STM32F407使用标准库，串口USART2通过DMA进行数据接收使用乒乓缓冲的实例

好的，以下是使用标准库，串口USART2通过DMA进行数据接收使用乒乓缓冲的实例代码：

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

#define RX_BUFFER_SIZE 512

volatile uint8_t rx_buffer[2][RX_BUFFER_SIZE];
volatile uint32_t rx_write_index = 0;
volatile uint32_t rx_read_index = 0;
volatile uint32_t rx_count = 0;
volatile uint8_t rx_active_buffer = 0;

void init_usart(void);
void init_dma(void);
void DMA1_Stream5_IRQHandler(void);

int main(void)
{
    init_usart();
    init_dma();

    while (1) {
        if (rx_count > 0) {
            uint32_t i;
            for (i = 0; i < rx_count; i++) {
                printf("%c", rx_buffer[rx_read_index][i]);
            }
            rx_count = 0;
            rx_read_index = (rx_read_index + 1) % 2;
        }
    }
}

void init_usart(void)
{
    GPIO_InitTypeDef gpio_init;
    USART_InitTypeDef usart_init;

    // Enable GPIO clock
    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE);

    // Enable USART clock
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_USART2, ENABLE);

    // Configure USART pins
    gpio_init.GPIO_Pin = GPIO_Pin_2 | GPIO_Pin_3;
    gpio_init.GPIO_Mode = GPIO_Mode_AF;
    gpio_init.GPIO_Speed = GPIO_Speed_50MHz;
    gpio_init.GPIO_OType = GPIO_OType_PP;
    gpio_init.GPIO_PuPd = GPIO_PuPd_UP;
    GPIO_Init(GPIOA, &gpio_init);

    // Connect USART pins to AF
    GPIO_PinAFConfig(GPIOA, GPIO_PinSource2, GPIO_AF_USART2);
    GPIO_PinAFConfig(GPIOA, GPIO_PinSource3, GPIO_AF_USART2);

    // Configure USART
    usart_init.USART_BaudRate = 115200;
    usart_init.USART_WordLength = USART_WordLength_8b;
    usart_init.USART_StopBits = USART_StopBits_1;
    usart_init.USART_Parity = USART_Parity_No;
    usart_init.USART_HardwareFlowControl = USART_HardwareFlowControl_None;
    usart_init.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;
    USART_Init(USART2, &usart_init);

    // Enable USART
    USART_Cmd(USART2, ENABLE);
}

void init_dma(void)
{
    DMA_InitTypeDef dma_init;
    NVIC_InitTypeDef nvic_init;

    // Enable DMA clock
    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_DMA1, ENABLE);

    // Configure DMA channel
    DMA_DeInit(DMA1_Stream5);
    dma_init.DMA_Channel = DMA_Channel_4;
    dma_init.DMA_PeripheralBaseAddr = (uint32_t)&USART2->DR;
    dma_init.DMA_Memory0BaseAddr = (uint32_t)&rx_buffer[0];
    dma_init.DMA_DIR = DMA_DIR_PeripheralToMemory;
    dma_init.DMA_BufferSize = RX_BUFFER_SIZE;
    dma_init.DMA_PeripheralInc = DMA_PeripheralInc_Disable;
    dma_init.DMA_MemoryInc = DMA_MemoryInc_Enable;
    dma_init.DMA_PeripheralDataSize = DMA_PeripheralDataSize_Byte;
    dma_init.DMA_MemoryDataSize = DMA_MemoryDataSize_Byte;
    dma_init.DMA_Mode = DMA_Mode_Circular;
    dma_init.DMA_Priority = DMA_Priority_VeryHigh;
    dma_init.DMA_FIFOMode = DMA_FIFOMode_Disable;
    dma_init.DMA_FIFOThreshold = DMA_FIFOThreshold_1QuarterFull;
    dma_init.DMA_MemoryBurst = DMA_MemoryBurst_Single;
    dma_init.DMA_PeripheralBurst = DMA_PeripheralBurst_Single;
    DMA_Init(DMA1_Stream5, &dma_init);

    // Enable DMA interrupts
    DMA_ITConfig(DMA1_Stream5, DMA_IT_TC, ENABLE);
    nvic_init.NVIC_IRQChannel = DMA1_Stream5_IRQn;
    nvic_init.NVIC_IRQChannelPreemptionPriority = 0;
    nvic_init.NVIC_IRQChannelSubPriority = 0;
    nvic_init.NVIC_IRQChannelCmd = ENABLE;
    NVIC_Init(&nvic_init);

    // Start DMA transfer
    DMA_Cmd(DMA1_Stream5, ENABLE);
}

void DMA1_Stream5_IRQHandler(void)
{
    if (DMA_GetITStatus(DMA1_Stream5, DMA_IT_TCIF5)) {
        DMA_ClearITPendingBit(DMA1_Stream5, DMA_IT_TCIF5);

        // Swap active buffer
        rx_active_buffer = (rx_active_buffer + 1) % 2;

        // Set DMA memory buffer address
        DMA1_Stream5->M0AR = (uint32_t)&rx_buffer[rx_active_buffer];

        // Update write index and count
        uint32_t new_count = DMA_GetCurrDataCounter(DMA1_Stream5);
        rx_count += RX_BUFFER_SIZE - new_count;
        rx_write_index = rx_active_buffer;
    }
}

以上代码中使用了两个缓冲区，即“乒乓缓冲”。DMA接收数据到一个缓冲区时，另一个缓冲区可以被处理。在中断处理程序中，交换缓冲区并更新读写索引和计数器。在主循环中，如果有数据可用，则打印出来。

希望对你有所帮助！