nRF54L15-DK - how to connect to external MCU?

RE: nRF54L15-DK - how to connect to external MCU?

PjGlasso — Wed, 19 Nov 2025 05:19:56 GMT

HI there,

So Short answer "YES"

The TLDR version has a Thread on Seeed Studio Support forum https://forum.seeedstudio.com/t/use-rtt-no-console-required-logging-debugging-and-diagnostics/294544/1 where I use the nRF54L15_DK and P19 connected via the SWD to a nRF54L15 Xiao Sense (IMU) sitting on the Xiao Dev_board with the SWD connected.

I use the RTT viewer and the JLink Commander to connect, Halt, test and set registers of the Xiao and then HIT GO! and I can watch the RTT viewer output of Serial data from the Xiao (power-ON message & debug printF basically.

You got to love this Nordic Platform the stuff just works. ✌

HTH

GL 😁 PJ ✌

RE: nRF54L15-DK - how to connect to external MCU?

Alex P — Tue, 18 Nov 2025 09:40:02 GMT

Hi Simon,

I was able to connect and program external board via P19.

However, when I try to open up J-Link RTT Viewer it is not showing any output on the debug console in SWD connection mode (but when the same firmware runs on DK board it shows output in the same SWD connection mode).

Is it an expected behaviour and is there any way to obtain RTT console output from the external board?

Thanks

WBR,

Alex

RE: nRF54L15-DK - how to connect to external MCU?

Simonr — Fri, 10 Oct 2025 12:46:54 GMT

Like PJ says, P19 is the connector to use. Here is the page in the nRF54L15 DK user guide describing how to program external boards. https://docs.nordicsemi.com/bundle/ug_nrf54l15_dk/page/UG/nRF54L15_DK/program_debug/debug_out_ext_board.html

Best regards,

Simon

RE: nRF54L15-DK - how to connect to external MCU?

PjGlasso — Fri, 10 Oct 2025 02:39:27 GMT

Hi there,

I'm doing same as a few others here, using the external Jlink capabilities to program/debug via SWD.

P19 is the connector, Here isa video I did on the subject and the adapter I used as well as some Key caveats to getting it going.

For you start with the board config first, Get it set for the VDD you use.

Once connected properly you can use JLink commands and the Programmer app in Nrf_connect for Desktops.

https://forum.seeedstudio.com/t/xiao-nrf54l15-an-error-occurred-memory-transfer-fault-0x00ffc31c-0x00ffc31f/293792/53?u=pj_glasso

or video is here Directly

https://vimeo.com/1125305838?fl=pl&fe=sh

vimeo.com/1125305838

HTH

GL :-) PJ :v: