Flashing and debugging an external nrf52840 board with the nRF52840 DK different to those covered in forum

[David Guest]

I have read the other threads regarding this, but doesn't appear to work.

I have noticed on my nRF52840 DK that P20 has a different pinout 

So I have tried an assortment of connections to this board to the SWDIO,SWDCLK,SWO and VDD.

I am unsure whether the idea is to ground my board to the dev board seperately and wire the GND of my connector to the SELECT pin.

No matter what I do the Programmer tools always sees the onboard device.  

I close and reopen the programmer each time, as I don't know if it auto-updates dynamically.

[Simonr]

Hi

Yes, P20 on the DKs has had some naming changes (VTG is now called SWD SEL) since the last revision, as we now have an nRF5340 as the debugger MCU. What has changed is that GND is used to detect an external board instead of the voltage like on older revisions. However, the board should be okay to connect as before. See picture below for how the setup should look.

As for the nRF Connect Programmer app, the device to connect to should still be the nRF52840 DK, but it should detect the external board instead of the onboard one if it is connected correctly, and let you program that one.

Best regards,

Simon

[David Guest]

Thanks for reply , so just to confirm, on my dev board (that has 4 more pins than your drawing)

I will connect VIN 3-5V to GND ?

Also does the DK board power our pcb or should I still be powering it from a separate supply ?

[Simonr]

Hi again

No, do not connect VIN 3-5V to GND. In this case is a specific picture of how an nRF52840 DK should be connected to an external board when the external board is powered by the DK.

https://devzone.nordicsemi.com/f/nordic-q-a/51179/debug-out-port-p20-on-nrf52840-dk-debugging-custom-board/204972#204972 

Best regards,

Simon