UART修改波特率后发送失败

发布于 2025-12-05 10:10:17 浏览：140 订阅该版

```c
#include <rtthread.h>

#define SAMPLE_UART_NAME "uart2"

/* 用于接收消息的信号量 */
static struct rt_semaphore rx_sem;
static rt_device_t serial;

/* 接收数据回调函数 */
static rt_err_t uart_input(rt_device_t dev, rt_size_t size)
{
    /* 串口接收到数据后产生中断，调用此回调函数，然后发送接收信号量 */
    rt_sem_release(&rx_sem);

return RT_EOK;
}

static void serial_thread_entry(void *parameter)
{
    char ch;
    rt_ssize_t size;
    rt_pin_write(MODBUS_MASTER_RT_CONTROL_PIN_INDEX, PIN_HIGH);
    while (1)
    {
        /* 从串口读取一个字节的数据，没有读取到则等待接收信号量 */
        //        while (rt_device_read(serial, -1, &ch, 1) != 1)
        //        {
        //            /* 阻塞等待接收信号量，等到信号量后再次读取数据 */
        //            rt_sem_take(&rx_sem, RT_WAITING_FOREVER);
        //        }
        /* 读取到的数据通过串口错位输出 */
        // printf("%02X  ", ch);

size = rt_device_write(serial, 0, (uint8_t[]){0xaa, 0x55, 0x5a, 0xa5}, 4);
        printf("size:%d\n",size);
        rt_thread_mdelay(100);
        //        rt_pin_write(MODBUS_MASTER_RT_CONTROL_PIN_INDEX, PIN_LOW);
    }
}

static int uart_sample(void)
{
    rt_err_t ret = RT_EOK;
    char uart_name[RT_NAME_MAX];
    char str[] = "hello RT-Thread!\r\n";
    struct serial_configure config = RT_SERIAL_CONFIG_DEFAULT;

rt_strncpy(uart_name, SAMPLE_UART_NAME, RT_NAME_MAX);

/* 查找系统中的串口设备 */
    serial = rt_device_find(uart_name);
    if (!serial)
    {
        rt_kprintf("find %s failed!\n", uart_name);
        return RT_ERROR;
    }
    rt_pin_mode(MODBUS_MASTER_RT_CONTROL_PIN_INDEX, PIN_MODE_OUTPUT);

/* 初始化信号量 */
    rt_sem_init(&rx_sem, "rx_sem", 0, RT_IPC_FLAG_FIFO);

config.baud_rate = BAUD_RATE_115200;
    config.stop_bits = STOP_BITS_1;
    config.data_bits = DATA_BITS_9;
    config.parity = PARITY_EVEN;

ret = rt_device_control(serial, RT_DEVICE_CTRL_CONFIG, &config);
    printf("1ret:%d\n", ret);
    /* 以中断接收及轮询发送模式打开串口设备 */
    ret = rt_device_open(serial, RT_DEVICE_FLAG_INT_RX);
    printf("1open:%d\n", ret);

rt_device_control(serial, RT_DEVICE_CTRL_CONFIG, &config);
    printf("2ret:%d\n", ret);
    ret = rt_device_open(serial, RT_DEVICE_FLAG_INT_RX);
    printf("2open:%d\n", ret);
    /* 设置接收回调函数 */
    rt_device_set_rx_indicate(serial, uart_input);

/* 发送字符串 */
    rt_pin_write(MODBUS_MASTER_RT_CONTROL_PIN_INDEX, PIN_HIGH);
    rt_device_write(serial, 0, str, (sizeof(str) - 1));
    rt_thread_mdelay(5);
    rt_pin_write(MODBUS_MASTER_RT_CONTROL_PIN_INDEX, PIN_LOW);
    /* 创建 serial 线程 */
    rt_thread_t thread = rt_thread_create("serial", serial_thread_entry, RT_NULL, 1024, 25, 10);
    /* 创建成功则启动线程 */
    if (thread != RT_NULL)
    {
        rt_thread_startup(thread);
    }
    else
    {
        ret = RT_ERROR;
    }
    return 0;
}
/* 导出到 msh 命令列表中 */
INIT_APP_EXPORT(uart_sample);
```
修改这段代码为后 发送失败，返回值为0，波特率在115200时发送正常
```c
config.baud_rate = BAUD_RATE_9600;
```
软件版本为5.2.1