STM32+串口空闲中断实现不定长数据接收

常见的数据帧断帧方式有两种，一种是通过固定的协议格式断帧，另外一个是通过两帧数据的时间断帧，下面介绍最后一种，利用STM32F1的串口空闲中断实现不定长的数据断帧。笔者使用的标准官方库。

空闲中断是接受数据后出现一个字节的空闲状态，就会触发空闲中断。利用该特性区分两个不同数据帧。

1.初始化USART

​ 按照官方的初始化流程配置，需要注意一点就是需要开启接收中断和空闲中断。

/**
  * @brief  USART初始化.
  * @param
	* @arg BaudRate 波特率
  * @retval None
  */
void Usart_Init(uint32_t baudrate)
{
	USART_DeInit(USART1);
<span class="token function">RCC_APB2PeriphClockCmd</span><span class="token punctuation">(</span>RCC_APB2Periph_USART1<span class="token punctuation">,</span> ENABLE<span class="token punctuation">)</span><span class="token punctuation">;</span>
USART_InitStructure<span class="token punctuation">.</span>USART_BaudRate <span class="token operator">=</span> baudrate<span class="token punctuation">;</span>
USART_InitStructure<span class="token punctuation">.</span>USART_WordLength <span class="token operator">=</span> USART_WordLength_8b<span class="token punctuation">;</span>
USART_InitStructure<span class="token punctuation">.</span>USART_StopBits <span class="token operator">=</span> USART_StopBits_2<span class="token punctuation">;</span>
USART_InitStructure<span class="token punctuation">.</span>USART_Parity <span class="token operator">=</span> USART_Parity_No<span class="token punctuation">;</span>
USART_InitStructure<span class="token punctuation">.</span>USART_HardwareFlowControl <span class="token operator">=</span> USART_HardwareFlowControl_None<span class="token punctuation">;</span>
USART_InitStructure<span class="token punctuation">.</span>USART_Mode <span class="token operator">=</span> USART_Mode_Rx <span class="token operator">|</span> USART_Mode_Tx<span class="token punctuation">;</span>
<span class="token function">USART_Init</span><span class="token punctuation">(</span>USART1<span class="token punctuation">,</span> <span class="token operator">&amp;</span>USART_InitStructure<span class="token punctuation">)</span><span class="token punctuation">;</span>

<span class="token function">USART_ITConfig</span><span class="token punctuation">(</span>USART1<span class="token punctuation">,</span> USART_IT_RXNE<span class="token punctuation">,</span> ENABLE<span class="token punctuation">)</span><span class="token punctuation">;</span>		<span class="token comment">//开启接收中断</span>
<span class="token function">USART_ITConfig</span><span class="token punctuation">(</span>USART1<span class="token punctuation">,</span> USART_IT_IDLE<span class="token punctuation">,</span> ENABLE<span class="token punctuation">)</span><span class="token punctuation">;</span>		<span class="token comment">//开启空闲中断</span>

NVIC_InitStructure<span class="token punctuation">.</span>NVIC_IRQChannel <span class="token operator">=</span> USART1_IRQn<span class="token punctuation">;</span>
NVIC_InitStructure<span class="token punctuation">.</span>NVIC_IRQChannelPreemptionPriority <span class="token operator">=</span> <span class="token number">1</span><span class="token punctuation">;</span>
NVIC_InitStructure<span class="token punctuation">.</span>NVIC_IRQChannelSubPriority <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span>
NVIC_InitStructure<span class="token punctuation">.</span>NVIC_IRQChannelCmd <span class="token operator">=</span> ENABLE<span class="token punctuation">;</span>
<span class="token function">NVIC_Init</span><span class="token punctuation">(</span><span class="token operator">&amp;</span>NVIC_InitStructure<span class="token punctuation">)</span><span class="token punctuation">;</span>

<span class="token function">USART_Cmd</span><span class="token punctuation">(</span>USART1<span class="token punctuation">,</span> ENABLE<span class="token punctuation">)</span><span class="token punctuation">;</span>

}

2.实现中断接收

​ 代码如下：

#define RXBUFF_SIZE	100
uint8_t rxbuff[RXBUFF_SIZE];
uint8_t rx_index;
uint8_t rec_over;
/**
  * @brief  USART接收中断.
  * @param  None
  * @retval None
  */
void RxIrqDeal()
{
	uint8_t temp;
	if(USART_GetFlagStatus(USART1, USART_FLAG_ORE) != RESET){	   //防止溢出中断
		USART_ReceiveData(USART1); 
	}   
	if(USART_GetITStatus(USART1, USART_IT_RXNE) != RESET){		//USART接收中断
        temp = USART_ReceiveData(USART1);
		if(rx_index > RXBUFF_SIZE){		   //溢出不再接收数据
			return;
		}
		rxbuff[rx_index++] = temp;
	}
	else if(USART_GetFlagStatus(USART1, USART_FLAG_IDLE) != RESET){		//USART空闲中断
		USART_ReceiveData(USART1);
		rec_over = 1;		//接收完成
	}
}void USART1_IRQHandler(void)
{
	RxIrqDeal();
}

​ 这里有几个需要注意的地方，

​ 1.开启接收中断的同时会开启ORE中断

​ 2.IDLE中断和ORE中断需要USART_GetFlagStatus获取中断标识后通过读取USART_SR寄存器消除。这里可以从标准的函数说明可以看出，图下红框部分。

3.提取缓存数据

​ 在应用层中判断接收完成标志位，按照用户定义的通讯格式解析数据。

/**
  * @brief  解析缓存数据.
  * @param  None
  * @retval None
  */
void  app_task()
{
	if(rec_over){
		rec_over = 0;
		//TODO
	}
}