stm32兩種常見的串口接收方式

最近遇到一直增加功能和調試中不知不覺把帶串口接收DMA的串口資源給用完了，換成不帶DMA的串口接收數據有點不一樣的地方，記錄一下，還有以後的開發中不能老是買通信都是串口的模塊，模塊多的時候，不利於擴展
串口1+DMA接收數據的基本配置
下面的這段代碼是串口+DMA接收數據的配置，配置完後在中斷裏的**receive_process（）**函數添加數據處理即可,這種方式不需要CPU參與，可以節省CPU資源

static uint8_t recv_buf[100];  //放置接收數據

static void set_gpio_config(void);
static void usart_gpio_config(void);
static void nvic_config(void);
static void usart_config(uint32_t baud_rate);
static void dma_config(void);
static void start_wireless_module(void);
/***********************************************************************************************
*
* @brief
* @param    none
* @return   none
*
************************************************************************************************/
void wireless_module_config(void)
{
	usart_gpio_config();
	
	wireless_module_param_config();

	usart_config(BAUD_RATE);  //BAUD_RATE 這裏需自定義波特率

	nvic_config();	

	dma_config();

	start_wireless_module();
}

/***********************************************************************************************
*
* @brief
* @param    none
* @return   none
*
************************************************************************************************/
static void usart_gpio_config(void)
{
	GPIO_InitTypeDef GPIO_InitStructure;

	RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE);

	GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9;   
	GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;  
	GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;  
	GPIO_Init(GPIOA, &GPIO_InitStructure); 

	GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10;   
	GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;  
	GPIO_Init(GPIOA, &GPIO_InitStructure);
}
/***********************************************************************************************
*
* @brief
* @param    none
* @return   none
*
************************************************************************************************/
static void nvic_config(void)
{
	NVIC_InitTypeDef NVIC_InitStructure;

	NVIC_InitStructure.NVIC_IRQChannel = USART1_IRQn;
	NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 1;
	NVIC_InitStructure.NVIC_IRQChannelSubPriority = 2;
	NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
	NVIC_Init(&NVIC_InitStructure);
}
/***********************************************************************************************
*
* @brief
* @param    none
* @return   none
*
************************************************************************************************/
static void usart_config(uint32_t baud_rate)
{
	USART_InitTypeDef USART_InitStruct;	

	RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1, ENABLE);

	USART_InitStruct.USART_BaudRate = baud_rate;
	USART_InitStruct.USART_WordLength = USART_WordLength_8b;
	USART_InitStruct.USART_StopBits = USART_StopBits_1;
	USART_InitStruct.USART_Parity = USART_Parity_No;
	USART_InitStruct.USART_HardwareFlowControl = USART_HardwareFlowControl_None;
	USART_InitStruct.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;
	
	USART_Init(USART1, &USART_InitStruct);
    USART_Cmd(USART1, ENABLE);
	USART_DMACmd(USART1, USART_DMAReq_Rx, ENABLE);
	USART_ITConfig(USART1, USART_IT_IDLE, ENABLE);
}
/***********************************************************************************************
*
* @brief
* @param    none
* @return   none
*
************************************************************************************************/
static void dma_config(void)
{
	DMA_InitTypeDef DMA_InitStructure;

	RCC_AHBPeriphClockCmd(RCC_AHBPeriph_DMA1, ENABLE);
	DMA_DeInit(DMA1_Channel5);

	DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t)(&USART1->DR);
	DMA_InitStructure.DMA_MemoryBaseAddr = (uint32_t)recv_buf;
	DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralSRC;
	DMA_InitStructure.DMA_BufferSize = 100;
	DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;
	DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable;
	DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_Byte;
	DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_Byte;
	DMA_InitStructure.DMA_Mode = DMA_Mode_Normal;
	DMA_InitStructure.DMA_Priority = DMA_Priority_VeryHigh;
	DMA_InitStructure.DMA_M2M = DMA_M2M_Disable;
	DMA_Init(DMA1_Channel5, &DMA_InitStructure);	
	DMA_Cmd(DMA1_Channel5, ENABLE);
}
/***********************************************************************************************
*
* @brief
* @param    none
* @return   none
*
************************************************************************************************/
void start_wireless_module(void)
{
	USART_DMACmd(USART1, USART_DMAReq_Rx, ENABLE);
	USART_ClearITPendingBit(USART1, USART_IT_IDLE);	
	USART_ITConfig(USART1, USART_IT_IDLE, ENABLE);	
}

/***********************************************************************************************
*
* @brief
* @param    none
* @return   none
*
************************************************************************************************/
void USART1_IRQHandler(void)
{
	uint8_t len;
	
	if(USART_GetITStatus(USART1, USART_IT_IDLE) != RESET)
	{
		len = 100 - DMA1_Channel5->CNDTR;		
		receive_process(recv_buf, len);
		DMA_Cmd(DMA1_Channel5, DISABLE);
		DMA1_Channel5->CNDTR = 100;
		DMA_Cmd(DMA1_Channel5, ENABLE);
		
		USART_ClearITPendingBit(USART1, USART_IT_IDLE);
		USART_ReceiveData(USART1);
	}
  if(USART_GetFlagStatus(USART1,USART_FLAG_ORE) == SET) //check ORE mark 
  {
    USART_ClearFlag(USART1,USART_FLAG_ORE);
    USART_ReceiveData(USART1);
  }
}

還有一種就是普通的串口中斷接收處理函數，引腳和中斷配置和上面相同，串口和中斷處理函數如下

/***********************************************************************************************
*
* @brief
* @param    none
* @return   none
*
************************************************************************************************/
static void usart4_config(uint32_t baud_rate)
{
	USART_InitTypeDef USART_InitStruct;	

	RCC_APB1PeriphClockCmd(RCC_APB1Periph_UART4, ENABLE);

	USART_InitStruct.USART_BaudRate = baud_rate;
	USART_InitStruct.USART_WordLength = USART_WordLength_8b;
	USART_InitStruct.USART_StopBits = USART_StopBits_1;
	USART_InitStruct.USART_Parity = USART_Parity_No;
	USART_InitStruct.USART_HardwareFlowControl = USART_HardwareFlowControl_None;
	USART_InitStruct.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;
	
	USART_Init(UART4, &USART_InitStruct);
  USART_ITConfig(UART4, USART_IT_RXNE, ENABLE);
  USART_Cmd(UART4, ENABLE);
}
/***********************************************************************************************
*
* @brief
* @param    none
* @return   none
*
************************************************************************************************/
void UART4_IRQHandler() 
{ 
     if(USART_GetITStatus(UART4,USART_IT_RXNE) != RESET) //中斷產生 
     { 
        USART_ClearITPendingBit(UART4,USART_IT_RXNE); //清除中斷標誌
        ultra_recv_buf[ultra_data_len] = USART_ReceiveData(UART4); 
        ultra_data_len++; 
   //此處可以寫爲一個處理函數封裝起來比較好    
      if((ultra_data_len >= 6)&&(ultra_data_len <= 99))    //此處爲一個七個字節的一幀的處理函數
      {
        if((ultra_recv_buf[ultra_data_len - 6] == 0xCB)&&(ultra_recv_buf[ultra_data_len - 5] == 0x55))  //判斷兩個字節幀頭是否正確
        { //正確的話就接收數據
           ultra_distance_buf[0]  = ultra_recv_buf[ultra_data_len - 4];	
           ultra_distance_buf[1]  = ultra_recv_buf[ultra_data_len - 3];
           ultra_distance_buf[2]  = ultra_recv_buf[ultra_data_len - 2];
           ultra_distance_buf[3]  = ultra_recv_buf[ultra_data_len - 1];
           ultra_distance_buf[4]  = ultra_recv_buf[ultra_data_len];
        }
      }
      else if(ultra_data_len > 99)
      {
        ultra_data_len = 0;
      }
     } 
     if(USART_GetFlagStatus(UART4,USART_FLAG_ORE) == SET) 
     { 
            USART_ClearFlag(UART4,USART_FLAG_ORE);  
            USART_ReceiveData(UART4); 
     } 
}