change uart sample

Author: misonyo

uart_sample.c

@@ -21,7 +21,8 @@
 
 /* 用于接收消息的信号量 */
 static struct rt_semaphore rx_sem;
-static char uart_name[RT_NAME_MAX];
+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)
 {
@@ -34,43 +35,27 @@ static rt_err_t uart_input(rt_device_t dev, rt_size_t size)
 static void serial_thread_entry(void *parameter)
 {
     char ch;
-    rt_device_t serial;
-    char str[] = "hello RT-Thread!\r\n";
-
-    /* 查找系统中的串口设备 */
-    serial = rt_device_find(uart_name);
 
-    if (serial != RT_NULL)
+    while (1)
     {
-        rt_sem_init(&rx_sem, "rx_sem", 0, RT_IPC_FLAG_FIFO);
-        /* 以读写及中断接收方式打开串口设备 */
-        rt_device_open(serial, RT_DEVICE_OFLAG_RDWR | 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));
-
-        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)
         {
-            /* 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 */
-            ch = ch + 1;
-            rt_device_write(serial, 0, &ch, 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);
         }
-    }
-    else
-    {
-        rt_kprintf("uart sample run failed! can't find %s device!\n", uart_name);
+        /* 读取到的数据通过串口错位输出 */
+        ch = ch + 1;
+        rt_device_write(serial, 0, &ch, 1);
     }
 }
 
-static void uart_sample(int argc, char *argv[])
+static int uart_sample(int argc, char *argv[])
 {
+    rt_err_t res = RT_EOK;
+    char uart_name[RT_NAME_MAX];
+    char str[] = "hello RT-Thread!\r\n";
+
     if (argc == 2)
     {
         rt_strncpy(uart_name, argv[1], RT_NAME_MAX);
@@ -80,13 +65,36 @@ static void uart_sample(int argc, char *argv[])
         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;
+    }
+
+    /* 初始化信号量 */
+    rt_sem_init(&rx_sem, "rx_sem", 0, RT_IPC_FLAG_FIFO);
+    /* 以读写及中断接收方式打开串口设备 */
+    rt_device_open(serial, RT_DEVICE_OFLAG_RDWR | 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
+    {
+        res = RT_ERROR;
+    }
+
+    return res;
 }
 /* 导出到 msh 命令列表中 */
 MSH_CMD_EXPORT(uart_sample, uart device sample);