J-Link from nRF52840-dk takes several minutes to come up when not connected for a longer time.

Hello,

I have 2 nRF52840-dk developer boards. I'm having a strange and somewhat annoying behavior with the boards. If I haven't connected the boards for a few hours to the usb-port, the boards don't react for a while. The green led on the J-Link (ATSAM3U2CA) does not come on either. After a few minutes it usually works again. The green Led slowly fades in. Sometimes it takes more than 10 minutes, depending a bit on how long they were not connected. If I try to use them during the Led is still not bright lightning SES for example try to reflash the firmware for the chip. As long the Led is not lightning at all SES also doesn't recognize the boards. Bootloader mode is then also not working. If I wait long enough the boards work as normal. Also disconnecting and reconecting with the USB port works directly again.
I already had the device in bootloader mode and reflash the firmware J-Link OB-SAM3U128-V2-NordicSemi 170724 on it. That didn't help. I have the same problem with both my developer boards. I live in Bali and it was difficult to get the boards here. Maybe it's because of the higher humidity, but it's a bit annoying and I'm also concerned that the boards will eventually give up. And since I use the boards to make online projects with students this would not be the best situation. Is this behavior known and is there something I can do about it?

Kind regards
Markus

  • Hi Kenneth,

    I've tried holding a 10KOhm resistor between ground and TP33 and it seems to work. Unfortunately, replacing the resistor R88 with my equipment is not possible without risk due to the small form factor. So probably I will stay with the jumper bridge from VIO_REF to GND or just plug in the board and have a coffee until it's fully loaded.

    Thx a lot for the help.

    Regards
    Markus

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