串口通信HAL库中的回调函数是如何调用的，所以查看每个定义，参考别人写的博客，终于明白了HAL库中断调用不同于库函数。写这个博客是为了加深他们的理解，第二个是希望不理解HAL库中回调函数调用机制的朋友有帮助。
参考工程代码：【STM32】-CubeMX-HAL库-UART-串口通信-STM32F103C8T6-收发测试
在库函数中，UART串口中断时，我们直接将业务代码写在上面void USART1_IRQHandler(void)中，如下图：
void USART1_IRQHandler(void) ///串口1中断服务程序 { u8 Res; if(USART_GetITStatus(USART1, USART_IT_RXNE) != RESET) ///接收中断(接收到的数据必须是0x0d 0x0a结尾) { Res =USART_ReceiveData(USART1); ////读取收到的数据 if((USART_RX_STA&0x8000)==0)//未完成接收 { if(USART_RX_STA&0x4000)//收到0x0d { if(Res!=0x0a)USART_RX_STA=0./接收错误，重新开始 else USART_RX_STA|=0x8000; //接收完成了 } else ///还没收到0X0D { if(Res==0x0d)USART_RX_STA|=0x4000; else { USART_RX_BUF[USART_RX_STA&0X3FFF]=Res ; USART_RX_STA ; if(USART_RX_STA>(USART_REC_LEN-1))USART_RX_STA=0.//接收数据错误，重新开始接收 } } } } } 对于CubeMX生成的代码，USART1_IRQHandler(void)为了提高中断效率，函数采用了回调机制。(中断关闭后可以处理业务代码，这样中断处理就不会占用太多时间来影响程序的执行效率)
USART1_IRQHandler(void)只调用函数HAL_UART_IRQHandler(&huart1)（可以在STM32f1xx_it.c中找到），参数为uart1的句柄huart1.句柄可以理解为通过huart1访问到uart如果不了解各种寄存器和数据类型，可以去看看。UART_HandleTypeDef结构体的定义。
static HAL_StatusTypeDef UART_Receive_IT(UART_HandleTypeDef *huart) { 用这个指针指向我们接收数据的变量或数组，在收发试验例程中定义char Res uint8_t *pdata8bits; uint16_t *pdata16bits; /* Check that a Rx process is ongoing */ if (huart->RxState == HAL_UART_STATE_BUSY_RX) { if ((huart->Init.WordLength == UART_WORDLENGTH_9B) && (huart->Init.Parity == UART_PARITY_NONE)) { pdata8bits = NULL; pdata16bits = (uint16_t *) huart->pRxBuffPtr;//指向Res,相当于pdata16bits=&Res //参考具体原因HAL_UART_Receive_IT(&huart1, &Res, 1); *pdata16bits = (uint16_t)(huart->Instance->DR & (uint16_t)0x01FF); huart->pRxBuffPtr = 2U; } else { pdata8bits = (uint8_t *) huart->pRxBuffPtr;//指向Res,相当于pdata8bits=&Res pdata16bits = NULL; if ((huart->Init.WordLength == UART_WORDLENGTH_9B) || ((huart->Init.WordLength == UART_WORDLENGTH_8B) && (huart->Init.Parity == UART_PARITY_NONE))) { ////指针操作 相当于Res= (uint8_t)(huart->Instance->DR & (uint8_t)0x00FF); *pdata8bits = (uint8_t)(huart->Instance->DR & (uint8_t)0x00FF); } else { ////指针操作 相当于Res= (uint8_t)(huart->Instance->DR & (uint8_t)0x00FF); *pdata8bits = (uint8_t)(huart->Instance->DR & (uint8_t)0x007F); } huart->pRxBuffPtr = 1U; } if (--huart->RxXferCount == 0U)//关闭中断，准备回调，保存串口接收到的数据 { /* Disable the UART Data Register not empty Interrupt */ __HAL_UART_DISABLE_IT(huart, UART_IT_RXNE); /* Disable the UART Parity Error Interrupt */ __HAL_UART_DISABLE_IT(huart, UART_IT_PE); /* Disable the UART Error Interrupt: (Frame error, noise error, overrun error) */ __HAL_UART_DISABLE_IT(huart, UART_IT_ERR); /* Rx process is completed, restore huart->RxState to Ready */ huart->RxState = HAL_UART_STATE_READY; /* Check current reception Mode : If Reception till IDLE event has been selected : */ if (huart->ReceptionType == HAL_UART_RECEPTION_TOIDLE) { /* Set reception type to Standard */ huart->ReceptionType = HAL_UART_RECEPTION_STANDARD; /* Disable IDLE interrupt */ CLEAR_BIT(huart->Instance->CR1, USART_CR1_IDLEIE); /* Check if IDLE flag is set */ if (__HAL_UART_GET_FLAG(huart, UART_FLAG_IDLE)) { /* Clear IDLE flag in ISR */ __HAL_UART_CLEAR_IDLEFLAG(huart); } #if (USE_HAL_UART_REGISTER_CALLBACKS == 1) /*Call registered Rx Event callback*/ huart->RxEventCallback(huart, huart->RxXferSize); #else /*Call legacy weak Rx Event callback*/ HAL_UARTEx_RxEventCallback(huart, huart->RxXferSize); #endif } else { /* Standard reception API called */ #if (USE_HAL_UART_REGISTER_CALLBACKS == 1) /*Call registered Rx complete callback*/ huart->RxCpltCallback(huart); #ese
/*Call legacy weak Rx complete callback*/
HAL_UART_RxCpltCallback(huart);//正常情况下会执行这一条语句
//我们可以自己定义这个函数内部的具体操作
#endif /* USE_HAL_UART_REGISTER_CALLBACKS */
}
return HAL_OK;
}
return HAL_OK;
}
else
{
return HAL_BUSY;
}
}表格中左右两边的操作为什么等价呢？
| pdata8bits = (uint8_t *) huart->pRxBuffPtr; | pdata8bits=&Res |
| *pdata8bits = (uint8_t)(huart->Instance->DR & (uint8_t)0x00FF); | Res= (uint8_t)(huart->Instance->DR & (uint8_t)0x00FF); |
可以从UART_Start_Receive_IT函数中找到答案
（UART_Start_Receive_IT被main函数中的HAL_UART_Receive_IT调用）
//函数参数相当于（&huart1, &Res, 1）
HAL_StatusTypeDef UART_Start_Receive_IT(UART_HandleTypeDef *huart, uint8_t *pData, uint16_t Size)
{
//函数参数相当于（&huart1, &Res, 1）
huart->pRxBuffPtr = pData;//pData==&Res
//在UART_Receive_IT函数中 pdata8bits = (uint8_t *) huart->pRxBuffPtr;
//pdata8bits=&Res，其他都是同理，如果不理解，需要回顾一下指针操作。
huart->RxXferSize = Size;//Size==1
huart->RxXferCount = Size;
huart->ErrorCode = HAL_UART_ERROR_NONE;
huart->RxState = HAL_UART_STATE_BUSY_RX;
/* Process Unlocked */
__HAL_UNLOCK(huart);
/* Enable the UART Parity Error Interrupt */
__HAL_UART_ENABLE_IT(huart, UART_IT_PE);
/* Enable the UART Error Interrupt: (Frame error, noise error, overrun error) */
__HAL_UART_ENABLE_IT(huart, UART_IT_ERR);
/* Enable the UART Data Register not empty Interrupt */
__HAL_UART_ENABLE_IT(huart, UART_IT_RXNE);
return HAL_OK;
}
void HAL_UART_RxCpltCallback(UART_HandleTypeDef *huart)//自定义回调函数 在UART_Receive_IT()中调用 { //判断是哪个串口触发的中断 huart1.Instance = USART1;定义在MX_USART1_UART_Init中 if(huart==&huart1)//huart ->Instance == USART1两种判断条件等价 { if((UART1_RX_STA & 0x8000)==0)//接收未完成&位运算符 &&短路与判断 { if(UART1_RX_STA & 0x4000)//接收到 \r { if(Res==0x0a)//下一个必须是接收 \n UART1_RX_STA|=0x8000; else UART1_RX_STA=0; } else //未接收到\r { if(Res==0x0d)//Receive \r { UART1_RX_STA|=0x4000; } else { UART1_RX_Buffer[UART1_RX_STA&0X3FFF]=Res; UART1_RX_STA++; if(UART1_RX_STA>UART1_REC_LEN-1) UART1_RX_STA=0;//如果接收数据大于200Byte 重新开始接收 } } } HAL_UART_Receive_IT(&huart1, &Res, 1);//完成一次接受，再此开启中断 } }
如果我们自己没有定义回调函数的话，系统会调用自带的回调函数，函数类型为__weak，表示弱定义
如果用户自己定义了函数就优先调用用户定义的回调函数
__weak void HAL_UART_RxCpltCallback(UART_HandleTypeDef *huart)
{
/* Prevent unused argument(s) compilation warning */
UNUSED(huart);
/* NOTE: This function should not be modified, when the callback is needed,
the HAL_UART_RxCpltCallback could be implemented in the user file
*/
}