I have a nRF52-DK and I am trying to programme an external designed by myself but this one contains the nRF51422 chip. I am using nRFGO Studio to upload the .HEX file.
Do you know if it is possible even with different chips?
I am following these connections between my board and nRF52-DK.
My Board(nRF51422) -> nRF52-DK
SWDIO -> SH_SWDIO (pin #4) on P20
SWDCLK -> SH_SWDCLK (pin #5) on P20
VDD -> SH_VTG (pin #3) on P20 and VDD (pin #1)
GND -> SH_GND_DETECT (pin #8) on P20 and GND
It is possible. I am using P19 on nRF52-DK, and i just connect 4 lines from it: VCC(pin1), SWDIO(pin2), GND(pin3), SWDCLK(pin4 and wire them to corresponding pins on nRF51 chip. I am programming/debugging without problems that way.
External (nRF51) chip has to be powered to be detected by programmer that way (if not, nRF52-DK onboard nrf52832 will be detected only).
More info here
This question is still outstanding. Can someone please answer. From what I gather it should be possible using the P20 pins. Can someone please please please provide a wiring diagram for connecting P20 to SWIO, SWDLK, VDD & GND on an external board. Also explain what we are supposed to do when our external boards are powered by a 3V battery. Do we take the battery out and power it from nRF52-DK?? Asking simply because I don't have the correct connector for P19 :)
@Remi Isn't this explained in "More info here" in Wojtek's answer?
I believe the issue OP may of been having was that he's using pin 1 instead of pin 2 for VDD. This is my current setup and it's working well for programming an UNPOWERED external board.
nRF52-DK Custom / External Board
VDD ------+-------------> VDD
GND ------------+-------> GND
GND DETECT ---+
SWD IO -----------------> SWD IO
SWD CLK ----------------> SWD CLK
GND DETECT is not necessary.