Missing characters when 2D datamatrix barcode is scanned

SMario

Hi All,

I am facing an issue with scanned 2D datamatrix barcode where I see different characters missing on scans. This issue is happening only on Linux. GD4500 Datamatrix Scanner works as keyboard wedge here and I use event filter installed on qApp (QGuiApplicaiton) to read the scanned data. I see that data is missing when I put qDebug inside event filter.

bool USBPortReader::eventFilter(QObject *obj, QEvent *event)
{
    Q_UNUSED(obj);

    if (event->type() == QEvent::KeyPress)
    {
        QKeyEvent *keyEvent = static_cast<QKeyEvent *>(event);

        qDebug() << "Recieved data : " << keyEvent->text();

I tested, using evtest applicaiton to see if we recieve all data from the driver and it prints all data in barcode everytime I scan.

I tried changed the USB Keyboard speed of the barcode scanner from 1 ms to 10 ms and it improves the scans (fewer characters are missing afterwards). Cannot increase more than 10 ms as it is the max supported by scanner.

I wanted to try setting keyboardInputInterval property but it is only available for QApplication and not for QGuiApplication. Can someone help me on how I can adjust the setting on QGuiApplicaiton ? I cannot set this directly on X11 as our embedded applicaiton uses eglfs/framebuffer.

Any leads or support is highly appreciated. Thank you in advance.

robert1997b

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