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RT-Thrad-CAN通信

发布于 2022-05-30 17:44:10 浏览：1474 订阅该版

[tocm]

# 1. 简述
开发硬件：正点原子STM32F407
开发软件：RT-Thread Studio
RTT版本：4.0.3
[RTT参考文档](https://www.rt-thread.org/document/site/#/rt-thread-version/rt-thread-standard/programming-manual/device/can/can)

# 2. STM32CubeMx配置

基于芯片创建工程，使用STM32CubeMx配置时钟和CAN外设。

![1](https://img-blog.csdnimg.cn/1d314eeb81bc4a0386a0d84bb207153f.png)

# 2. 打开CAN驱动框架
![2](https://img-blog.csdnimg.cn/9e09051677b94d6c8f05c6dd4ad03446.png)
# 3. 设置drivers/board.h

```c
#define BSP_USING_CAN
#define BSP_USING_CAN1
```

# 4. 设置drivers/stm32f4xx_hal_conf_bak.h

```c
#define HAL_CAN_MODULE_ENABLE
```

# 5. 移植drv_can.h和drv_can.c

## 5.1 下载文件

[drv_can.h和drv_can.c下载链接](https://github.com/RT-Thread/rt-thread/tree/v4.0.3/bsp/stm32/libraries/HAL_Drivers)
将drv_can.h放到drivers/include目录，将drv_can.c放到drivers目录。

## 5.2 修改文件

我设置STM32F407的APB1时钟频率为42MHz，需要在drv_can.c修改配置。
波特率 = APB1/(1+CAN_BS1_TQ+CAN_BS2_TQ)/分频系数。
这里我只修改了1M和500K的通信速率。

```c
#elif defined (SOC_SERIES_STM32F4)/* APB1 45MHz(max) */
static const struct stm32_baud_rate_tab can_baud_rate_tab[] =
{
//    {CAN1MBaud, (CAN_SJW_2TQ | CAN_BS1_9TQ  | CAN_BS2_5TQ | 3)},
//    {CAN800kBaud, (CAN_SJW_2TQ | CAN_BS1_8TQ  | CAN_BS2_5TQ | 4)},
//    {CAN500kBaud, (CAN_SJW_2TQ | CAN_BS1_9TQ  | CAN_BS2_5TQ | 6)},
//    {CAN250kBaud, (CAN_SJW_2TQ | CAN_BS1_9TQ  | CAN_BS2_5TQ | 12)},
//    {CAN125kBaud, (CAN_SJW_2TQ | CAN_BS1_9TQ  | CAN_BS2_5TQ | 24)},
//    {CAN100kBaud, (CAN_SJW_2TQ | CAN_BS1_9TQ  | CAN_BS2_5TQ | 30)},
//    {CAN50kBaud, (CAN_SJW_2TQ | CAN_BS1_9TQ  | CAN_BS2_5TQ | 60)},
//    {CAN20kBaud, (CAN_SJW_2TQ | CAN_BS1_9TQ  | CAN_BS2_5TQ | 150)},
//    {CAN10kBaud, (CAN_SJW_2TQ | CAN_BS1_9TQ  | CAN_BS2_5TQ | 300)}
    /* APB1 42MHz APB1/(1+CAN_BS1_15TQ+CAN_BS2_5TQ)/最后一位 */
    {CAN1MBaud, (CAN_SJW_2TQ | CAN_BS1_15TQ  | CAN_BS2_5TQ | 2)},   //通过
    {CAN800kBaud, (CAN_SJW_2TQ | CAN_BS1_8TQ  | CAN_BS2_5TQ | 4)},
    {CAN500kBaud, (CAN_SJW_2TQ | CAN_BS1_15TQ  | CAN_BS2_5TQ | 4)}, //通过
    {CAN250kBaud, (CAN_SJW_2TQ | CAN_BS1_15TQ  | CAN_BS2_5TQ | 8)},
    {CAN125kBaud, (CAN_SJW_2TQ | CAN_BS1_9TQ  | CAN_BS2_5TQ | 24)},
    {CAN100kBaud, (CAN_SJW_2TQ | CAN_BS1_9TQ  | CAN_BS2_5TQ | 30)},
    {CAN50kBaud, (CAN_SJW_2TQ | CAN_BS1_9TQ  | CAN_BS2_5TQ | 60)},
    {CAN20kBaud, (CAN_SJW_2TQ | CAN_BS1_9TQ  | CAN_BS2_5TQ | 150)},
    {CAN10kBaud, (CAN_SJW_2TQ | CAN_BS1_9TQ  | CAN_BS2_5TQ | 300)}
};
```

# 6. 测试代码

测试代码如下，默认通信速率为1M。

```c
/*
 * 程序清单：这是一个 CAN 设备使用例程
 * 例程导出了 can_sample 命令到控制终端
 * 命令调用格式：can_sample can1
 * 命令解释：命令第二个参数是要使用的 CAN 设备名称，为空则使用默认的 CAN 设备
 * 程序功能：通过 CAN 设备发送一帧，并创建一个线程接收数据然后打印输出。
*/

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

#define CAN_DEV_NAME       "can1"      /* 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 */

/* 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 = -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]);
        }

rt_kprintf("\n");
    }
}

int can_sample(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);
    /* 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");
    }

msg.id = 0x78;              /* ID 为 0x78 */
    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 */
    /* 待发送的 8 字节数据 */
    msg.data[0] = 0x00;
    msg.data[1] = 0x11;
    msg.data[2] = 0x22;
    msg.data[3] = 0x33;
    msg.data[4] = 0x44;
    msg.data[5] = 0x55;
    msg.data[6] = 0x66;
    msg.data[7] = 0x77;
    /* 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");
    }

return res;
}
/* 导出到 msh 命令列表中 */
MSH_CMD_EXPORT(can_sample, can device sample);
```

# 7. 设置通信速率

```c
/* drivers/drv_can.c */
int rt_hw_can_init(void)
{
	struct can_configure config = CANDEFAULTCONFIG;
	......
	drv_can1.device.config = config;
}
```

```c
/* components/drivers/include/drivers/can.h */
#define CANDEFAULTCONFIG \
{                        \
	CAN1MBaud,            \
	RT_CANMSG_BOX_SZ,     \
	RT_CANSND_BOX_NUM,    \
	RT_CAN_MODE_NORMAL,   \
};
```

分析完源码后，发现CAN的通信速录由CANDEFAULTCONFIG 设定，最简单的修改如下。

```c
#define CANDEFAULTCONFIG \
{                        \
	CAN500kBaud,          \ //修改速率为500K
	RT_CANMSG_BOX_SZ,     \
	RT_CANSND_BOX_NUM,    \
	RT_CAN_MODE_NORMAL,   \
};
```