[SOLVED] GDB server won't connect without external target power

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  • [SOLVED] GDB server won't connect without external target power

    Hello,

    I just received a second J-link EDU programmer for a friend. I'm already using mine for two year without problems but when connecting the newly arrived programmer I have a problem.

    My programmer: J-link EDU V8.0
    New programmer: J-link EDU v9.3

    When I connect the new programmer to a development board and try to start the GDB server it won't connect.
    Only when I connect an external power supply to the board the new programmer connects with the IC and the GDB server starts.

    My own programmer doesn't have this issue and I can't find any configuration that could cause this behaviour.

    Both programmers are configure to power the target, and both do because the power LEDs light up when connecting the programmers.

    I've used a develpmentboard with the NXP LPC1766 and one with the NXP LPC1857 both with same results.

    Any suggestions what could cause this difference?

    Many thanks,

    Futience.

  • Hi,

    We are not aware of such an issue.
    Can you please start the J-Link Commander (JLink.exe) while the "new" J-Link is powered and connected to the PC and the target is powered
    through the J-Link (your default setup, which does not work with GDB). Can you please provide a screenshot of the entire J-Link Commander output?


    Best regards
    Erik
    Please read the forum rules before posting.

    Keep in mind, this is *not* a support forum.
    Our engineers will try to answer your questions between their projects if possible but this can be delayed by longer periods of time.
    Should you be entitled to support you can contact us via our support system: segger.com/ticket/
    Or you can contact us via e-mail.

  • Hi Erik,

    Thanks for the reply.
    Do you need me to run a command in the J link commander?

    Attached the screenshot of the J link commander with the new programmer attached and powering the dev board running a LPC1857.
    Although the output shows a 0.00V target voltage the target is powered by the programmer and a programmed LED is flashing.

    Best Regards,

    Futience
    Images

    • Jlink Commander.png

      13.07 kB, 677×343, viewed 952 times

    The post was edited 2 times, last by Futience ().

  • Hi,

    Thanks for providing the screenshot. The problem is that the J-Link does not measure any target voltage. No target voltage == J-Link does not try to connect.
    Did you make sure that J-Link power the target? This can be done by entering the "power on perm" command in J-Link Commander. Afterwards enter the "USB" command
    in order to try to connect to the target again. Does this solve the issue?
    If not, can you please measure the voltage on pin 1 (VTref) of the target interface connector manually?


    Best regards
    Erik
    Please read the forum rules before posting.

    Keep in mind, this is *not* a support forum.
    Our engineers will try to answer your questions between their projects if possible but this can be delayed by longer periods of time.
    Should you be entitled to support you can contact us via our support system: segger.com/ticket/
    Or you can contact us via e-mail.

  • Hi Erik,

    Guess I found the reason for my problem then. I made a adapter to go from the default J-link header to my development board without the Vref connected.
    This suprisingly seems to work with my (older) programmer for years now. I guess I didn't noticed the important functionality of this pin back then.

    With the other development board I tried where the J link programmer can be connected without a custom made cable I forgot to change a jumper setting from external supply to J link supply :wacko:.


    Just tried to connect with the Vref connected and ofcourse all works well! A bit ashamed of my actions I'm happy to be able to use both the programmers from now on.

    The settings of the programmer already are at "Default power on" and I will look at attached solution to prevent the need of connecting the Vref to the development boards.

    Many thanks for the support!


    Best Regards,


    Futience
    Images

    • Control panel.png

      13.04 kB, 566×381, viewed 840 times

    • Supply Adapter.PNG

      265.82 kB, 1,007×832, viewed 900 times

  • Thank you for the feedback.
    Good to hear that you are now up and running.


    Best regards
    Erik
    Please read the forum rules before posting.

    Keep in mind, this is *not* a support forum.
    Our engineers will try to answer your questions between their projects if possible but this can be delayed by longer periods of time.
    Should you be entitled to support you can contact us via our support system: segger.com/ticket/
    Or you can contact us via e-mail.