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+/*
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+ * Copyright (c) 2006-2018, RT-Thread Development Team
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+ *
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+ * SPDX-License-Identifier: Apache-2.0
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+ *
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+ * Change Logs:
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+ * Date Author Notes
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+ * 2019-04-16 misonyo first implementation.
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+ */
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+/*
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+ * 程序清单：这是一个串口设备 DMA 接收使用例程
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+ * 例程导出了 uart_dma_sample 命令到控制终端
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+ * 命令调用格式：uart_dma_sample uart3
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+ * 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
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+ * 程序功能：通过串口输出字符串"hello RT-Thread!"，并通过串口输出接收到的数据，然后打印接收到的数据。
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+*/
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+
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+#include <rtthread.h>
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+
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+#define SAMPLE_UART_NAME "uart3" /* 串口设备名称 */
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+
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+/* 串口接收消息结构*/
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+struct rx_msg
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+{
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+ rt_device_t dev;
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+ rt_size_t size;
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+};
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+/* 串口设备句柄 */
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+static rt_device_t serial;
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+/* 消息队列控制块 */
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+static struct rt_messagequeue rx_mq;
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+
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+/* 接收数据回调函数 */
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+static rt_err_t uart_input(rt_device_t dev, rt_size_t size)
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+{
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+ struct rx_msg msg;
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+ rt_err_t result;
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+ msg.dev = dev;
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+ msg.size = size;
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+
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+ result = rt_mq_send(&rx_mq, &msg, sizeof(msg));
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+ if ( result == -RT_EFULL)
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+ {
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+ /* 消息队列满 */
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+ rt_kprintf("message queue full！\n");
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+ }
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+ return result;
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+}
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+
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+static void serial_thread_entry(void *parameter)
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+{
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+ struct rx_msg msg;
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+ rt_err_t result;
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+ rt_uint32_t rx_length;
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+ static char rx_buffer[RT_SERIAL_RB_BUFSZ + 1];
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+
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+ while (1)
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+ {
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+ rt_memset(&msg, 0, sizeof(msg));
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+ /* 从消息队列中读取消息*/
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+ result = rt_mq_recv(&rx_mq, &msg, sizeof(msg), RT_WAITING_FOREVER);
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+ if (result == RT_EOK)
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+ {
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+ /* 从串口读取数据*/
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+ rx_length = rt_device_read(msg.dev, 0, rx_buffer, msg.size);
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+ rx_buffer[rx_length] = '\0';
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+ /* 通过串口设备 serial 输出读取到的消息 */
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+ rt_device_write(serial, 0, rx_buffer, rx_length);
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+ /* 打印数据 */
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+ rt_kprintf("%s\n",rx_buffer);
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+ }
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+ }
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+}
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+
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+static int uart_dma_sample(int argc, char *argv[])
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+{
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+ rt_err_t ret = RT_EOK;
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+ char uart_name[RT_NAME_MAX];
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+ static char msg_pool[256];
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+ char str[] = "hello RT-Thread!\r\n";
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+
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+ if (argc == 2)
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+ {
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+ rt_strncpy(uart_name, argv[1], RT_NAME_MAX);
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+ }
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+ else
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+ {
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+ rt_strncpy(uart_name, SAMPLE_UART_NAME, RT_NAME_MAX);
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+ }
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+
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+ /* 查找串口设备 */
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+ serial = rt_device_find(uart_name);
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+ if (!serial)
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+ {
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+ rt_kprintf("find %s failed!\n", uart_name);
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+ return RT_ERROR;
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+ }
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+
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+ /* 初始化消息队列 */
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+ rt_mq_init(&rx_mq, "rx_mq",
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+ msg_pool, /* 存放消息的缓冲区 */
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+ sizeof(struct rx_msg), /* 一条消息的最大长度 */
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+ sizeof(msg_pool), /* 存放消息的缓冲区大小 */
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+ 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 */
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+
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+ /* 以 DMA 接收及轮询发送方式打开串口设备 */
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+ rt_device_open(serial, RT_DEVICE_FLAG_DMA_RX);
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+ /* 设置接收回调函数 */
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+ rt_device_set_rx_indicate(serial, uart_input);
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+ /* 发送字符串 */
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+ rt_device_write(serial, 0, str, (sizeof(str) - 1));
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+
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+ /* 创建 serial 线程 */
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+ rt_thread_t thread = rt_thread_create("serial", serial_thread_entry, RT_NULL, 1024, 25, 10);
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+ /* 创建成功则启动线程 */
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+ if (thread != RT_NULL)
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+ {
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+ rt_thread_startup(thread);
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+ }
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+ else
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+ {
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+ ret = RT_ERROR;
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+ }
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+
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+ return ret;
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+}
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+/* 导出到 msh 命令列表中 */
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+MSH_CMD_EXPORT(uart_dma_sample, uart device dma sample);
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