2.ESP32之UART1串口的使用

本代码基于ESP-IDF 4.2 SDK编写，具体UART可参考官方例程

一、ESP32总共有3个串口，并且3个 串口管脚都是可以重映射的

1.串口收发代码编写

1.1加载串口相关的头文件、定义串口IO映射引脚、定义串口缓存等

/**
 * This is an example which echos any data it receives on UART1 back to the sender,
 * with hardware flow control turned off. It does not use UART driver event queue.
 *
 * - Port: UART1
 * - Pin assignment: see defines below
 */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "driver/uart.h"
#include "driver/gpio.h"
#include "cJSON.h"
#include "esp_log.h"
#include "sdkconfig.h"
#include "esp_system.h"
#include "esp_spi_flash.h"

#define EX_UART_NUM UART_NUM_1
#define ECHO_TEST_TXD (GPIO_NUM_4)
#define ECHO_TEST_RXD (GPIO_NUM_5)
#define BUF_SIZE (1024)

static const char *TAG = "UART1";

1.2串口初始化配置函数

void uart_init(void)
{
    //串口配置结构体
    uart_config_t uart_config = {
        .baud_rate = 9600,                     //波特率
        .data_bits = UART_DATA_8_BITS,         //数据位
        .parity = UART_PARITY_DISABLE,         //校验位
        .stop_bits = UART_STOP_BITS_1,         //停止位
        .flow_ctrl = UART_HW_FLOWCTRL_DISABLE, //流控位
        .source_clk = UART_SCLK_APB,
    };

    //设置串口
    uart_param_config(EX_UART_NUM, &uart_config);
    //IO映射->TX->GPIO_NUM_4,RX->GPIO_NUM_5
    uart_set_pin(EX_UART_NUM, ECHO_TEST_TXD, ECHO_TEST_RXD, UART_PIN_NO_CHANGE, UART_PIN_NO_CHANGE);
    //注册串口服务即使能+设置缓存区大小
    uart_driver_install(EX_UART_NUM, BUF_SIZE * 2, 0, 0, NULL, 0);
}

1.3 建立串口任务

static void echo_task(void *arg)
{
    //分配内存，用于串口接收
    uint8_t *data = (uint8_t *)malloc(BUF_SIZE);
    while (1)
    {
        // Read data from the UART
        int len = uart_read_bytes(EX_UART_NUM, data, BUF_SIZE, 20 / portTICK_RATE_MS);
        if (len > 0)
        {
            //在串口接收的数据增加结束符
            data[len] = 0;
            //将接收到的数据发出去
            uart_write_bytes(EX_UART_NUM, (const char *)data, len);
         }
    //释放申请的内存
    free(data);
    //删除任务
    vTaskDelete(NULL);
}

1.4 主函数：串口初始化、创建任务用于串口数据接收、测试串口发送数据

void app_main(void)
{
    uart_init(); //串口初始化
    //创建串口接收任务
    xTaskCreate(echo_task, "uart_echo_task", 1024, NULL, 10, NULL);
}