CAN BUS 帧不通过代码发送答案

【问题标题】：CANBUS frames not send throught codeCAN BUS 帧不通过代码发送
【发布时间】：2018-05-15 06:37:26
【问题描述】：

我有一个 Raspberry Pi，它通过 SPI 连接 CAN 总线。我已经安装了canutils，如果我执行 cansend，则消息会被控制器接收并应用，但如果我通过代码执行此操作，则不会。这一定是我在构建框架时做错了什么，所以如果有人能帮助我指出我的错误，我会很感激。

这是我发送的 cansend 消息。

cansend can0 01f801f2#1212121223232323

这是我发送相同消息的代码。代码在 pthread 中运行。

void *CANUpdate(void *userParam)
{
    struct sockaddr_can addr;
    struct ifreq ifr;
    const char *ifname = "can0";
    int can_s;

    if ((can_s = socket(PF_CAN, SOCK_RAW, CAN_RAW)) < 0)
    {
        LogEntry(LOG_ERR, "Error while opening socket\n");
        return 0;
    }

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

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

    if (bind(can_s, (struct sockaddr *)&addr, sizeof(addr)) < 0)
    {
        LogEntry(LOG_ERR, "Error in CAN socket bind\n");
        return 0;
    }

    while (!stopServer)
    {
        if (can_s)
        {
            struct can_frame frame;
            frame.can_id = 0x01f801f2;
            frame.can_dlc = 8;
            frame.data[0] = 0x12;
            frame.data[1] = 0x12;
            frame.data[2] = 0x12;
            frame.data[3] = 0x12;
            frame.data[4] = 0x34;
            frame.data[5] = 0x34;
            frame.data[6] = 0x34;
            frame.data[7] = 0x34;

            int res = write(can_s, &frame, sizeof(struct can_frame));
        }
        msleep(800);
    }
}

【问题讨论】：

标签： c++ raspberry-pi3 can-bus debian-stretch

【解决方案1】：

代码基本上有两个问题。 1. 我应该使用 canfd_frame 结构，并且应该将值设为 0。这是最后工作的代码

void *CANUpdate(void *userParam)
{
    struct sockaddr_can addr;
    struct ifreq ifr;
    const char *ifname = "can0";
    int can_s;

    if ((can_s = socket(PF_CAN, SOCK_RAW, CAN_RAW)) < 0)
    {
        LogEntry(LOG_ERR, "Error while opening socket\n");
        return 0;
    }

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

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

    setsockopt(can_s, SOL_CAN_RAW, CAN_RAW_FILTER, NULL, 0);

    if (bind(can_s, (struct sockaddr *)&addr, sizeof(addr)) < 0)
    {
        LogEntry(LOG_ERR, "Error in CAN socket bind\n");
        return 0;
    }

    while (!stopServer)
    {
        if (can_s)
        {
        struct canfd_frame frame;
        memset(&frame, 0, sizeof(frame)); /* init CAN FD frame, e.g. LEN = 0 */
        frame.can_id = 0x01f801f2;
        frame.len = 8;

        if (!(frame.can_id & CAN_ERR_FLAG)) /* 8 digits but no errorframe?  */
            frame.can_id |= CAN_EFF_FLAG;   /* then it is an extended frame */

            frame.data[0] = 0x12;
            frame.data[1] = 0x12;
            frame.data[2] = 0x12;
            frame.data[3] = 0x12;
            frame.data[4] = 0x34;
            frame.data[5] = 0x34;
            frame.data[6] = 0x34;
            frame.data[7] = 0x34;

            if(write(can_s, &frame, sizeof(struct can_frame)) != sizeof(struct can_frame);
            LogEntry(LOG_ERR, "Unable to write CAN message\n");
        }
        msleep(800);
    }
}

【讨论】：