rt-thread中Uart停止位设置求助

发布于 2022-08-03 13:08:09 浏览：575 订阅该版

crystal266 2022-08-03

嵌入式

什么单片机？按照下面这样进行设置，不过STM32的RTT库和HAL库只支持1个或2个停止位。
```c
struct serial_configure config = RT_SERIAL_CONFIG_DEFAULT;  // 初始化配置参数 115200 8n1
rt_device_t serial;

serial = rt_device_find("uart2");
rt_device_open(serial, RT_DEVICE_FLAG_INT_RX);

config.stop_bits = STOP_BITS_1; // 设置停止位，目前STM32只支持1个或2个停止位
rt_device_control(serial;, RT_DEVICE_CTRL_CONFIG, &config);  // 控制串口设备参数
```

在文件 drivers\drv_usart.c 中的 `switch (cfg->stop_bits)` 部分限制了停止位的取值范围，如下所示
```c
static rt_err_t stm32_configure(struct rt_serial_device *serial, struct serial_configure *cfg)
{
    struct stm32_uart *uart;
    RT_ASSERT(serial != RT_NULL);
    RT_ASSERT(cfg != RT_NULL);

uart = rt_container_of(serial, struct stm32_uart, serial);

/* uart clock enable */
    stm32_uart_clk_enable(uart->config);
    /* uart gpio clock enable and gpio pin init */
    stm32_gpio_configure(uart->config);

uart->handle.Instance          = uart->config->Instance;
    uart->handle.Init.BaudRate     = cfg->baud_rate;
    uart->handle.Init.HwFlowCtl    = UART_HWCONTROL_NONE;
    uart->handle.Init.Mode         = UART_MODE_TX_RX;
    uart->handle.Init.OverSampling = UART_OVERSAMPLING_16;
    switch (cfg->data_bits)
    {
    case DATA_BITS_8:
        uart->handle.Init.WordLength = UART_WORDLENGTH_8B;
        break;
    case DATA_BITS_9:
        uart->handle.Init.WordLength = UART_WORDLENGTH_9B;
        break;
    default:
        uart->handle.Init.WordLength = UART_WORDLENGTH_8B;
        break;
    }
    switch (cfg->stop_bits)
    {
    case STOP_BITS_1:
        uart->handle.Init.StopBits   = UART_STOPBITS_1;
        break;
    case STOP_BITS_2:
        uart->handle.Init.StopBits   = UART_STOPBITS_2;
        break;
    default:
        uart->handle.Init.StopBits   = UART_STOPBITS_1;
        break;
    }
    switch (cfg->parity)
    {
    case PARITY_NONE:
        uart->handle.Init.Parity     = UART_PARITY_NONE;
        break;
    case PARITY_ODD:
        uart->handle.Init.Parity     = UART_PARITY_ODD;
        break;
    case PARITY_EVEN:
        uart->handle.Init.Parity     = UART_PARITY_EVEN;
        break;
    default:
        uart->handle.Init.Parity     = UART_PARITY_NONE;
        break;
    }

if (HAL_UART_Init(&uart->handle) != HAL_OK)
    {
        return -RT_ERROR;
    }

return RT_EOK;
}
```

如果使用1.5个停止位需要自己修改一下源码，将1.5个停止位的代码加上。加在 `switch (cfg->stop_bits)` 部分。也可以参考 https://club.rt-thread.org/ask/question/9c58f5f6d6eb064b.html

![screenshot_image.png](https://oss-club.rt-thread.org/uploads/20220803/f3ac0ecc6cc5cef2802b4986477c62be.png)

```c
/** @defgroup UART_Stop_Bits UART Number of Stop Bits
  * @{
  */
#define UART_STOPBITS_1                     0x00000000U
#define UART_STOPBITS_2                     ((uint32_t)USART_CR2_STOP_1)
```