One of the trickiest support issues to identify is where the driver and system appear to be correctly configured but the touch does not work as expected.
To aid this type of investigation we have incorporated diagnostic and debug functions in the driver and these may indicate that the issue is with the hardware interface, such that the captured debug log may show a USB error has occurred, as per this example mid data read:
2018/06/29-21:37:21: DBG: Read 56 bytes for VID 0x222a PID 0x11e EP 0x82
2018/06/29-21:37:21: DBG: Read 56 bytes for VID 0x222a PID 0x11e EP 0x82
2018/06/29-21:37:21: DBG: Read 56 bytes for VID 0x222a PID 0x11e EP 0x82
2018/06/29-21:37:21: ***: USB: (LIBUSB_TRANSFER_ERROR)
2018/06/29-21:37:21: ***: USB: (LIBUSB_TRANSFER_ERROR closing device)
When investigating USB hardware issues it can sometimes be helpful to have a USB trace to see USB interchange between the driver / system and the device that may help identify why the error is occurring.
In house we have a USB hardware analyser that can be physically connected to the USB port and monitor USB traffic. Being external this is independent of the OS in use.
Where a hardware analyzer is not available (most cases!) it is possible to use a software USB trace tool to capture USB dialog.
Windows does have a very good 3rd party software USB analyzer call usblyzer and this can be quite useful even when trying to identify USB issues in non-Windows systems.
The following is a simple guide how to take a usblyzer trace...
- Download and install usblyzer, preferably 64 bit as all our systems are 64 bit and to view trace logs they need to be created on compatible systems.
- If using an external touch screen that can be plugged into a USB port the run usblyzer and select 'Capture Hot-plugged':
- Now plug in the device or, if using an internal USB device, find and select the device in the device tree.
In this example a touch screen cable from a Dell P2314T monitor has been plugged in and automatically selected:
- Start capture and touch the screen:
- Stop and save capture and email .ulz log file:
