uart_sample.c

/* * Copyright (c) 2006-2018, RT-Thread Development Team * * SPDX-License-Identifier: Apache-2.0 * * Change Logs: * Date Author Notes * 2018-08-15 misonyo first implementation. *//* * 程序清单：这是一个 串口 设备使用例程 * 例程导出了 uart_sample 命令到控制终端 * 命令调用格式：uart_sample uart2 * 命令解释：命令第二个参数是要使用的串口设备名称，为空则使用默认的串口设备 * 程序功能：通过串口输出字符串"hello RT-Thread!"，然后错位输出输入的字符*/#include <rtthread.h>#define SAMPLE_UART_NAME "uart2" /* 串口设备名称 *//* 用于接收消息的信号量 */static struct rt_semaphore rx_sem;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){ /* 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 */ rt_sem_release(&rx_sem); return RT_EOK;}static void serial_thread_entry(void *parameter){ char ch; 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) { /* 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); }}static int uart_sample(int argc, char *argv[]){ rt_err_t ret = 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); } else { rt_strncpy(uart_name, SAMPLE_UART_NAME, RT_NAME_MAX); } /* 查找串口设备 */ 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 { ret = RT_ERROR; } return ret;}/* 导出到 msh 命令列表中 */MSH_CMD_EXPORT(uart_sample, uart device sample);