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  • Case ID: 355663
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Linux USB ports

amelio

I have a nrf9160dk that drives a screen via SPI, using an IT8951 controller. The firmware driving the screen works fine if I plug the USB cable on a power bank or using MS Windows, but the screen updates are not performed when using Linux as host machine, all debug messages are printed correctly via minicom but the screen is doing nothing. Even with a very old Windows version (XP) it works fine but never under Linux. I tried on different computers and different kind of USB ports , v.2 and v.3. I used also the suggested blacklist of udev, to avoid any interference with ModemManager but no success. I was thinking the problem was a lack of power on USB ports so I purchased an external USB hub powered by a separate power supply, but even this solution didn't work. Is there any special configuration on USB that I have to perform under Linux ? Or do you have any indication on how to solve the issue ?

Thanks.

Best Regards

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  • 0

    Maybe it's too obvious:

    Does the nRF9160dk get the data from the PC via USB and then displays that via SPI on that display?

    Maybe it's then just a question of the line-endings/termination. On windows it's common to use  CR+LF, in unix it's only LF. The most terminal programs (both on windows and unix) offers then usually some configuration for that. Try to set that to the windows style (CR+LF) and see, if that works. If it's an application on unix, which feeds the data, try to add a "\r" before "\n".

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  • 0

    Maybe it's too obvious:

    Does the nRF9160dk get the data from the PC via USB and then displays that via SPI on that display?

    Maybe it's then just a question of the line-endings/termination. On windows it's common to use  CR+LF, in unix it's only LF. The most terminal programs (both on windows and unix) offers then usually some configuration for that. Try to set that to the windows style (CR+LF) and see, if that works. If it's an application on unix, which feeds the data, try to add a "\r" before "\n".

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  • 0 in reply to Achim Kraus

    Thanks, but this is not the case. The data are received via LTE-M internal modem and then displayed via SPI. The USB is only used to power the board and see the debug messages on /dev/ttyACM0. I suspect that there is a difference (between Windows and Linux) in managing the power of USB port or some kind of interference between the power and the virtual ttys. With Windows or a generic USB power supply the app works fine, while under Linux (I used different flavors and releases) it works fine for all parts of the app except when it writes to screen via SPI.

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