RE: nRF52 DK debug out via P19

Stian Røed Hafskjold — Thu, 16 Mar 2017 12:40:49 GMT

In the user guide for the DK:

Important: The voltage supported by external debugging/programming is 3.0 V.

However, I tried flashing a device that was powered with 1.8V now, and it worked. I can't guarantee that it will always work because of the statement in the user guide.

EXT_GND_DETECT should be connected to GND of the external device. And that should be it. VTG, GND, SWDIO and SWDCLK.
You don't have to connect the SWO signal.

RE: nRF52 DK debug out via P19

butch — Wed, 15 Mar 2017 21:55:58 GMT

Not an answer, because I am not sure. 1) When I do it, I power the proto from 2 AAA cells, so I don't think the voltage difference matters. 2) and 3) I use 5 lines, the first three you mention, plus GND and EXT_GND_DETECT. I don't connect SWO and never use it (I don't know what it does for you. I use Segger RTT for logging.) I think the connections are discussed elsewhere on this forum.