STM32F407 标准库 串口usart2 dma 乒乓缓冲接收到的数据实例

以下是一个基于STM32F407标准库的串口USART2 DMA乒乓缓冲接收数据的示例代码：

#include "stm32f4xx.h"
#include <stdio.h>
#include <string.h>

#define RX_BUFFER_SIZE 128

uint8_t rx_buffer[RX_BUFFER_SIZE][2];  // 乒乓缓冲区
volatile uint8_t rx_index = 0;  // 当前使用的缓冲区下标
volatile uint8_t rx_length[2] = {0, 0};  // 缓冲区数据长度

void USART2_Config(void)
{
    GPIO_InitTypeDef GPIO_InitStructure;
    USART_InitTypeDef USART_InitStructure;
    DMA_InitTypeDef DMA_InitStructure;
    
    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE);
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_USART2, ENABLE);
    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_DMA1, ENABLE);
    
    // USART2 Tx PA.2 and Rx PA.3 pins configuration
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_2 | GPIO_Pin_3;
    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(GPIOA, &GPIO_InitStructure);
    
    // Connect USART2 pins to AF
    GPIO_PinAFConfig(GPIOA, GPIO_PinSource2, GPIO_AF_USART2);
    GPIO_PinAFConfig(GPIOA, GPIO_PinSource3, GPIO_AF_USART2);
    
    // USART2 configuration
    USART_InitStructure.USART_BaudRate = 115200;
    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(USART2, &USART_InitStructure);
    
    // Enable USART2 DMA RX request
    USART_DMACmd(USART2, USART_DMAReq_Rx, ENABLE);
    
    // DMA1 Stream5 Channel4 configuration
    DMA_InitStructure.DMA_Channel = DMA_Channel_4;
    DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralToMemory;
    DMA_InitStructure.DMA_Memory0BaseAddr = (uint32_t)rx_buffer[0];
    DMA_InitStructure.DMA_BufferSize = RX_BUFFER_SIZE;
    DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t)&(USART2->DR);
    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_Circular;
    DMA_InitStructure.DMA_Priority = DMA_Priority_High;
    DMA_InitStructure.DMA_FIFOMode = DMA_FIFOMode_Disable;
    DMA_InitStructure.DMA_FIFOThreshold = DMA_FIFOThreshold_HalfFull;
    DMA_InitStructure.DMA_MemoryBurst = DMA_MemoryBurst_Single;
    DMA_InitStructure.DMA_PeripheralBurst = DMA_PeripheralBurst_Single;
    DMA_Init(DMA1_Stream5, &DMA_InitStructure);
    
    // Enable DMA1 Stream5
    DMA_Cmd(DMA1_Stream5, ENABLE);
    
    // Enable USART2
    USART_Cmd(USART2, ENABLE);
}

void DMA1_Stream5_IRQHandler(void)
{
    if (DMA_GetITStatus(DMA1_Stream5, DMA_IT_TCIF5))
    {
        DMA_ClearITPendingBit(DMA1_Stream5, DMA_IT_TCIF5);
        
        // 切换到另一个缓冲区
        rx_index ^= 1;
        
        // 计算数据长度
        rx_length[rx_index] = RX_BUFFER_SIZE - DMA_GetCurrDataCounter(DMA1_Stream5);
    }
}

int main(void)
{
    USART2_Config();
    
    while (1)
    {
        // 处理接收到的数据
        if (rx_length[rx_index] > 0)
        {
            // 处理rx_buffer[rx_index][0]~rx_buffer[rx_index][rx_length[rx_index]-1]中的数据
            // ...
            
            // 清空缓冲区
            memset(rx_buffer[rx_index], 0, RX_BUFFER_SIZE);
            rx_length[rx_index] = 0;
        }
    }
}

这个代码中，使用了一个`rx_buffer`数组来实现乒乓缓冲区，由DMA控制器在两个缓冲区之间进行自动切换。当一个缓冲区中的数据接收完成后，会触发DMA中断，在中断处理函数中切换到另一个缓冲区，并计算出当前缓冲区中接收到的数据长度。在主函数中，可以通过判断`rx_length[rx_index]`是否大于0来判断是否有新的数据到来，然后对当前缓冲区中的数据进行处理，并清空缓冲区。