J-Link connection lost after a few seconds

I have been learning to use the nrf52840DK for some time now, though I would consider myself still a beginner. Anyway, something has gone wrong with the kit and I am not sure what. It does not seem to be able to connect with the J-link I've been always using.

Two days ago, I was able to connect it to my PC and download and debug code naturally. I was even able to use the J-Link EDU kit normally, with both the 19-pin and the 9-pin Cortex-M adaptors. Yesterday, I plugged the kit in my PC, as always through the USB. LED5 is on, as always, and the kit is recognized as a J-Link driver. I thought that everything was OK, but in SES, the connect J-Link command returned the "Failed to connect to target" error. The J-Link EDU kit's light was orange. Something has gone terribly wrong. I have tried resetting the kit and downloading the J-Link OB file in the Bootloader, but that does not change anything.

The first time I connected the DK to my PC today, it acted normally and I was even able to connect the J-Link, though LED2 and LED3 were on unexpectedly. I downloaded an example just to see that it works, and at first it worked. After a few seconds the kit was no longer available for J-Link connection in SES (although visible as a J-Link Driver in MyComputer) and the program had stopped its execution (the LEDs were blinking no more). After disconnecting and reconnecting the kit, LED5 is just on, but nothing changed. The downloaded program is not being executed and the J-Link connection is not possible.

Do you know how I could fix this issue?

Thank you in advance!

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  • Hi there,

    If you use nRF Command Line Tools, and run:

    nrfjprog --ids

    Is the kit listed? If not, what error is returned by the program?


    Could run the command again with the log attached?

    nrfjprog --ids --log

    Can you share the log?

    Also, could you go through the steps listed in this thread and verify that none of the suggestions mitigated your issue?

    regards

    Jared

  • Hello! Thank you for your response!

    I run the commands you suggested and the device is listed normally.

    I also followed the steps in the thread you sent (except for the voltage measurement) and nothing worked.

    The first step suggested to check the device manager. In the device manager the device's port is listed as "JLink CDC UART Port" and its drive as "SEGGER MSD Volume USB Device".

    I also tried to recover the kit with the nrfjprog --recover --log command and this was returned.

    Should I try the manual recovery shown here? Are the commands for the nrf52 the same?

    Thank you in advance!

  • Ok, so the computer is able to communicate with the onboard debugger which is good. However, it fails when you try to recover. Can you add the log argument to the recover command:

    nrfjprog --recover --log 

    and share the log?

    Also, can measure the voltage on the RESET pin and the VDD pin on your DK.

    regards

    Jared 

  • Hi again! The "nrfjprog --recover --log" command returns 

    The VDD voltage of the kit is at 2.98V(VDD-GND) and the RESET pin's voltage is 0 (RESET-GND). What baffles me is that the voltage difference between the RESET pin and the VDD pin also appears to be 0.

    Do you have any idea on how to proceed?

  • Hi,

    kostathan said:
    The VDD voltage of the kit is at 2.98V(VDD-GND) and the RESET pin's voltage is 0 (RESET-GND). What baffles me is that the voltage difference between the RESET pin and the VDD pin also appears to be 0.

    This is very strange. RESET should be pulled high, if it's low then the nRF52840 is kept in RESET state. Can you try to pull it high by connecting VDD to RESET and see if it "wakes up" the board.

    regards

    Jared

Reply
  • Hi,

    kostathan said:
    The VDD voltage of the kit is at 2.98V(VDD-GND) and the RESET pin's voltage is 0 (RESET-GND). What baffles me is that the voltage difference between the RESET pin and the VDD pin also appears to be 0.

    This is very strange. RESET should be pulled high, if it's low then the nRF52840 is kept in RESET state. Can you try to pull it high by connecting VDD to RESET and see if it "wakes up" the board.

    regards

    Jared

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