I have a custom board using an nrf52840 chip that I wish to program using the nrf52840-DK board. I have connected the custom board to the DK on P20, using the SWD_CLK, SWD_IO, SWO, and RESET pins (I'm aware RESET isn't needed, but I have it so...). I have also connected VDD and GND from P1 to my board, and GND from P1 to SWD_SEL on P20. This doesn't work though, the programmer always programs the on-board nrf52840.
There appear to be at least 4 different pinouts for P20 that I've seen on different revisions of the nrf52840-DK board so it's not clear how it's supposed to be connected.
My board has the following pins on P20 so if someone could explain which pins are needed, that would be good (please don't just link to diagrams of different boards - I'm specifically referring to this particular pinout):
- VDD nRF
- VDD nRF
- SWD SEL
- SWD IO
- SWD CLK
- SWO
- RESET
- (no label)
- VIN 3-5V
- VDD nRF_HV
- VDD nRF_HV
- VIO REF
- (no label)
(I did see a link to this post, but this is NOT the same pinout I have on my DK - https://devzone.nordicsemi.com/f/nordic-q-a/51179/debug-out-port-p20-on-nrf52840-dk-debugging-custom-board/204972#204972 )
If it's not possible to do this with my board, I have considered removing the nrf52840 from the DK board - would this force the programmer to program the external board? If not, is there some other hardware change/soldering that can be used to disable the on-board nrf52840 so the programmer will only ever program an external board?
