HAL库USART中断接收的相关问题

一、使用中断的步骤

1、配置GPIO
2、配置USART1
3、设置UART1中断优先级（不开启手动中断，中断由HAL库给好的函数开启）
4、设置USART1中断服务函数（调用HAL给好的中断服务函数）
5、设置回调函数（HAL定义了一个弱函数，需要用户自己重定义）
6、开启USART1接收中断

二、相关函数分析

1、HAL_UART_IRQHandler

在中断服务函数USART1_IRQHandler中调用，进行USART中断的处理。

void USART1_IRQHandler(void)
{HAL_UART_IRQHandler(&huart1);
}

查看函数源码

void HAL_UART_IRQHandler(UART_HandleTypeDef *huart)
{uint32_t isrflags   = READ_REG(huart->Instance->SR); //#define READ_REG(REG)         ((REG))uint32_t cr1its     = READ_REG(huart->Instance->CR1);uint32_t cr3its     = READ_REG(huart->Instance->CR3);uint32_t errorflags = 0x00U;uint32_t dmarequest = 0x00U;/* If no error occurs */errorflags = (isrflags & (uint32_t)(USART_SR_PE | USART_SR_FE | USART_SR_ORE | USART_SR_NE));//USART_SR_PE 32位，PE位为1，其余为0，是一个掩码  #define USART_SR_PE   USART_SR_PE_Msk  //  isrflags 时SR的值，与这几位的掩码与，若这些位无置位则结果位0.表示错误位都没有置为，无错误发生if (errorflags == RESET)// == 0 无错误{/* UART in mode Receiver -------------------------------------------------*/if (((isrflags & USART_SR_RXNE) != RESET) && ((cr1its & USART_CR1_RXNEIE) != RESET)){//接收数据寄存器非空 且 接收中断使能UART_Receive_IT(huart);//中断接收函数return;}}
//错误发生时/* If some errors occur */if ((errorflags != RESET) && (((cr3its & USART_CR3_EIE) != RESET)|| ((cr1its & (USART_CR1_RXNEIE | USART_CR1_PEIE)) != RESET))){/* UART parity error interrupt occurred ----------------------------------*/if (((isrflags & USART_SR_PE) != RESET) && ((cr1its & USART_CR1_PEIE) != RESET)){huart->ErrorCode |= HAL_UART_ERROR_PE;}/* UART noise error interrupt occurred -----------------------------------*/if (((isrflags & USART_SR_NE) != RESET) && ((cr3its & USART_CR3_EIE) != RESET)){huart->ErrorCode |= HAL_UART_ERROR_NE;}/* UART frame error interrupt occurred -----------------------------------*/if (((isrflags & USART_SR_FE) != RESET) && ((cr3its & USART_CR3_EIE) != RESET)){huart->ErrorCode |= HAL_UART_ERROR_FE;}/* UART Over-Run interrupt occurred --------------------------------------*/if (((isrflags & USART_SR_ORE) != RESET) && (((cr1its & USART_CR1_RXNEIE) != RESET)|| ((cr3its & USART_CR3_EIE) != RESET))){huart->ErrorCode |= HAL_UART_ERROR_ORE;}/* Call UART Error Call back function if need be --------------------------*/if (huart->ErrorCode != HAL_UART_ERROR_NONE){/* UART in mode Receiver -----------------------------------------------*/if (((isrflags & USART_SR_RXNE) != RESET) && ((cr1its & USART_CR1_RXNEIE) != RESET)){UART_Receive_IT(huart);}/* If Overrun error occurs, or if any error occurs in DMA mode reception,consider error as blocking */dmarequest = HAL_IS_BIT_SET(huart->Instance->CR3, USART_CR3_DMAR);if (((huart->ErrorCode & HAL_UART_ERROR_ORE) != RESET) || dmarequest){/* Blocking error : transfer is abortedSet the UART state ready to be able to start again the process,Disable Rx Interrupts, and disable Rx DMA request, if ongoing */UART_EndRxTransfer(huart);/* Disable the UART DMA Rx request if enabled */if (HAL_IS_BIT_SET(huart->Instance->CR3, USART_CR3_DMAR)){ATOMIC_CLEAR_BIT(huart->Instance->CR3, USART_CR3_DMAR);/* Abort the UART DMA Rx channel */if (huart->hdmarx != NULL){/* Set the UART DMA Abort callback :will lead to call HAL_UART_ErrorCallback() at end of DMA abort procedure */huart->hdmarx->XferAbortCallback = UART_DMAAbortOnError;if (HAL_DMA_Abort_IT(huart->hdmarx) != HAL_OK){/* Call Directly XferAbortCallback function in case of error */huart->hdmarx->XferAbortCallback(huart->hdmarx);}}else{/* Call user error callback */
#if (USE_HAL_UART_REGISTER_CALLBACKS == 1)/*Call registered error callback*/huart->ErrorCallback(huart);
#else/*Call legacy weak error callback*/HAL_UART_ErrorCallback(huart);
#endif /* USE_HAL_UART_REGISTER_CALLBACKS */}}else{/* Call user error callback */
#if (USE_HAL_UART_REGISTER_CALLBACKS == 1)/*Call registered error callback*/huart->ErrorCallback(huart);
#else/*Call legacy weak error callback*/HAL_UART_ErrorCallback(huart);
#endif /* USE_HAL_UART_REGISTER_CALLBACKS */}}else{/* Non Blocking error : transfer could go on.Error is notified to user through user error callback */
#if (USE_HAL_UART_REGISTER_CALLBACKS == 1)/*Call registered error callback*/huart->ErrorCallback(huart);
#else/*Call legacy weak error callback*/HAL_UART_ErrorCallback(huart);
#endif /* USE_HAL_UART_REGISTER_CALLBACKS */huart->ErrorCode = HAL_UART_ERROR_NONE;}}return;} /* End if some error occurs *//* Check current reception Mode :If Reception till IDLE event has been selected : */if ((huart->ReceptionType == HAL_UART_RECEPTION_TOIDLE)&& ((isrflags & USART_SR_IDLE) != 0U)&& ((cr1its & USART_SR_IDLE) != 0U)){__HAL_UART_CLEAR_IDLEFLAG(huart);/* Check if DMA mode is enabled in UART */if (HAL_IS_BIT_SET(huart->Instance->CR3, USART_CR3_DMAR)){/* DMA mode enabled *//* Check received length : If all expected data are received, do nothing,(DMA cplt callback will be called).Otherwise, if at least one data has already been received, IDLE event is to be notified to user */uint16_t nb_remaining_rx_data = (uint16_t) __HAL_DMA_GET_COUNTER(huart->hdmarx);if ((nb_remaining_rx_data > 0U)&& (nb_remaining_rx_data < huart->RxXferSize)){/* Reception is not complete */huart->RxXferCount = nb_remaining_rx_data;/* In Normal mode, end DMA xfer and HAL UART Rx process*/if (huart->hdmarx->Init.Mode != DMA_CIRCULAR){/* Disable PE and ERR (Frame error, noise error, overrun error) interrupts */ATOMIC_CLEAR_BIT(huart->Instance->CR1, USART_CR1_PEIE);ATOMIC_CLEAR_BIT(huart->Instance->CR3, USART_CR3_EIE);/* Disable the DMA transfer for the receiver request by resetting the DMAR bitin the UART CR3 register */ATOMIC_CLEAR_BIT(huart->Instance->CR3, USART_CR3_DMAR);/* At end of Rx process, restore huart->RxState to Ready */huart->RxState = HAL_UART_STATE_READY;huart->ReceptionType = HAL_UART_RECEPTION_STANDARD;ATOMIC_CLEAR_BIT(huart->Instance->CR1, USART_CR1_IDLEIE);/* Last bytes received, so no need as the abort is immediate */(void)HAL_DMA_Abort(huart->hdmarx);}/* Initialize type of RxEvent that correspond to RxEvent callback execution;In this case, Rx Event type is Idle Event */huart->RxEventType = HAL_UART_RXEVENT_IDLE;#if (USE_HAL_UART_REGISTER_CALLBACKS == 1)/*Call registered Rx Event callback*/huart->RxEventCallback(huart, (huart->RxXferSize - huart->RxXferCount));
#else/*Call legacy weak Rx Event callback*/HAL_UARTEx_RxEventCallback(huart, (huart->RxXferSize - huart->RxXferCount));
#endif /* USE_HAL_UART_REGISTER_CALLBACKS */}return;}else{/* DMA mode not enabled *//* Check received length : If all expected data are received, do nothing.Otherwise, if at least one data has already been received, IDLE event is to be notified to user */uint16_t nb_rx_data = huart->RxXferSize - huart->RxXferCount;if ((huart->RxXferCount > 0U)&& (nb_rx_data > 0U)){/* Disable the UART Parity Error Interrupt and RXNE interrupts */ATOMIC_CLEAR_BIT(huart->Instance->CR1, (USART_CR1_RXNEIE | USART_CR1_PEIE));/* Disable the UART Error Interrupt: (Frame error, noise error, overrun error) */ATOMIC_CLEAR_BIT(huart->Instance->CR3, USART_CR3_EIE);/* Rx process is completed, restore huart->RxState to Ready */huart->RxState = HAL_UART_STATE_READY;huart->ReceptionType = HAL_UART_RECEPTION_STANDARD;ATOMIC_CLEAR_BIT(huart->Instance->CR1, USART_CR1_IDLEIE);/* Initialize type of RxEvent that correspond to RxEvent callback execution;In this case, Rx Event type is Idle Event */huart->RxEventType = HAL_UART_RXEVENT_IDLE;#if (USE_HAL_UART_REGISTER_CALLBACKS == 1)/*Call registered Rx complete callback*/huart->RxEventCallback(huart, nb_rx_data);
#else/*Call legacy weak Rx Event callback*/HAL_UARTEx_RxEventCallback(huart, nb_rx_data);
#endif /* USE_HAL_UART_REGISTER_CALLBACKS */}return;}}/* UART in mode Transmitter ------------------------------------------------*/if (((isrflags & USART_SR_TXE) != RESET) && ((cr1its & USART_CR1_TXEIE) != RESET)){UART_Transmit_IT(huart);return;}/* UART in mode Transmitter end --------------------------------------------*/if (((isrflags & USART_SR_TC) != RESET) && ((cr1its & USART_CR1_TCIE) != RESET)){UART_EndTransmit_IT(huart);return;}
}

2、UART_Receive_IT

中断接收函数，被HAL_UART_IRQHandler 调用

static HAL_StatusTypeDef UART_Receive_IT(UART_HandleTypeDef *huart)
{uint8_t  *pdata8bits;uint16_t *pdata16bits;/* Check that a Rx process is ongoing */if (huart->RxState == HAL_UART_STATE_BUSY_RX)//判断接收过程是否任然在进行{if ((huart->Init.WordLength == UART_WORDLENGTH_9B) && (huart->Init.Parity == UART_PARITY_NONE)){//设置为9位数据而且无校验时的处理pdata8bits  = NULL;pdata16bits = (uint16_t *) huart->pRxBuffPtr;*pdata16bits = (uint16_t)(huart->Instance->DR & (uint16_t)0x01FF);huart->pRxBuffPtr += 2U;}else{pdata8bits = (uint8_t *) huart->pRxBuffPtr;//pdata16bits  = NULL;if ((huart->Init.WordLength == UART_WORDLENGTH_9B) || ((huart->Init.WordLength == UART_WORDLENGTH_8B) && (huart->Init.Parity == UART_PARITY_NONE))){//设置为8位数据时无校验或9位数据位时的处理*pdata8bits = (uint8_t)(huart->Instance->DR & (uint8_t)0x00FF);//从数据寄存器接收8位数据}else{*pdata8bits = (uint8_t)(huart->Instance->DR & (uint8_t)0x007F);//从数据寄存器接收7位数据}huart->pRxBuffPtr += 1U;//buff指针加一}if (--huart->RxXferCount == 0U)//此时已经接收了最后一位数据 huart->RxXferCount = 1;{//关闭所有中断，设置usart1 的句柄的各个标志位/* 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;/* Initialize type of RxEvent to Transfer Complete */huart->RxEventType = HAL_UART_RXEVENT_TC;/* Check current reception Mode :If Reception till IDLE event has been selected : */if (huart->ReceptionType == HAL_UART_RECEPTION_TOIDLE){//开启了空闲中断，关闭空闲中断/* Set reception type to Standard */huart->ReceptionType = HAL_UART_RECEPTION_STANDARD;/* Disable IDLE interrupt */ATOMIC_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);}
//接收完成，且开启了空闲中断时调用此函数
#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 /* USE_HAL_UART_REGISTER_CALLBACKS */}else{/* Standard reception API called *///接收完成，没有开启空闲中断时选择处理的回调函数
#if (USE_HAL_UART_REGISTER_CALLBACKS == 1)/*Call registered Rx complete callback*/huart->RxCpltCallback(huart);
#else/*Call legacy weak Rx complete callback*/HAL_UART_RxCpltCallback(huart);
#endif /* USE_HAL_UART_REGISTER_CALLBACKS */}return HAL_OK;}return HAL_OK;}else{return HAL_BUSY;}
}

3、HAL_UART_Receive_IT

判断USART句柄的接收状态，调用UART_Start_Receive_IT 开启中断。

HAL_StatusTypeDef HAL_UART_Receive_IT(UART_HandleTypeDef *huart, uint8_t *pData, uint16_t Size)
{/* Check that a Rx process is not already ongoing */if (huart->RxState == HAL_UART_STATE_READY)//判断usart状态{if ((pData == NULL) || (Size == 0U))//判断参数是否有效{return HAL_ERROR;}/* Set Reception type to Standard reception */huart->ReceptionType = HAL_UART_RECEPTION_STANDARD;//设置接收状态return (UART_Start_Receive_IT(huart, pData, Size));//调用接收中断开启函数}else{return HAL_BUSY;}
}

4、UART_Start_Receive_IT

HAL_StatusTypeDef UART_Start_Receive_IT(UART_HandleTypeDef *huart, uint8_t *pData, uint16_t Size)
{huart->pRxBuffPtr = pData;//缓冲区指针初始化huart->RxXferSize = Size;//缓冲区大小初始化huart->RxXferCount = Size;//接收数据总大小初始化  会在接收时减小huart->ErrorCode = HAL_UART_ERROR_NONE;//错误码设置huart->RxState = HAL_UART_STATE_BUSY_RX;//接收状态设置if (huart->Init.Parity != UART_PARITY_NONE){/* Enable the UART Parity Error Interrupt */__HAL_UART_ENABLE_IT(huart, UART_IT_PE);}//开启错误中断和接收中断/* 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;
}

5、总结

在使用标准库时需要我们先初始化GPIO再初始化USART，然后设置中断优先级并开启中断。在HAL库中，只需要我们初始化GPIO和USART并设置中断优先级，中断的开启和数据的接收都在HAL中封装好了函数，并使用回调函数的方式在接收完成后对数据进行处理。需要注意的是，USART的中断在HAL_UART_Receive_IT中调用UART_Start_Receive_IT开启相关中断，在ISR函数中只需调用HAL_UART_IRQHander函数。每次接收完成后相关的中断都会关闭，需要再次调用HAL_UART_Receive_IT函数开启中断，这也是刚开始用HAL库时常常疑惑的地方，为什么要在初始化时调用一次HAL_UART_Receive_IT函数，在接收完成后的处理函数中要调用HAL_UART_Receive_IT？
当然我们也可以自己调用相关的宏开启中断在ISR中写自己的处理函数，但是这样就不能够调用HAL库提供的函数接收数据了，因为在HAL库中，将外设抽象为句柄，在其中有许多的标志位，我们一旦自己自己调用中断操作后面又使用HAL库的API就会因为外设句柄中的标志位与实际不符而返回错误状态，导致程序卡死。

三、HAL库使用心得