RT-Thread-关于官网《I/O设备管理》中的串口设备操作例程的思考RT-Thread问答社区

关于官网《I/O设备管理》中的串口设备操作例程的思考

发布于 2018-07-12 22:24:50 浏览：2595 订阅该版

* 本帖最后由 武汉有为物联网 于 2018-7-12 22:36 编辑 *

先上官方代码
```/*
 * 程序清单：串口设备操作例程
 *
 * 在这个例程中，将启动一个devt线程，然后打开串口1和2
 * 当串口1和2有输入时，将读取其中的输入数据然后写入到
 * 串口1设备中。
 *
 */
#include <rtthread.h>

/* UART接收消息结构*/
struct rx_msg
{
    rt_device_t dev;
    rt_size_t size;
};
/* 用于接收消息的消息队列*/
static rt_mq_t rx_mq;
/* 接收线程的接收缓冲区*/
static char uart_rx_buffer[64];

/* 数据到达回调函数*/
rt_err_t uart_input(rt_device_t dev, rt_size_t size)
{
    struct rx_msg msg;
    msg.dev = dev;
    msg.size = size;

/* 发送消息到消息队列中*/
    rt_mq_send(rx_mq, &msg, sizeof(struct rx_msg));

return RT_EOK;
}

void device_thread_entry(void* parameter)
{
    struct rx_msg msg;
    int count = 0;
    rt_device_t device, write_device;
    rt_err_t result = RT_EOK;

/* 查找系统中的串口1设备 */
    device = rt_device_find("uart1");
    if (device!= RT_NULL)
    {
        /* 设置回调函数及打开设备*/
        rt_device_set_rx_indicate(device, uart_input);
        rt_device_open(device, RT_DEVICE_OFLAG_RDWR|RT_DEVICE_FLAG_INT_RX);
    }
    /* 设置写设备为uart1设备 */
    write_device = device;

/* 查找系统中的串口2设备 */
    device= rt_device_find("uart2");
    if (device_!= RT_NULL)
    {
        /* 设置回调函数及打开设备*/
        rt_device_set_rx_indicate(device, uart_input);
        rt_device_open(device, RT_DEVICE_OFLAG_RDWR);
    }

while (1)
 {
 /* 从消息队列中读取消息*/
 result = rt_mq_recv(rx_mq, &msg, sizeof(struct rx_msg), 50);
 if (result == -RT_ETIMEOUT)
 {
 /* 接收超时*/
 rt_kprintf("timeout count:%d ", ++count);
 }

/* 成功收到消息*/
        if (result == RT_EOK)
        {
            rt_uint32_t rx_length;
            rx_length = (sizeof(uart_rx_buffer) - 1) > msg.size ?
                    msg.size : sizeof(uart_rx_buffer) - 1;

/* 读取消息*/
            rx_length = rt_device_read(msg.dev, 0, &uart_rx_buffer[0],
                    rx_length);
            uart_rx_buffer[rx_length] = '\0';

/* 写到写设备中*/
            if (write_device != RT_NULL)
                rt_device_write(write_device, 0, &uart_rx_buffer[0],
                        rx_length);
        }
    }
}

int rt_application_init()
{
    /* 创建devt线程*/
    rt_thread_t thread = rt_thread_create("devt",
        device_thread_entry, RT_NULL,
        1024, 25, 7);
    /* 创建成功则启动线程*/
    if (thread!= RT_NULL)
        rt_thread_startup(thread);
}```

将上述例子 拷贝到  application.c 文件中 编译出现错误
applications/application.c(55): error:  #20: identifier "device_" is undefined
检查发现第55行代码 
 if (device_!= RT_NULL) 
有问题将 “device_”改为“device”后编译正常，将代码在模拟状态下运行，出现 
\ | /- RT -     Thread Operating System
 / | \     3.0.3 build Jul 10 2018 2006 - 2018 Copyright by 
rt-thread team(mq != RT_NULL) assertion failed at function:rt_mq_recv, line number:2111 
有一个错误，作为新手没明白是啥原因出现错误停止运行  发现在这个 函数里面死循环了。
void rt_assert_handler(const char *ex_string, const char *func, rt_size_t line)

修改代码

```/*
 * 程序清单：串口设备操作例程
 *
 * 在这个例程中，将启动一个devt线程，然后打开串口1和2
 * 当串口1和2有输入时，将读取其中的输入数据然后写入到
 * 串口1设备中。
 *
 */
#include <rtthread.h>

/* UART接收消息结构*/
struct rx_msg
{
  rt_device_t dev;
  rt_size_t size;
};
/* 消息队列控制块 */
static struct rt_messagequeue mq;
  /* 消息队列中用到的放置消息的内存池 */

/* 数据到达回调函数*/
rt_err_t uart_input(rt_device_t dev, rt_size_t size)
{
 struct rx_msg msg;
 int result;
 char buf[] = "this is message No.x";
 msg.dev = dev;
 msg.size = size;
 /* 发送消息到消息队列中*/
 rt_kprintf("Receive From :%s ",dev->parent.name);
 /* 发送消息到消息队列中 */
 result = rt_mq_send(&mq, &msg, sizeof(msg));
 if ( result == -RT_EFULL)
 {
		/* 消息队列满， 延迟1s时间 */
		rt_kprintf("message queue full, delay 1s ");
		rt_thread_delay(1000);
 }
 return result;
}

void device_thread_entry(void* parameter)
{
  struct rx_msg msg;
  int count = 0;
  rt_device_t device, write_device;
  rt_err_t result = RT_EOK;
  static char uart_rx_buffer[64];

/* 查找系统中的串口1设备 */
  device = rt_device_find("uart1");
  if (device!= RT_NULL)
  {
    /* 设置回调函数及打开设备*/
    rt_device_set_rx_indicate(device, uart_input);
    rt_device_open(device, RT_DEVICE_OFLAG_RDWR|RT_DEVICE_FLAG_INT_RX);
  }
  /* 设置写设备为uart1设备 */
  write_device = device;

/* 查找系统中的串口2设备 */
  device= rt_device_find("uart2");
  if (device!= RT_NULL)
  {
    /* 设置回调函数及打开设备*/
    rt_device_set_rx_indicate(device, uart_input);
    rt_device_open(device, RT_DEVICE_OFLAG_RDWR|RT_DEVICE_FLAG_INT_RX);
  }

while (1)
 {
 /* 从消息队列中读取消息*/
		rt_memset(&msg, 0, sizeof(msg));
		result = rt_mq_recv(&mq, &msg, sizeof(msg), 50);
 if (result == -RT_ETIMEOUT)
 {
 /* 接收超时*/
 rt_kprintf("timeout count:%d ", ++count);
 }
 /* 从消息队列中接收消息 */
 if (result == RT_EOK)
 {
 rt_uint32_t rx_length;
 rx_length = (sizeof(uart_rx_buffer) - 1) > msg.size ?
 msg.size : sizeof(uart_rx_buffer) - 1;

/* 读取消息*/
 rx_length = rt_device_read(msg.dev, 0, &uart_rx_buffer[0],
 rx_length);
 uart_rx_buffer[rx_length] = '\0';
 rt_kprintf("Receive data:");
 /* 写到写设备中*/
 if (write_device != RT_NULL)
 rt_device_write(write_device, 0, &uart_rx_buffer[0],
 rx_length);
 rt_kprintf(" ");
 }
 }
}

int rt_application_init()
{
 static char msg_pool[2048];

/* 初始化消息队列 */
  rt_mq_init(&mq, "mqt",
             &msg_pool[0], /* 内存池指向msg pool */
             128 - sizeof(void*), /* 每个消息的大小是 128 - void* */
             sizeof(msg_pool), /* 内存池的大小是msg pool的大小 */
             RT_IPC_FLAG_FIFO); /* 如果有多个线程等待，按照先来先得到的方法分配消息 */

/* 创建devt线程*/
  rt_thread_t thread = rt_thread_create("devt",
                                        device_thread_entry, RT_NULL,
                                        2048, 25, 7);
  /* 创建成功则启动线程*/
  if (thread!= RT_NULL)
    rt_thread_startup(thread);

return 0;
}

```

运行代码  在串口1 和串口 2 中输入数据 出现如下显示信息 \ | /- RT -     Thread Operating System / | \     3.0.3 build Jul 10 2018 2006 - 2018 Copyright by rt-thread teamtimeout count:1timeout count:2timeout count:3Receive From :uart1Receive  data:2Receive From :uart1Receive  data:2Receive From :uart1Receive  data:2timeout count:4Receive From :uart2Receive  data:5Receive From :uart2Receive  data:5Receive From :uart2Receive  data:5Receive From :uart2Receive  data:5timeout count:5 timeout count  是没有发送数据是系统打印的时间计数。

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