[ABANDONED] SWOViewer output from nrf52840 was working with J-Link EDU mini, but now it's blank...

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  • [ABANDONED] SWOViewer output from nrf52840 was working with J-Link EDU mini, but now it's blank...

    I have a number of individuals using the same hardware setup and a common VM configuration with the SEGGER toolchain installed. Our debugging setup uses the J-Link GDB server, which is initiated using the command JLinkGDBServer -device nRF52840_xxAA -endian little -if SWD -speed 4000 and a SWO output in a separate window that is initiated using the command JLinkSWOViewer_CL -device nRF52840_xxAA -cpufreq 64000000 -swofreq 4000000.

    For the first few weeks, this was working for everyone. Starting recently, a team of two reported that their SWO output was blank, despite running code that was previously working. Both individuals are using the same common Ubuntu 20.04 VM setup, running in VMWare Fusion on a Mac laptop. We have tried completely re-flashing the target board to stock firmware, we've tried upgrading the J-Link firmware, we've tried downgrading the J-Link firmware, we've tried using all of the SWOViewer variants, we've tried re-installing the original VM image, we've tried re-installing VMWare, and they still get no SWO output.

    Any suggestions? Is the target board faulty? Is the J-Link faulty? I'll consider all suggestions.

    The post was edited 1 time, last by tague ().

  • Hi,
    Thank you for your inquiry.
    Such an issue is not known to us.

    If debugging/flashing in general works, then the J-Link is most likely working properly.


    Could you please send us a J-Link log file of a working and a not working session? How to enable:
    wiki.segger.com/J-Link_DLL#Enable_J-Link_Log_File
    When measuring the SWO line with an Oscilloscope, does it show any activity (Please find the J-Link Interface description here)?
    Does the issue persist on a different PC, OS, J-Link?
    If comparing the working and the not working setup, which are the exact differences?

    Best regards,
    Fabian
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