Often failed to connect to J-Link of nRF52840 DK

RE: Often failed to connect to J-Link of nRF52840 DK

ovrebekk — Fri, 17 Nov 2023 08:27:24 GMT

Please open a new ticket on this if the problems remain, and provide as much information as you can about what you have tried, which errors you get etc.

Best regards
Torbjørn

RE: Often failed to connect to J-Link of nRF52840 DK

Uvis — Thu, 16 Nov 2023 14:06:33 GMT

I have a similar issue, where the J-link would not connect or I get error message: "connection timed out", sometimes it would work other times it would not.

But this issue is only present when using SES or nrfjprog on Apple Macbook M2 Pro. When using Jlink through command line it always connects with no issues even on the macbook.

It works fine on Windows laptop

RE: Often failed to connect to J-Link of nRF52840 DK

ovrebekk — Mon, 16 Aug 2021 08:06:54 GMT

Thanks for the update.

Usually grounding issues like these are only a problem if you connect some other electrical device (such as an oscilloscope) to the same board. If the laptop and the oscilloscope has a different ground voltage you can get into problems.

Regardless, just let me know if the issue occurs again, and provide some details regarding the situation in which the problem occurs.

Best regards
Torbjørn

RE: Often failed to connect to J-Link of nRF52840 DK

RAlexeev — Thu, 12 Aug 2021 20:53:02 GMT

Thanks for your response!

It's funny that today I didn't have such problem with boards, so there's sense to try another laptop, since I couldn't reproduce it. As soon as I notice the same problem I will try another laptop and without laptop charging that time. My colleague said that probably it's because of MacBook grounding issue, since in Russia MacBook charger adapter has only 2 pin plug (there's not a ground pin). And he recommended to try to ground the MacBook or try another PC with a proper grounding. I will add details and extra tests, when the problem occurs again.

It seems that a similar situation happened here, but for me not the first rebooting has helped: https://devzone.nordicsemi.com/f/nordic-q-a/41538/nrf52840-dk-j-link-not-working

Probably, this is a related case also: https://devzone.nordicsemi.com/f/nordic-q-a/20890/nus-disconnection-happens-when-i-touch-the-pcb. Since right before the describing issue above I noticed the same problem and I was struggling with it. I noticed that a connection between two boards was awful. And it was enough to cover one board by a hand to lose a connection.
And I tried to flash boards with other examples just for experimentation:
https://github.com/zephyrproject-rtos/zephyr/tree/zephyr-v2.6.0/samples/bluetooth/central (without bt_conn_disconnect() function)
https://github.com/zephyrproject-rtos/zephyr/tree/zephyr-v2.6.0/samples/bluetooth/peripheral
And they lost connections too often also. But now it seems everything is okay, although I didn't fix anything intentionally.

RE: Often failed to connect to J-Link of nRF52840 DK

ovrebekk — Thu, 12 Aug 2021 10:58:29 GMT

Thanks for the detailed report.

Have you tried another laptop to see if the issue is related to the laptop itself?

Based on your testing it seems you have tried everything else, trying out different cables, boards etc.

Best regards
Torbjørn