USART串口_第三课

串口发送与接收

1、阻塞式发送

1.1、练习receive() 和Transmit()

测试1：测试接收发送函数 receive() 和 Transmit()

在main()中写入测试代码：将stm32接收的代码，再发送到调试助手

uint8_t buf[5];
void main(){
    while(1){
        //参数：huart1句柄，接收区首地址，传输字节数，超时时间
		HAL_UART_Receive(&huart1, buf,5,0xFFFF);//在stm32接收
        HAL_UART_Transmit(&huart1, buf,5,0xFFFF);//从stm32发出
    }
}

1.2、printf()重定向

main.c写入代码，用printf重定向到调试工具，将stm32接收的代码，再发送到调试助手。

//重定向 printf
#include <stdio.h>

#ifdef __GNUC__
#define PUTCHAR_PROTOTYPE int __io_putchar(int ch)
#define GETCHAR_PROTOTYPE int __io_getchar(void)
#else
#define PUTCHAR_PROTOTYPE int fputc(int ch, FILE *f)
#define GETCHAR_PROTOTYPE int fgetc(FILE *f)
#endif /* __GNUC__ */

PUTCHAR_PROTOTYPE {
    HAL_UART_Transmit(&huart1, (uint8_t *) &ch, 1, 0xFFFF);
    return ch;
}
GETCHAR_PROTOTYPE {
    uint8_t ch = 0;
    HAL_UART_Receive(&huart1, (uint8_t *) &ch, 1, 0xFFFF);
    return __io_putchar(ch);
}

void main(){
    while(){
        int val=0;
        printf("\r\n 请输入一个数字：");
        scanf("%d", &val);
        printf("%d \r\n",val);
    }
}

2、非阻塞发送

配置一下CubeMX环境

• SYS->serial wire
• RCC->Crystal/Ceramic Resonator
• NVIC->enable USART global interrupt
• USART1->dma:具体如下图

DMA+空闲中断实现不定长接收

实现功能：发送3个单位以内的数据，返回给串口调试助手

main.c

uint8_t buffer[5];//接收区
void SystemClock_Config();
int main() {
    HAL_Init();
    SystemClock_Config();
    MX_DMA_Init();
    MX_USART1_UART_Init();
    HAL_UART_Receive_DMA(&huart1, buffer, 3);//开启接收
    __HAL_UART_ENABLE_IT(&huart1, UART_IT_IDLE);//空闲中断
    while (1) {
    }

    void SystemClock_Config() {//TODO
    void Error_Handler() {//TODO
}

dma.c

#include "dma.h"
void MX_DMA_Init(void){

  /* DMA controller clock enable */
  __HAL_RCC_DMA1_CLK_ENABLE();

  /* DMA interrupt init */
  /* DMA1_Channel4_IRQn interrupt configuration */
  HAL_NVIC_SetPriority(DMA1_Channel4_IRQn, 0, 0);
  HAL_NVIC_EnableIRQ(DMA1_Channel4_IRQn);
  /* DMA1_Channel5_IRQn interrupt configuration */
  HAL_NVIC_SetPriority(DMA1_Channel5_IRQn, 0, 0);
  HAL_NVIC_EnableIRQ(DMA1_Channel5_IRQn);

}

usart.c

#include "usart.h"
UART_HandleTypeDef huart1;
DMA_HandleTypeDef hdma_usart1_rx;
DMA_HandleTypeDef hdma_usart1_tx;

void MX_USART1_UART_Init(void) {

    huart1.Instance = USART1;
    huart1.Init.BaudRate = 115200;
    huart1.Init.WordLength = UART_WORDLENGTH_8B;
    huart1.Init.StopBits = UART_STOPBITS_1;
    huart1.Init.Parity = UART_PARITY_NONE;
    huart1.Init.Mode = UART_MODE_TX_RX;
    huart1.Init.HwFlowCtl = UART_HWCONTROL_NONE;
    huart1.Init.OverSampling = UART_OVERSAMPLING_16;
    if (HAL_UART_Init(&huart1) != HAL_OK) {
        Error_Handler();
    }
}

void HAL_UART_MspInit(UART_HandleTypeDef *uartHandle) {

    GPIO_InitTypeDef GPIO_InitStruct = {0};
    if (uartHandle->Instance == USART1) {

        /* USART1 clock enable */
        __HAL_RCC_USART1_CLK_ENABLE();

        __HAL_RCC_GPIOA_CLK_ENABLE();
        /**USART1 GPIO Configuration
        PA9     ------> USART1_TX
        PA10     ------> USART1_RX
        */
        GPIO_InitStruct.Pin = GPIO_PIN_9;
        GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
        GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_HIGH;
        HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);

        GPIO_InitStruct.Pin = GPIO_PIN_10;
        GPIO_InitStruct.Mode = GPIO_MODE_INPUT;
        GPIO_InitStruct.Pull = GPIO_PULLUP;
        HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);

        /* USART1 DMA Init */
        /* USART1_RX Init */
        hdma_usart1_rx.Instance = DMA1_Channel5;
        hdma_usart1_rx.Init.Direction = DMA_PERIPH_TO_MEMORY;
        hdma_usart1_rx.Init.PeriphInc = DMA_PINC_DISABLE;
        hdma_usart1_rx.Init.MemInc = DMA_MINC_ENABLE;
        hdma_usart1_rx.Init.PeriphDataAlignment = DMA_PDATAALIGN_BYTE;
        hdma_usart1_rx.Init.MemDataAlignment = DMA_MDATAALIGN_BYTE;
        hdma_usart1_rx.Init.Mode = DMA_NORMAL;
        hdma_usart1_rx.Init.Priority = DMA_PRIORITY_LOW;
        if (HAL_DMA_Init(&hdma_usart1_rx) != HAL_OK) {
            Error_Handler();
        }

        __HAL_LINKDMA(uartHandle, hdmarx, hdma_usart1_rx);

        /* USART1_TX Init */
        hdma_usart1_tx.Instance = DMA1_Channel4;
        hdma_usart1_tx.Init.Direction = DMA_MEMORY_TO_PERIPH;
        hdma_usart1_tx.Init.PeriphInc = DMA_PINC_DISABLE;
        hdma_usart1_tx.Init.MemInc = DMA_MINC_ENABLE;
        hdma_usart1_tx.Init.PeriphDataAlignment = DMA_PDATAALIGN_BYTE;
        hdma_usart1_tx.Init.MemDataAlignment = DMA_MDATAALIGN_BYTE;
        hdma_usart1_tx.Init.Mode = DMA_NORMAL;
        hdma_usart1_tx.Init.Priority = DMA_PRIORITY_LOW;
        if (HAL_DMA_Init(&hdma_usart1_tx) != HAL_OK) {
            Error_Handler();
        }

        __HAL_LINKDMA(uartHandle, hdmatx, hdma_usart1_tx);

        /* USART1 interrupt Init */
        HAL_NVIC_SetPriority(USART1_IRQn, 1, 0);
        HAL_NVIC_EnableIRQ(USART1_IRQn);
    }
}

stm32f1xx_it.c 添加如下代码，作用是：当发送数据没有充满时但状态为空闲，则立即发送数据而不是等待填充满再发送

void USART1_IRQHandler(void) {

    //串口1的中断服务函数，判断是否为空闲状态
    if (__HAL_UART_GET_FLAG(&huart1, UART_FLAG_IDLE) != RESET) {
        __HAL_UART_CLEAR_IDLEFLAG(&huart1);
        HAL_UART_DMAStop(&huart1);
        uint8_t len = 3 - __HAL_DMA_GET_COUNTER(huart1.hdmarx);
        HAL_UART_Transmit_DMA(&huart1, buffer, len);
        HAL_UART_Receive_DMA(&huart1, buffer, 3);
    }

    HAL_UART_IRQHandler(&huart1);

}