f405标准库串口DMA接收

要使用F405标准库实现串口DMA接收，需要按照以下步骤进行操作：

1. 配置串口GPIO引脚，设置串口参数（波特率、数据位、停止位、校验位等）。

2. 配置DMA，设置DMA通道和流，以及DMA传输方向和传输数据长度。

3. 使能DMA和串口接收中断，并设置中断优先级。

4. 在中断服务函数中处理DMA传输完成和串口接收中断，并将接收到的数据存储到缓冲区中。

以下是一个简单的代码示例，供参考：

#include "stm32f4xx_gpio.h"
#include "stm32f4xx_usart.h"
#include "stm32f4xx_dma.h"
#include "misc.h"

#define RX_BUFFER_SIZE 256

volatile uint8_t rx_buffer[RX_BUFFER_SIZE];
volatile uint32_t rx_index = 0;

void USART_Config(void)
{
    GPIO_InitTypeDef GPIO_InitStructure;
    USART_InitTypeDef USART_InitStructure;

    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE);
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_USART2, ENABLE);

    GPIO_PinAFConfig(GPIOA, GPIO_PinSource2, GPIO_AF_USART2);
    GPIO_PinAFConfig(GPIOA, GPIO_PinSource3, GPIO_AF_USART2);

    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_2 | GPIO_Pin_3;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
    GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP;
    GPIO_Init(GPIOA, &GPIO_InitStructure);

    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);

    USART_Cmd(USART2, ENABLE);
}

void DMA_Config(void)
{
    DMA_InitTypeDef DMA_InitStructure;

    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_DMA1, ENABLE);

    DMA_DeInit(DMA1_Stream5);

    DMA_InitStructure.DMA_Channel = DMA_Channel_4;
    DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t)&(USART2->DR);
    DMA_InitStructure.DMA_Memory0BaseAddr = (uint32_t)rx_buffer;
    DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralToMemory;
    DMA_InitStructure.DMA_BufferSize = RX_BUFFER_SIZE;
    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_Full;
    DMA_InitStructure.DMA_MemoryBurst = DMA_MemoryBurst_Single;
    DMA_InitStructure.DMA_PeripheralBurst = DMA_PeripheralBurst_Single;
    DMA_Init(DMA1_Stream5, &DMA_InitStructure);

    USART_DMACmd(USART2, USART_DMAReq_Rx, ENABLE);
    DMA_Cmd(DMA1_Stream5, ENABLE);
}

void NVIC_Config(void)
{
    NVIC_InitTypeDef NVIC_InitStructure;

    NVIC_PriorityGroupConfig(NVIC_PriorityGroup_2);

    NVIC_InitStructure.NVIC_IRQChannel = DMA1_Stream5_IRQn;
    NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
    NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
    NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
    NVIC_Init(&NVIC_InitStructure);

    NVIC_InitStructure.NVIC_IRQChannel = USART2_IRQn;
    NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 1;
    NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
    NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
    NVIC_Init(&NVIC_InitStructure);
}

void DMA1_Stream5_IRQHandler(void)
{
    if (DMA_GetITStatus(DMA1_Stream5, DMA_IT_TCIF5) != RESET)
    {
        DMA_ClearITPendingBit(DMA1_Stream5, DMA_IT_TCIF5);
    }
}

void USART2_IRQHandler(void)
{
    if (USART_GetITStatus(USART2, USART_IT_RXNE) != RESET)
    {
        USART_ClearITPendingBit(USART2, USART_IT_RXNE);

        if (rx_index < RX_BUFFER_SIZE)
        {
            rx_buffer[rx_index++] = USART_ReceiveData(USART2);
        }
        else
        {
            rx_index = 0;
        }
    }
}

int main(void)
{
    USART_Config();
    DMA_Config();
    NVIC_Config();

    while (1)
    {
        // Do something
    }
}

在上述代码中，串口使用的是USART2，DMA使用的是DMA1的第5个流。接收到的数据存储在rx_buffer数组中，rx_index变量表示当前存储的数据位置。DMA传输完成和串口接收中断分别在DMA1_Stream5_IRQHandler和USART2_IRQHandler中处理。需要注意的是，当接收到的数据长度超过了缓冲区长度时，需要将rx_index变量重置为0，以便下一次接收。