CAN通信C语言实现收发

CAN总线通信的C语言实现主要包括CAN总线的初始化、发送数据和接收数据三个部分。

首先，需要初始化CAN总线，包括设置波特率、过滤器等参数。下面是一个示例代码：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <linux/can.h>
#include <linux/can/raw.h>

int can_init(char *ifname, int baudrate)  
{
    int s;
    struct ifreq ifr;
    struct sockaddr_can addr;
    struct can_filter rfilter[1];

    s = socket(PF_CAN, SOCK_RAW, CAN_RAW);
    if(s < 0) {
        perror("socket PF_CAN failed");
        return -1;
    }

    strcpy(ifr.ifr_name, ifname);
    ioctl(s, SIOCGIFINDEX, &ifr);

    addr.can_family = PF_CAN;
    addr.can_ifindex = ifr.ifr_ifindex;

    if(bind(s, (struct sockaddr *)&addr, sizeof(addr)) < 0) {
        perror("bind failed");
        return -1;
    }

    rfilter[0].can_id = 0x123;
    rfilter[0].can_mask = CAN_SFF_MASK;
    setsockopt(s, SOL_CAN_RAW, CAN_RAW_FILTER, &rfilter, sizeof(rfilter));

    return s;
}

接下来，可以使用can_send函数向CAN总线发送数据，示例代码如下：

int can_send(int s, unsigned int id, unsigned char *data, unsigned char len)
{
    int nbytes;
    struct can_frame frame;

    frame.can_id = id;
    frame.can_dlc = len;
    memcpy(frame.data, data, len);

    nbytes = write(s, &frame, sizeof(struct can_frame));
    if(nbytes != sizeof(struct can_frame)) {
        perror("write failed");
        return -1;
    }

    return 0;
}

最后，可以使用can_receive函数从CAN总线接收数据，示例代码如下：

int can_receive(int s, unsigned int *id, unsigned char *data, unsigned char *len)
{
    int nbytes;
    struct can_frame frame;

    nbytes = read(s, &frame, sizeof(struct can_frame));
    if(nbytes < sizeof(struct can_frame)) {
        perror("read failed");
        return -1;
    }

    *id = frame.can_id;
    *len = frame.can_dlc;
    memcpy(data, frame.data, *len);

    return nbytes;
}

需要注意的是，以上代码仅供参考，实际使用时需要根据具体的应用场景进行修改和优化。同时，对于一个完整的CAN总线应用程序，还需要考虑各种异常情况的处理，如错误码的处理、超时的处理等。