[经验]

RTThread串口不定长接收的功能实现

2022-11-1 11:37:58

1321 RTThread 回调函数

之前做过DMA加串口空闲中断的方式接收不定长数据，想移植过来，但是那样的话就用不上rtthread自带的信号量这个内容了，于是基于信号量做了一个不定长接收的功能，基本思路是用两个字节间的时间间隔来做区分两帧的依据，用信号量好处不用另外开定时器，代码如下：

#define SAMPLE_UART4_NAME "uart4" /* 需要操作的设备 /
static struct rt_semaphore rx_sem4; / 信号量 /
static rt_device_t serial4; / 设备句柄 */

/* 接收数据回调函数 /
static rt_err_t uart4_rx_ind(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 */
if (size > 0)
{
rt_sem_release(&rx_sem4);
}
return RT_EOK;
}

static char uart_ZIGBEE_get_char(void)
{
char ch;
static uint8_t rv_flag = 1;

while (rt_device_read(serial4, 0, &ch, 1) == 0)
{
    rt_sem_control(&rx_sem4, RT_IPC_CMD_RESET, RT_NULL);
    if(rv_flag)
        rt_sem_take(&rx_sem4, RT_WAITING_FOREVER);
    else if(-RT_ETIMEOUT == rt_sem_take(&rx_sem4, 100))//超时100ms未获得串口数据  100是根据时钟节拍来定 节拍单位是1/RT_TICK_PER_SECOND 秒
    {
        rv_flag = 1; //收完一帧
        ch = '\n'; //也可以用别的当伪帧尾
        return ch;
    }
}
rv_flag = 0; //正常获取一个字节
return ch;

}

/* 数据解析线程 */
static void ZIGBEE_data_parsing(void)
{
char rx_temp = 0, rx_len = 0;
char data_buf[30] = {0};

while (1)
{
    rx_temp = uart_ZIGBEE_get_char();
    if(rx_temp != '\n')
    {
        data_buf[(rx_len++) % 30] = rx_temp;//防止数组越界
    }
    else //开始处理一帧数据
    {
        rx_len = 0;
        rt_kprintf("uart4 received data is %s\n", data_buf);
        /* 帧数据处理 */
        memset(data_buf, 0, sizeof(data_buf));
    }
}

}

static int uart4_ZIGBEE(void)
{
rt_err_t ret = RT_EOK;
/* 查找系统中的串口设备 /
serial4 = rt_device_find(SAMPLE_UART4_NAME);
if (!serial4)
{
rt_kprintf("find %s failed!\n", SAMPLE_UART4_NAME);
return RT_ERROR;
}
/ 初始化信号量 /
rt_sem_init(&rx_sem4, "rx_sem4", 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(serial4, RT_DEVICE_FLAG_INT_RX);
/ 设置接收回调函数 */
rt_device_set_rx_indicate(serial4, uart4_rx_ind);

/* 创建 serial 线程 */
rt_thread_t thread = rt_thread_create("ZIG_th", (void (*)(void *parameter))ZIGBEE_data_parsing,
                                       RT_NULL, 512, RT_THREAD_PRIORITY_MAX-10, 10);
/* 创建成功则启动线程 */
if (thread != RT_NULL)
{
    rt_thread_startup(thread);
}
else
{
    ret = RT_ERROR;
}

return ret;