ESP32-C6（ESP-IDF）：UART1可接收字符但UART0无法接收

在ESP32-C6-DevKitC-1开发板上使用ESP-IDF开发基础UART通信，基于wifi/scan示例开发。UART1通过GPIO10、11可正常收发数据，但切换到UART0（默认GPIO16、17）时仅能发送数据，无法接收。代码仅修改了UART编号与引脚设置，连接的是官方引脚定义对应的引脚，请问故障原因是什么？

可用的UART1初始化及读取代码 #

void UART_Initialize_WorksOn10and11()
{
    uart_config_t uart_config = {
        .baud_rate = 115200,
        .data_bits = UART_DATA_8_BITS,
        .parity    = UART_PARITY_DISABLE,
        .stop_bits = UART_STOP_BITS_1,
        .flow_ctrl = UART_HW_FLOWCTRL_DISABLE,
        .source_clk = UART_SCLK_DEFAULT,
    };

    SMILE_UART_NUM = UART_NUM_1;

    esp_err_t r;

    const int uart_buffer_size = (1024 * 2);
    QueueHandle_t uart_queue;

    r = uart_driver_install(SMILE_UART_NUM, uart_buffer_size, uart_buffer_size, 10, NULL, 0);
    r = uart_param_config(SMILE_UART_NUM, &uart_config);
    r = uart_set_pin(SMILE_UART_NUM, 11,10, UART_PIN_NO_CHANGE, UART_PIN_NO_CHANGE); 
}

void UART_ReadLoop()
{
    int reported_length = 0;
    esp_err_t r;
    r = uart_get_buffered_data_len(SMILE_UART_NUM, (size_t*)&reported_length);
    int bytes_to_read = reported_length;
    int bytes_read = uart_read_bytes(SMILE_UART_NUM, m_RxBuffer, reported_length, 0);

    if (bytes_read > 0)
    {
        printf("Read '%s'\n", m_RxBuffer);
    }
}

UART0初始化代码 #

void UART_Initialize_DoesntWorkOnUART0()
{   
    uart_config_t uart_config = {
        .baud_rate = 115200,
        .data_bits = UART_DATA_8_BITS,
        .parity    = UART_PARITY_DISABLE,
        .stop_bits = UART_STOP_BITS_1,
        .flow_ctrl = UART_HW_FLOWCTRL_DISABLE,
        .source_clk = UART_SCLK_DEFAULT,
    };


    SMILE_UART_NUM = UART_NUM_0;  // *** CHANGED FOR UART0
    esp_err_t r;
    const int uart_buffer_size = (1024 * 2);
    QueueHandle_t uart_queue;

    r = uart_driver_install(SMILE_UART_NUM, uart_buffer_size, uart_buffer_size, 10, NULL, 0);
    r = uart_param_config(SMILE_UART_NUM, &uart_config);
    r = uart_set_pin(SMILE_UART_NUM, UART_PIN_NO_CHANGE,UART_PIN_NO_CHANGE, UART_PIN_NO_CHANGE, UART_PIN_NO_CHANGE);    // *** CHANGED FOR UART0
}

故障原因及解决方案 #

核心原因 #

ESP32-C6的UART0默认被用作系统调试串口（控制台输出），ESP-IDF默认会占用UART0的Rx引脚（GPIO17）用于接收调试命令，或被系统日志/控制台功能抢占资源，导致用户代码无法正常读取该引脚的数据。此外，系统初始化阶段已对UART0的引脚和驱动做了配置，用户后续的初始化操作未完全覆盖默认设置，尤其是Rx通道的权限。

解决步骤 #

1. 禁用UART0的控制台功能
   打开项目配置（idf.py menuconfig），进入Component config -> ESP System Settings -> UART for console output，将其改为None或其他串口（如UART1），释放UART0的Rx引脚供用户代码使用。

2. 显式指定UART0引脚并重置驱动
   即使使用默认引脚，也建议显式调用uart_set_pin指定GPIO16（Tx）和GPIO17（Rx），并在安装新驱动前删除默认驱动，避免配置冲突。修改后的初始化代码如下：

   void UART_Initialize_DoesntWorkOnUART0()
   {   
       uart_config_t uart_config = {
           .baud_rate = 115200,
           .data_bits = UART_DATA_8_BITS,
           .parity    = UART_PARITY_DISABLE,
           .stop_bits = UART_STOP_BITS_1,
           .flow_ctrl = UART_HW_FLOWCTRL_DISABLE,
           .source_clk = UART_SCLK_DEFAULT,
       };
   
       SMILE_UART_NUM = UART_NUM_0;
       esp_err_t r;
       const int uart_buffer_size = (1024 * 2);
       QueueHandle_t uart_queue;
   
       // 先卸载系统默认的UART0驱动
       uart_driver_delete(SMILE_UART_NUM);
       r = uart_driver_install(SMILE_UART_NUM, uart_buffer_size, uart_buffer_size, 10, NULL, 0);
       r = uart_param_config(SMILE_UART_NUM, &uart_config);
       // 显式指定UART0的Tx和Rx引脚
       r = uart_set_pin(SMILE_UART_NUM, 16, 17, UART_PIN_NO_CHANGE, UART_PIN_NO_CHANGE);
   }
   

3. 硬件连接检查
   确认GPIO17的硬件连接无虚焊、短路，外部设备的Tx引脚电平与ESP32-C6的UART电平兼容（3.3V）。

内容的提问来源于stack exchange，提问作者Chris