Unable to connect JLink

RE: Unable to connect JLink

JONATHAN LL — Mon, 05 Jan 2026 11:29:47 GMT

Hi Pedro,

[quote user="PedroMonteiro"] Does it means that the board is not useful anymore with its embedded JLink?[/quote]

you can still use the board to some degree, like using external debugger or if you have a bootloader on the nRF you can use that if you still want to use the DK, but its limited in use as the debugger SoC no longer works as intended.

[quote user="PedroMonteiro"] have another question related to the APPROTECT. I am not able to program the NET Core without a mass erase. Should I open another ticket or continue here?[/quote]

APPROTECT blocks access to both the NET and APP core so you will need to run a recover process to be able to write to them.
You can create a new ticket and discuses best practices for working with the NET core.

Regards,
Jonathan

RE: Unable to connect JLink

PedroMonteiro — Fri, 19 Dec 2025 18:25:24 GMT

Hi Jonathan,

Thanks for your reply. Does it means that the board is not useful anymore with its embedded JLink?

I have another question related to the APPROTECT. I am not able to program the NET Core without a mass erase. Should I open another ticket or continue here?

Regards,
Pedro

RE: Unable to connect JLink

JONATHAN LL — Fri, 19 Dec 2025 14:10:36 GMT

Hi Pedro,

The new DK's have a different debugger chip on them so they behave a bit differently. We have seen some cases where customers end up damaging the USB line and the communication with the DK stops working though the debugger IC. the rest of the DK still works as normal, but its no longer as simple to program\debug on as you would need an external debugger.

But looks like the debugger IC works here as it is able to report kit and device id. Often this is then related to some HW modifications to the board, maybe a jumper or a solder bridge is modified?

But good to see that there is some progress here, seems most of the setup works as expected and that the issue lies with the DK.

Regards,
Jonathan

RE: Unable to connect JLink

PedroMonteiro — Wed, 17 Dec 2025 20:58:59 GMT

Hi,

Just received another DK and this one is running okay. I'm afraid the board is damaged. It started to fail USB enumeration but after several usb driver updates the led blinks for a while and gets steady. But

C:\Program Files\SEGGER>nrfutil device list
1050094672
Product J-Link
Board version PCA10095
Traits devkit, usb

Supported devices found: 1

C:\Program Files\SEGGER>nrfutil device recover
Error: Missing --traits or --serial-number options. Add at least one of the options or make sure you have exactly one supported device connected

I tried different USB cables and I'm running Windows 11 Pro version 25H2 x64

I had similar problems in the past but I was able to recover by re-installing USB drivers. Not anymore.

Regards,

Pedro

RE: Unable to connect JLink

JONATHAN LL — Mon, 15 Dec 2025 12:00:32 GMT

Hi,

Can you share some info of the system? OS verison, JLink verison?

How many units have you tested? is it only on DK, have you checked with different USB cables?

Have you tested with nRFUtil or nrfjprog commands?

Regards,
Jonathan