嵌入式Linux如何用C读写can

嵌入式Linux可以通过SocketCAN接口来读写CAN总线。以下是使用C语言编写的读写CAN的示例代码：

读CAN数据：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <net/if.h>
#include <linux/can.h>
#include <linux/can/raw.h>

int main(void)
{
    int s;
    struct sockaddr_can addr;
    struct ifreq ifr;
    struct can_frame frame;
    int nbytes;

    const char *ifname = "can0";

    /* create socket */
    if ((s = socket(PF_CAN, SOCK_RAW, CAN_RAW)) < 0) {
        perror("socket");
        return 1;
    }

    /* set up can interface */
    strcpy(ifr.ifr_name, ifname);
    ioctl(s, SIOCGIFINDEX, &ifr);
    addr.can_family = AF_CAN;
    addr.can_ifindex = ifr.ifr_ifindex;
    if (bind(s, (struct sockaddr *)&addr, sizeof(addr)) < 0) {
        perror("bind");
        return 1;
    }

    /* read data */
    while(1) {
        nbytes = read(s, &frame, sizeof(struct can_frame));
        if (nbytes < 0) {
            perror("read");
            return 1;
        }
        printf("ID=%X DLC=%d data=", frame.can_id, frame.can_dlc);
        for (int i = 0; i < frame.can_dlc; i++) {
            printf("%02X ", frame.data[i]);
        }
        printf("\n");
    }

    return 0;
}

写CAN数据：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <net/if.h>
#include <linux/can.h>
#include <linux/can/raw.h>

int main(void)
{
    int s;
    struct sockaddr_can addr;
    struct ifreq ifr;
    struct can_frame frame;
    int nbytes;

    const char *ifname = "can0";

    /* create socket */
    if ((s = socket(PF_CAN, SOCK_RAW, CAN_RAW)) < 0) {
        perror("socket");
        return 1;
    }

    /* set up can interface */
    strcpy(ifr.ifr_name, ifname);
    ioctl(s, SIOCGIFINDEX, &ifr);
    addr.can_family = AF_CAN;
    addr.can_ifindex = ifr.ifr_ifindex;
    if (bind(s, (struct sockaddr *)&addr, sizeof(addr)) < 0) {
        perror("bind");
        return 1;
    }

    /* write data */
    frame.can_id = 0x123;
    frame.can_dlc = 8;
    frame.data[0] = 0x01;
    frame.data[1] = 0x02;
    frame.data[2] = 0x03;
    frame.data[3] = 0x04;
    frame.data[4] = 0x05;
    frame.data[5] = 0x06;
    frame.data[6] = 0x07;
    frame.data[7] = 0x08;

    nbytes = write(s, &frame, sizeof(struct can_frame));
    if (nbytes < 0) {
        perror("write");
        return 1;
    }

    return 0;
}

需要注意的是，读写CAN总线需要使用root权限，或者将用户添加到can组中。同时，需要在系统中安装SocketCAN支持，具体安装方法可以参考Linux内核文档中的相关章节。