stm32串口定長DMA接收 + 數據錯位糾正

串口dma接收配置

• 使用的芯片為stm32F407
• 接收串口為串口六

__IO uint8_t Rx_data[12]={0};   //dma數據存放數組

void Initial_UART6(unsigned long baudrate)
{
 	GPIO_InitTypeDef GPIO_InitStructure;
        DMA_InitTypeDef DMA_InitStructure;
	USART_InitTypeDef USART_InitStructure;
	NVIC_InitTypeDef NVIC_InitStructure;
	
	
        //時鍾使能
	RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOG,ENABLE);
	RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART6,ENABLE);
        RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_DMA2,ENABLE);//DMA2時鍾使能 

        /********GPIO 配置**********/
	GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9 | GPIO_Pin_14;
	GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
	GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
	GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
	GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP;
	GPIO_Init(GPIOG, &GPIO_InitStructure);
	GPIO_PinAFConfig(GPIOG,GPIO_PinSource9,GPIO_AF_USART6); //GPIOG9復用為USART6
	GPIO_PinAFConfig(GPIOG,GPIO_PinSource14,GPIO_AF_USART6); //GPIOG14復用為USART6
	
	/**********DMA配置*************/
	DMA_DeInit(DMA2_Stream2);
	while (DMA_GetCmdStatus(DMA2_Stream2) != DISABLE){}//等待DMA可配置 
	DMA_InitStructure.DMA_Channel=DMA_Channel_5;
	DMA_InitStructure.DMA_PeripheralBaseAddr=(u32)&USART6->DR;
	DMA_InitStructure.DMA_Memory0BaseAddr = (uint32_t)&Rx_data[0];
	DMA_InitStructure.DMA_BufferSize = 12;//數據傳輸量 
	DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;//外設非增量模式
	DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable;//存儲器增量模式
	DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_Byte;//外設數據長度:8位
	DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_Byte;//存儲器數據長度:8位
	DMA_InitStructure.DMA_Mode = DMA_Mode_Circular; //循環接收模式
	DMA_InitStructure.DMA_Priority = DMA_Priority_High;//高優先級
	DMA_Init(DMA2_Stream2, &DMA_InitStructure);//初始化DMA Stream
    

        /**********串口配置*************/
	USART_InitStructure.USART_BaudRate = baudrate;
	USART_InitStructure.USART_WordLength = USART_WordLength_8b;
	USART_InitStructure.USART_StopBits = USART_StopBits_1;
	USART_InitStructure.USART_Parity = USART_Parity_No ;
	USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;
	USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;
	USART_Init(USART6, &USART_InitStructure); 
	USART_DMACmd(USART6,USART_DMAReq_Rx,ENABLE);  //使能串口6的DMA接收


	/********dma傳輸完成中斷配置***************/
        NVIC_InitStructure.NVIC_IRQChannel = DMA2_Stream2_IRQn;//串口1中斷通道
	NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority=1;//搶占優先級1
	NVIC_InitStructure.NVIC_IRQChannelSubPriority =3;		//子優先級3
	NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;			//IRQ通道使能
	NVIC_Init(&NVIC_InitStructure);	//根據指定的參數初始化VIC寄存器、

	USART_Cmd(USART6, ENABLE);      //使能串口
	DMA_ITConfig(DMA2_Stream2,DMA_IT_TC,ENABLE); //開啟dma接收完成中斷
        DMA_Cmd(DMA2_Stream2, ENABLE);   //開啟dma傳輸
}

數據錯位糾正

這里我們主要使用校驗的方式判斷數據是否錯位，可選的方法有CRC校驗以及幀頭幀尾校驗。
為了方便起見並且減少計算量，我選擇了幀頭幀尾校驗。

DMA傳輸完成中斷函數
void DMA2_Stream2_IRQHandler(void)
{
	if(DMA_GetFlagStatus(DMA2_Stream2,DMA_IT_TCIF2) == SET)
	{
                //校驗不通過重啟dma接收
		if(Rx_data[0]!=0XAA || Rx_data[11]!=0xA0)  //這里我選擇了0xaa作為幀頭，0xa0作為幀尾。此處校驗不通過
		{
			//printf("RX ERROR!!!\r\n");     
			DMA_Cmd(DMA2_Stream2,DISABLE);    
			DMA_SetCurrDataCounter(DMA2_Stream2,12); //重設傳輸量
			delay_us(500);                  //此處延時根據實際情況修改
			DMA_Cmd(DMA2_Stream2,ENABLE);
		}
		else
		{
			printf("RX SUCCESSFUL!!!\r\n");
		}
	}
	DMA_ClearFlag(DMA2_Stream2, DMA_FLAG_TCIF2);  //清楚標志位
}