RE: How to use nRF54L15DK to programming the external nRF54L15 customer board

PjGlasso — Mon, 13 Oct 2025 23:05:31 GMT

Hi there,

So The cables must be very short or you WILL get that error. Check out the thread and Video on it. I'm usina a Xiao and SWD connection to P19 (4 wires) SWDCLK, SWDIO, GND, VDD (from my device) If I use anything longer than 3-4 inches Plus 3-4" for jumpers (see Video) Total length not to exceed 6.25"

Video shows what is going on , Full screen.

vimeo.com/1125305838

HTH

GL :-) PJ :v:

RE: How to use nRF54L15DK to programming the external nRF54L15 customer board

Edvin — Mon, 13 Oct 2025 08:07:45 GMT

Try to run this command first:
nrfutil device recover

Does that change anything?

RE: How to use nRF54L15DK to programming the external nRF54L15 customer board

Nasib — Fri, 10 Oct 2025 17:09:30 GMT

Same isue here and i can not program external boards:

SWDO_VTG to external board VDD
SWDO_SWDIO to external board SWDIO
SWDO_SELECT shorted to GND
SWDO_SWDCLK to external board SWDCLK
GND to external board GND

I power the external board ( so the VTG pin will be 3V now )

I always get this unles i disconnect SEL from GND

19:08:58.927

Failed "reading readback protection status for application core". Error: code: 1, description: Generic, message: Batch task protection-get failed, Device error: Setting the debug port SELECT register failed while powering up sys and debug regions (Unknown Error in J-Link DLL (error code =-1)). This might indicate that the debug port is unavailable. Please double-check device power supply and SWD lines, and that SWD isn't disabled

19:08:58.946

Error: Failed with exit code 1. One or more batch tasks failed: * 1057785450: Device error: Setting the debug port SELECT register failed while powering up sys and debug regions (Unknown Error in J-Link DLL (error code =-1)). This might indicate that the debug port is unavailable. Please double-check device power supply and SWD lines, and that SWD isn't disabled (Generic) Message: Batch task protection-get failed, Device error: Setting the debug port SELECT register failed while powering up sys and debug regions (Unknown Error in J-Link DLL (error code =-1)). This might indicate that the debug port is unavailable. Please double-check device power supply and SWD lines, and that SWD isn't disabled.

19:08:58.946

RE: How to use nRF54L15DK to programming the external nRF54L15 customer board

Edvin — Tue, 11 Mar 2025 21:21:28 GMT

Those seems to be the ones you need, roughly. But you also need to connect GND to GND, and you need to power the external board. You can power it from the DK if you like, but SWD0_VTG doesn't power the external board.

Best regards,

Edvin