STM32F407通过按键触发外部中断，用DMA方式从串口1发送一个100字节的信息，按一次发一次

可以使用STM32F407的DMA和串口1模块来实现这个功能。首先，需要配置外部中断和DMA通道，以便在按键按下时触发DMA传输。然后，需要编写一个发送函数，将100字节的信息发送到串口1。最后，将发送函数与DMA通道关联，以便在DMA传输完成后自动调用发送函数。

以下是一个可能的实现：

#include "stm32f4xx.h"

#define BUFFER_SIZE 100

uint8_t buffer[BUFFER_SIZE];

void send_data(void) {
    // 发送数据到串口1
    for (int i = 0; i < BUFFER_SIZE; i++) {
        USART_SendData(USART1, buffer[i]);
        while (USART_GetFlagStatus(USART1, USART_FLAG_TXE) == RESET);
    }
}

int main(void) {
    // 初始化GPIO和外部中断
    GPIO_InitTypeDef GPIO_InitStruct;
    EXTI_InitTypeDef EXTI_InitStruct;
    NVIC_InitTypeDef NVIC_InitStruct;

    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE);
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_SYSCFG, ENABLE);

    GPIO_InitStruct.GPIO_Pin = GPIO_Pin_0;
    GPIO_InitStruct.GPIO_Mode = GPIO_Mode_IN;
    GPIO_InitStruct.GPIO_PuPd = GPIO_PuPd_UP;
    GPIO_Init(GPIOA, &GPIO_InitStruct);

    SYSCFG_EXTILineConfig(EXTI_PortSourceGPIOA, EXTI_PinSource0);

    EXTI_InitStruct.EXTI_Line = EXTI_Line0;
    EXTI_InitStruct.EXTI_Mode = EXTI_Mode_Interrupt;
    EXTI_InitStruct.EXTI_Trigger = EXTI_Trigger_Falling;
    EXTI_InitStruct.EXTI_LineCmd = ENABLE;
    EXTI_Init(&EXTI_InitStruct);

    NVIC_InitStruct.NVIC_IRQChannel = EXTI0_IRQn;
    NVIC_InitStruct.NVIC_IRQChannelPreemptionPriority = 0x00;
    NVIC_InitStruct.NVIC_IRQChannelSubPriority = 0x00;
    NVIC_InitStruct.NVIC_IRQChannelCmd = ENABLE;
    NVIC_Init(&NVIC_InitStruct);

    // 初始化DMA和串口1
    DMA_InitTypeDef DMA_InitStruct;
    USART_InitTypeDef USART_InitStruct;

    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_DMA2, ENABLE);
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1, ENABLE);

    DMA_InitStruct.DMA_Channel = DMA_Channel_4;
    DMA_InitStruct.DMA_PeripheralBaseAddr = (uint32_t)&USART1->DR;
    DMA_InitStruct.DMA_Memory0BaseAddr = (uint32_t)buffer;
    DMA_InitStruct.DMA_DIR = DMA_DIR_MemoryToPeripheral;
    DMA_InitStruct.DMA_BufferSize = BUFFER_SIZE;
    DMA_InitStruct.DMA_PeripheralInc = DMA_PeripheralInc_Disable;
    DMA_InitStruct.DMA_MemoryInc = DMA_MemoryInc_Enable;
    DMA_InitStruct.DMA_PeripheralDataSize = DMA_PeripheralDataSize_Byte;
    DMA_InitStruct.DMA_MemoryDataSize = DMA_MemoryDataSize_Byte;
    DMA_InitStruct.DMA_Mode = DMA_Mode_Normal;
    DMA_InitStruct.DMA_Priority = DMA_Priority_High;
    DMA_InitStruct.DMA_FIFOMode = DMA_FIFOMode_Disable;
    DMA_InitStruct.DMA_FIFOThreshold = DMA_FIFOThreshold_HalfFull;
    DMA_InitStruct.DMA_MemoryBurst = DMA_MemoryBurst_Single;
    DMA_InitStruct.DMA_PeripheralBurst = DMA_PeripheralBurst_Single;
    DMA_Init(DMA2_Stream7, &DMA_InitStruct);

    USART_InitStruct.USART_BaudRate = 115200;
    USART_InitStruct.USART_WordLength = USART_WordLength_8b;
    USART_InitStruct.USART_StopBits = USART_StopBits_1;
    USART_InitStruct.USART_Parity = USART_Parity_No;
    USART_InitStruct.USART_Mode = USART_Mode_Tx;
    USART_InitStruct.USART_HardwareFlowControl = USART_HardwareFlowControl_None;
    USART_Init(USART1, &USART_InitStruct);

    // 启动DMA和串口1
    DMA_Cmd(DMA2_Stream7, ENABLE);
    USART_Cmd(USART1, ENABLE);

    while (1) {
        // 等待外部中断触发
    }
}

void EXTI0_IRQHandler(void) {
    if (EXTI_GetITStatus(EXTI_Line0) != RESET) {
        // 外部中断触发，启动DMA传输
        DMA_Cmd(DMA2_Stream7, DISABLE);
        DMA_ClearFlag(DMA2_Stream7, DMA_FLAG_TCIF7);
        DMA_SetCurrDataCounter(DMA2_Stream7, BUFFER_SIZE);
        DMA_Cmd(DMA2_Stream7, ENABLE);
        EXTI_ClearITPendingBit(EXTI_Line0);
    }
}

请注意，此代码仅供参考，可能需要根据具体硬件和应用程序进行修改。