Pandora loT使用uart3进行数据收发

1 引脚定义

潘多拉开发板预留了一些IO口供我们使用，其中便有PB10和PB11，其引脚功能查看数据手册如下：

使用USB转TTL将开发板连上电脑，下载口uart1也要连接

2 新建工程

打开RT-Studio，新建基于芯片STM32L475VETx的工程，下载口选择SWD.

3 修改配置

修改applications->main.c

#include <rtthread.h>
#include <board.h>
#include <rtdevice.h>

#define DBG_TAG "main"
#define DBG_LVL DBG_LOG
#include <rtdbg.h>

#define LED0_PIN  GET_PIN(E,8)

int main(void)
{
int count = 1;
rt_pin_mode(LED0_PIN, PIN_MODE_OUTPUT);
 LOG_D("System Clock information");
 LOG_D("SYSCLK_Frequency = %d", HAL_RCC_GetSysClockFreq());
 LOG_D("HCLK_Frequency   = %d", HAL_RCC_GetHCLKFreq());
 LOG_D("PCLK1_Frequency  = %d", HAL_RCC_GetPCLK1Freq());
 LOG_D("PCLK2_Frequency  = %d", HAL_RCC_GetPCLK2Freq());
while (count++)
{
    rt_pin_write(LED0_PIN, count % 2);
//        LOG_D("Hello RT-Thread!");
    rt_thread_mdelay(1000);
}

return RT_EOK;
}

这一步修改完之后，保存编译下载，可以看到绿灯闪烁

打开drivers->board.h，在其中添加uart3的引脚配置，并使能usat3，如下：

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#define BSP_USING_UART3
#define BSP_UART3_TX_PIN       "PB10"
#define BSP_UART3_RX_PIN       "PB11"
 修改时钟为外部时钟源

/*----- CLOCK CONFIG BEGIN --------*/

#define BSP_CLOCK_SOURCE           ("HSE")
#define BSP_CLOCK_SOURCE_FREQ_MHZ  ((int32_t)8)
#define BSP_CLOCK_SYSTEM_FREQ_MHZ  ((int32_t)80)

这一步修改完之后，保存编译下载程序，在finsh中输入list_device，可以看到以及添加了uart3设备

添加`applications->myuart3.c`，代码如下：

/*
 * Copyright (c) 2006-2021, RT-Thread Development Team
 *
 * SPDX-License-Identifier: Apache-2.0
 *
 * Change Logs:
 * Date           Author       Notes
 * 2022-03-06     F_188       the first version
 */

#include <rtthread.h>

#define UART3_NAME    "uart3" /* 定义串口名称 */
#define RX_DATA_LEN   11      /* 定义接收数据长度 */

static rt_device_t ser;
static struct rt_semaphore rx_sem;
static char rx_data[RX_DATA_LEN];

/* 串口接收中断 */
static rt_err_t  uart3_rx(rt_device_t dev, rt_size_t size)
{
    rt_sem_release(&rx_sem);
    return RT_EOK;
}

/* 串口线程入口 */
static void ser3_tid_entry(void *p)
{
    rt_uint8_t i = 0, j;
    char ch;
    rt_uint8_t START_RX_FLAG = 0;

    while(1)
    {
        while(rt_device_read(ser, -1, &ch, 1) != 1) /* 每接收一个字符则循环一次 */
        {
            rt_sem_take(&rx_sem, RT_WAITING_FOREVER); /* 等待获取信号量 */

            if(i < RX_DATA_LEN)
            {
                if(ch == '$' || START_RX_FLAG)        /* 自定义数据头为"$" */
                {
                    START_RX_FLAG = 1;
                    rx_data[i++] = ch;
                }

                if(i == RX_DATA_LEN - 1)              /* 打印输出 */
                {
                    i = 0;
                    START_RX_FLAG = 0;
                    for(j = 0; j < RX_DATA_LEN; j++)
                    {
                        rt_kprintf("%c", rx_data[j]);
                    }
                    rt_kprintf("\n");
                }
            }
        }
    }
}

static int uart3_init(void)
{
    rt_err_t ret = RT_EOK;

    // 初始化串口3
    ser = rt_device_find(UART3_NAME);   /* 寻找设备 */
    if(!ser)
    {
        rt_kprintf("find %s failed\n", UART3_NAME);
        return -RT_ERROR;
    }

    ret = rt_device_open(ser, RT_DEVICE_FLAG_INT_RX); /* 打开设备 */
    if(ret != RT_EOK)
    {
        rt_kprintf("open %s device failed!\n", UART3_NAME);
        return -RT_ERROR;
    }

    rt_device_set_rx_indicate(ser, uart3_rx);  /* 设置串口接收中断 */

    // 初始化线程和信号量
    rt_sem_init(&rx_sem, "rx_sem", 0, RT_IPC_FLAG_FIFO);

    rt_thread_t tid = rt_thread_create("ser3", ser3_tid_entry, RT_NULL, 1024, 25, 10);
    if(tid != RT_NULL)
    {
        rt_thread_startup(tid);
    }
    else
    {
        rt_kprintf("uart3 thread init failed!\n");
        ret = -RT_ERROR;
    }

    rt_kprintf("uart3 init success\n");
    return ret;
}
INIT_APP_EXPORT(uart3_init);