用rt_device_write写uart3后却读不到数据

发布于 2021-11-30 17:01:16 浏览：1519 订阅该版

[tocm]

```c
static void serial_thread_entry(void *parameter)
{
    char ch_test;
		rt_kprintf("HQ enter serial_thread_entry\n ");
    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_test, 1) != 1)//**

### 此处一直读不到数据**

{
        		rt_kprintf("HQ rt_device_read\n");
            /* 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 */
        ch_test = ch_test + 1;
        rt_kprintf("HQ %d\n",ch_test);
        rt_device_write(serial, 0, &ch_test, 1);
    }
}

static int uart_sample(void)
{
    rt_err_t ret = RT_EOK;
    char uart_name[RT_NAME_MAX];
    char str[] = "hello RT-Thread!\r\n";
		rt_kprintf("HQ enter uart_sample\n ");

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

/* 初始化信号量 */
    rt_sem_init(&rx_sem, "rx_sem", 0, RT_IPC_FLAG_FIFO);
    /* 以中断接收及轮询发送模式打开串口设备 */
    rt_device_open(serial, RT_DEVICE_FLAG_INT_RX);
    /* 设置接收回调函数 */
    rt_device_set_rx_indicate(serial, uart_input);
    /* 发送字符串 */
    rt_device_write(serial, 0, str, (sizeof(str) - 1));

/* 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 ret;
}
```