[经验]

一文简析RTT-STUDIO CAN总线通讯

贾桂林

2022-10-18 11:00:44

957 RT-Thread HAL库

1 创建工程，点击 cubemx配置CAN总线

第一步

第二步

点击RT-Thread Settings 选用CAN协议

第一步

第二步使不使能硬件过滤器看自己需求，测试驱动时尽量先不用，正式通讯时在开启

board.h中添加 #define BSP_USING_CAN 和 #define BSP_USING_CAN1 （使用CAN1）
#define BSP_USING_CAN
#define BSP_USING_CAN1

到这里基本就可以用了，但是可能是的BUG，有时候不会自动生成drv_can.c和drv_can.h

RTT的GitHub仓库，下载对应版本的库，我的是4.0.3版本

到对应目录

rt-thread-4.0.3\bsp\stm32\libraries\HAL_Drivers
找到对应文件

参考官方教程

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, 1, 0x700, RT_NULL, RT_NULL), / std,match ID:0x1000x1ff，hdr 为 - 1，设置默认过滤表 /
RT_CAN_FILTER_ITEM_INIT(0x300, 0, 0, 1, 0x700, RT_NULL, RT_NULL), / std,match ID:0x3000x3ff，hdr 为 - 1 /
RT_CAN_FILTER_ITEM_INIT(0x211, 0, 0, 1, 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, 1, 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);