Opensurce Qt6.2 vectorcan can not receive and send CAN-FD message

Shadow_3102

Use vectorcan APIs (Qt 6.2.2 , Qt SerialBus part) to connect Can bus ,but fail to receive can-fd message.
The bus status is always "Unknown" when invoking busStatus() but the hasBusStatus() always return "true", as a result , it make me so confused.

Besides, I try to run can example in Qt6.2 , it show the same warning as above.
So , I wonder whether vectorcan APIs is not good or get some bugs.
I will appreciate it if anyone can give me a hand.

Best Regards

Pablo J. Rogina

@Shadow_3102 said in Opensurce Qt6.2 vectorcan can not receive and send CAN-FD message:

The bus status is always "Unknown"

Is it possible for you to use another non-Qt application/tool to check that your CAN setup is working properly in that machine/PC/device?

Shadow_3102

@Pablo-J-Rogina Thank you for your reply , Pablo. I use TSMaster to connect vectorcan plugin , it works well , which can receive and transmit can-fd mseesage as expected.
So it does make me confused. I am trying to read "XL Driver Library" and run the example provided to find out a solution.

MrShawn

What OS are you using?

If you are on linux and their hardware supports socketcan I would highly recommend using that.

I found this http://martchus.no-ip.biz/doc/qt5/qtserialbus/qtserialbus-vectorcan-overview.html
maybe it can shed some light for you?

Shadow_3102

@MrShawn Thanks for your reply, MrShawn. I use QT6.2 on windows. I have seen the guides before ,but it does not give any help.

And I have found the root cause after several days hard work. Pls see my next comments.

Shadow_3102

After test and reading source code in QT , I have found the root cause .

The answer in in vectorcanbackend.cpp (...\Qt6.2\6.2.2\Src\qtserialbus\src\plugins\canbus\vectorcan),and we can see function named startRead(), source code as follows:

void VectorCanBackendPrivate::startRead()
{
    Q_Q(VectorCanBackend);

    QList<QCanBusFrame> newFrames;

    for (;;) {
        quint32 eventCount = 1;
        if (usesCanFd) {
            XLcanRxEvent event = {};

            const XLstatus status = ::xlCanReceive(portHandle, &event);
            if (Q_UNLIKELY(status != XL_SUCCESS)) {
                if (status != XL_ERR_QUEUE_IS_EMPTY) {
                    q->setError(systemErrorString(status), QCanBusDevice::ReadError);
                }
                break;
            }
            if (event.tag != XL_CAN_EV_TAG_RX_OK)
                continue;

            const XL_CAN_EV_RX_MSG &msg = event.tagData.canRxOkMsg;

            QCanBusFrame frame(msg.id & ~XL_CAN_EXT_MSG_ID,
                QByteArray(reinterpret_cast<const char *>(msg.data), int(msg.dlc)));
            frame.setTimeStamp(QCanBusFrame::TimeStamp::fromMicroSeconds(event.timeStamp / 1000));
            frame.setExtendedFrameFormat(msg.id & XL_CAN_RXMSG_FLAG_EDL);
            frame.setFrameType((msg.flags & XL_CAN_RXMSG_FLAG_RTR)
                                ? QCanBusFrame::RemoteRequestFrame
                                : (msg.flags & XL_CAN_RXMSG_FLAG_EF)
                                    ? QCanBusFrame::ErrorFrame
                                    : QCanBusFrame::DataFrame);

            newFrames.append(std::move(frame));
        } else {
            XLevent event = {};

            const XLstatus status = ::xlReceive(portHandle, &eventCount, &event);
            if (Q_UNLIKELY(status != XL_SUCCESS)) {
                if (status != XL_ERR_QUEUE_IS_EMPTY) {
                    q->setError(systemErrorString(status),
                        QCanBusDevice::ReadError);
                }
                break;
            }
            if (event.tag != XL_RECEIVE_MSG)
                continue;

            const s_xl_can_msg &msg = event.tagData.msg;

            if ((msg.flags & XL_CAN_MSG_FLAG_TX_COMPLETED) && !transmitEcho)
                continue;

            QCanBusFrame frame(msg.id & ~XL_CAN_EXT_MSG_ID,
                QByteArray(reinterpret_cast<const char *>(msg.data), int(msg.dlc)));
            frame.setTimeStamp(QCanBusFrame::TimeStamp::fromMicroSeconds(event.timeStamp / 1000));
            frame.setExtendedFrameFormat(msg.id & XL_CAN_EXT_MSG_ID);
            frame.setLocalEcho(msg.flags & XL_CAN_MSG_FLAG_TX_COMPLETED);
            frame.setFrameType((msg.flags & XL_CAN_MSG_FLAG_REMOTE_FRAME)
                                ? QCanBusFrame::RemoteRequestFrame
                                : (msg.flags & XL_CAN_MSG_FLAG_ERROR_FRAME)
                                   ? QCanBusFrame::ErrorFrame
                                   : QCanBusFrame::DataFrame);

            newFrames.append(std::move(frame));
        }
    }

    q->enqueueReceivedFrames(newFrames);
}

when usesCanFd is true , the data structure "canRxOkMsg" was used to get several fields. However some wrong API was used, for example :

Wrong usages:

QCanBusFrame frame(**msg.id** & ~XL_CAN_EXT_MSG_ID,
        frame.setTimeStamp(QCanBusFrame::TimeStamp::fromMicroSeconds(event.timeStamp / 1000));
        frame.setExtendedFrameFormat(**msg.id** & XL_CAN_RXMSG_FLAG_EDL);
        frame.setFrameType((**msg.flags** & XL_CAN_RXMSG_FLAG_RTR)
                            ? QCanBusFrame::RemoteRequestFrame
                            : (**msg.flags** & XL_CAN_RXMSG_FLAG_EF)
                                ? QCanBusFrame::ErrorFrame
                                : QCanBusFrame::DataFrame);

Correct usages:

QCanBusFrame frame(**msg.canId** & ~XL_CAN_EXT_MSG_ID,
        frame.setTimeStamp(QCanBusFrame::TimeStamp::fromMicroSeconds(event.timeStampSync / 1000));
        frame.setExtendedFrameFormat(**msg.canId** & XL_CAN_RXMSG_FLAG_EDL);
        frame.setFrameType((**msg.msgFlags** & XL_CAN_RXMSG_FLAG_RTR)
                            ? QCanBusFrame::RemoteRequestFrame
                            : (**msg.msgFlags** & XL_CAN_RXMSG_FLAG_EF)
                                ? QCanBusFrame::ErrorFrame
                                : QCanBusFrame::DataFrame);

All latest data structures and APIs are included in vxlapi.h, which is provided by vectorcan and you can get this file by installed "XL Driver Library 20.30.14". The version I use is ”XL Driver Library 20.30.14”.

Snippet code(key point) in vxlapi.h :

// General RX Event
typedef struct {
  unsigned int         size;             // 4 - overall size of the complete event
  unsigned short       tag;              // 2 - type of the event
  unsigned short       channelIndex;     // 2        
  unsigned int         userHandle;       // 4 (lower 12 bit available for CAN)
  unsigned short       flagsChip;        // 2 queue overflow (upper 8bit)
  unsigned short       reserved0;        // 2
  XLuint64             reserved1;        // 8 
  XLuint64             timeStampSync;    // 8 - timestamp which is synchronized by the driver

  union {
    unsigned char             raw[XL_CANFD_MAX_EVENT_SIZE - XL_CANFD_RX_EVENT_HEADER_SIZE];
    XL_CAN_EV_RX_MSG          canRxOkMsg;
    XL_CAN_EV_RX_MSG          canTxOkMsg;
    XL_CAN_EV_TX_REQUEST      canTxRequest;

    XL_CAN_EV_ERROR           canError;
    XL_CAN_EV_CHIP_STATE      canChipState;
    XL_CAN_EV_SYNC_PULSE      canSyncPulse;
  } tagData;
} XLcanRxEvent;


// used with XL_CAN_EV_TAG_RX_OK
typedef struct {
  unsigned int    canId;
  unsigned int    msgFlags;
  unsigned int    crc;
  unsigned char   reserved1[12];
  unsigned short  totalBitCnt;
  unsigned char   dlc;        
  unsigned char   reserved[5];
  unsigned char   data[XL_CAN_MAX_DATA_LEN];
} XL_CAN_EV_RX_MSG;

In addition , the same issues exist in startWrite() .

And I think it is a big bug , needing to fix , so I want to post this issue to Qt but dont know how to do it .
I will appreciate it if you can help me . Or you can contact me directly.

BRs//Hengtai
Email:19047119059@qq.com

aha_1980

Looks like https://forum.qt.io/topic/126887/getting-xl_err_queue_is_empty-when-connecting-to-vector-vn1630a has the same problem

Shadow_3102

I have known the root cause and report the bug to QT Jira:https://bugreports.qt.io/browse/QTBUG-99259

I plan to fix it later but some issus happens in my local develpoment environment . As a result , it may still needs some time to finish it .

Pablo J. Rogina

@Shadow_3102 thank you for sharing your findings and for reporting the issue.

Shadow_3102

This issue has been fixed in 6.4.2.
See details in : https://bugreports.qt.io/browse/QTBUG-99259