RT-Thread-RT-Thread Studio 上的CAN实践RT-Thread问答社区

RT-Thread Studio 上的CAN实践

发布于 2023-06-15 14:35:30 浏览：1997 订阅该版

1.前言说明
  CAN 是Controller Area Network 的缩写（以下称为CAN），是ISO*1 国际标准化的串行通信协议。
在当前的汽车产业中，出于对安全性、舒适性、方便性、低公害、低成本的要求，各种各样的电子控制系统
被开发了出来。由于这些系统之间通信所用的数据类型及对可靠性的要求不尽相同，由多条总线构成的情况很
多，线束的数量也随之增加。为适应“减少线束的数量”、“通过多个LAN，进行大量数据的高速通信”的需
要，1986 年德国电气商博世公司开发出面向汽车的CAN 通信协议。此后，CAN 通过ISO11898 及ISO11519 进行了标准化，现在在欧洲已是汽车网络的标准协议。现在，CAN 的高性能和可靠性已被认同，并被广泛地应用于工业自动化、船舶、医疗设备、工业设备等方面。
瑞萨在RA6M3系列芯片 集成CAN总线控制器。Controller Area Network (CAN) Module 详细参考《Renesas RA6M3 Group User’s Manual: Hardware》

1.1.本章内容
   使用RT-Thread Studio来创建工程，配置CAN接口驱动，编写CAN接口测试程序，实现瑞萨RA6M3芯片和上    位机CAN通信（数据接收与发送）。

1.2.模块介绍
   CAN接口图

![screenshot_image.png](https://oss-club.rt-thread.org/uploads/20230615/13be1b4d8d98bbef0b06a83608d6a35b.png)

![screenshot_image.png](https://oss-club.rt-thread.org/uploads/20230615/9c842909851dc88476596dfb45cba7cc.png.webp)

![screenshot_image.png](https://oss-club.rt-thread.org/uploads/20230615/2902f6497edbef3b132e95a36f660418.png.webp)

1.3.开发软件
    RT-Thread Studio   ， RA Smart Configurator
2.步骤说明
2.1.新建工程
    
![screenshot_image.png](https://oss-club.rt-thread.org/uploads/20230615/366228ea54e239113a3713d7870ce1a5.png.webp)

![screenshot_image.png](https://oss-club.rt-thread.org/uploads/20230615/5da8c34a0746ff8894e7fd0d5240ea20.png.webp)

![screenshot_image.png](https://oss-club.rt-thread.org/uploads/20230615/3ce5a5c3288a1b52fc15f16966d7ca15.png.webp)

2.2.编写测试程序
https://gitee.com/zkarm2008/can2023.git

```c
/*
 * Copyright (c) 2006-2021, RT-Thread Development Team
 *
 * SPDX-License-Identifier: Apache-2.0
 *
 * Change Logs:
 * Date           Author       Notes
 * 2023-06-15     Administrator       the first version
 */

#include <rtthread.h>
#include "hal_data.h"
#include <rtdevice.h>

#define CAN_DEV_NAME       "can0"      /* CAN 设备名称 */

static struct rt_semaphore rx_sem;     /* 用于接收消息的信号量 */

static rt_device_t can_dev;            /* CAN 设备句柄 */
static int can_echo( rt_uint8_t *p_buff );

/* 接收数据回调函数 */
static rt_err_t can_rx_call(rt_device_t dev, rt_size_t size)
{
    /* CAN 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 can_rx_thread(void *parameter)
{
    int i;
    rt_err_t res;
    struct rt_can_msg rxmsg = {0};

/* 设置接收回调函数 */
    rt_device_set_rx_indicate(can_dev, can_rx_call);

#ifdef RT_CAN_USING_HDR
    struct rt_can_filter_item items[5] =
    {
        RT_CAN_FILTER_ITEM_INIT(0x100, 0, 0, 0, 0x700, RT_NULL, RT_NULL), /* std,match ID:0x100~0x1ff，hdr 为 - 1，设置默认过滤表 */
        RT_CAN_FILTER_ITEM_INIT(0x300, 0, 0, 0, 0x700, RT_NULL, RT_NULL), /* std,match ID:0x300~0x3ff，hdr 为 - 1 */
        RT_CAN_FILTER_ITEM_INIT(0x211, 0, 0, 0, 0x7ff, RT_NULL, RT_NULL), /* std,match ID:0x211，hdr 为 - 1 */
        RT_CAN_FILTER_STD_INIT(0x486, RT_NULL, RT_NULL),                  /* std,match ID:0x486，hdr 为 - 1 */
        {0x555, 0, 0, 0, 0x7ff, 7,}                                       /* std,match ID:0x555，hdr 为 7，指定设置 7 号过滤表 */
    };
    struct rt_can_filter_config cfg = {5, 1, items}; /* 一共有 5 个过滤表 */
    /* 设置硬件过滤表 */
    res = rt_device_control(can_dev, RT_CAN_CMD_SET_FILTER, &cfg);
    RT_ASSERT(res == RT_EOK);
#endif

while (1)
    {
        /* hdr 值为 - 1，表示直接从 uselist 链表读取数据 */
        //rxmsg.hdr_index = -1;
        /* 阻塞等待接收信号量 */
        rt_sem_take(&rx_sem, RT_WAITING_FOREVER);
        /* 从 CAN 读取一帧数据 */
        rt_device_read(can_dev, 0, &rxmsg, sizeof(rxmsg));
        /* 打印数据 ID 及内容 */
        rt_kprintf("ID:%x", rxmsg.id);
        for (i = 0; i < 8; i++)
        {
            rt_kprintf("%2x", rxmsg.data[i]);
        }
        can_echo( &rxmsg.data[0]);
        rt_kprintf("\n");
    }
}

static int can_echo( rt_uint8_t *p_buff )
{
           struct rt_can_msg msg = {0};
           rt_size_t  size;

msg.id  = 0x03;              /* ID 为 0x03 */
            msg.ide = RT_CAN_STDID;     /* 标准格式 */
            msg.rtr = RT_CAN_DTR;       /* 数据帧 */
            msg.len = 8;                /* 数据长度为 8 */
            rt_memcpy(&msg.data[0], p_buff, 8);
            /* 发送一帧 CAN 数据 */
            size = rt_device_write(can_dev, 0, &msg, sizeof(msg) );
            if (size == 0)
            {
                rt_kprintf("can dev write data failed!\n");
            }

}

int can_test(int argc, char *argv[])
{
    struct rt_can_msg msg = {0};
    rt_err_t res;
    rt_size_t  size;
    rt_thread_t thread;
    char can_name[RT_NAME_MAX];

if (argc == 2)
    {
        rt_strncpy(can_name, argv[1], RT_NAME_MAX);
    }
    else
    {
        rt_strncpy(can_name, CAN_DEV_NAME, RT_NAME_MAX);
    }
    /* 查找 CAN 设备 */
    can_dev = rt_device_find(can_name);
    if (!can_dev)
    {
        rt_kprintf("find %s failed!\n", can_name);
        return RT_ERROR;
    }

/* 初始化 CAN 接收信号量 */
    rt_sem_init(&rx_sem, "rx_sem", 0, RT_IPC_FLAG_FIFO);

/* 以中断接收及发送方式打开 CAN 设备 */
    res = rt_device_open(can_dev, RT_DEVICE_FLAG_INT_TX | RT_DEVICE_FLAG_INT_RX);
    RT_ASSERT(res == RT_EOK);

/* 设置 CAN 的工作模式为正常工作模式 */
    //res = rt_device_control(can_dev, RT_CAN_CMD_SET_MODE, (void *)RT_CAN_MODE_NORMAL);
    /* 设置 CAN 通信的波特率为 100kbit/s*/
    //res = rt_device_control(can_dev, RT_CAN_CMD_SET_BAUD, (void *)CAN100kBaud);

/* 创建数据接收线程 */
    thread = rt_thread_create("can_rx", can_rx_thread, RT_NULL, 1024, 25, 10);
    if (thread != RT_NULL)
    {
        rt_thread_startup(thread);
    }
    else
    {
        rt_kprintf("create can_rx thread failed!\n");
    }

return res;
}

/* 导出到 msh 命令列表中 */

MSH_CMD_EXPORT(can_test, can device sample);
```

![screenshot_image.png](https://oss-club.rt-thread.org/uploads/20230615/e62e6d4b0a7368d6553c434b4e58f2bc.png.webp)

3.代码验证
 编译程序并下载到开发板

![screenshot_image.png](https://oss-club.rt-thread.org/uploads/20230615/8ece3e2a4489a8982f96d07bd23fd7f6.png.webp)

![screenshot_image.png](https://oss-club.rt-thread.org/uploads/20230615/8e67ee64fe2c91efe6f6e2c949b25c1d.png.webp)

使用CANFD（USB转CAN ）发送和接收开发板CAN通信数据
![screenshot_image.png](https://oss-club.rt-thread.org/uploads/20230615/5a66eae124914616eda1cf8b1af6c7ad.png.webp)
4.章节总结
  本章主要是验证了开发板和上位机CAN通信，RT-THREAD 开发板BSP 适配的很好，各种软件组件比较丰富，可以节省很多开发时间。