nRF52 DK v2.X.X no longer allows Debug Out for external supplies below 2V

RE: nRF52 DK v2.X.X no longer allows Debug Out for external supplies below 2V

Vidar Berg — Tue, 20 Oct 2020 11:23:15 GMT

The debug output works with 3V logic so I think you must have been lucky with the old DK you had. I have not been able to program targets at 1.8V with the few v1.x.x boards I have tested. The standalone J-links come with a built-in level shifter to support different target voltages.

RE: nRF52 DK v2.X.X no longer allows Debug Out for external supplies below 2V

WoutEcto — Mon, 19 Oct 2020 13:38:23 GMT

We also have a J-Link lying around which we use for the higher volume, more formal stuff. The nRF52-DK as debugger was mainly to debottleneck things and try out some new stuff and it stuck around because it just works. At least it did up till the new hardware version. I guess it's time to invest in some additional J-Links then.

RE: nRF52 DK v2.X.X no longer allows Debug Out for external supplies below 2V

awneil — Mon, 19 Oct 2020 13:27:13 GMT

Having seen that warning, I didn't even try to use the debug out on a 1.8V project - just went straight to a proper J-Link.

AIUI, the nRF52-DK senses the target Vdd at Debgug Out, and uses that to switch the SWD connection from the onboard nRF52 to the external target.

So I guess it must be the thresholds in the sensing stuff that have changed ... ?

EDIT

other debug probes are available.

RE: nRF52 DK v2.X.X no longer allows Debug Out for external supplies below 2V

WoutEcto — Mon, 19 Oct 2020 13:19:34 GMT

Thanks for showing this information. I'm definitely talking about the nRF52 DK (with nRF52832). I must have not checked this information because I wasn't aware that this was only supported for 3V external supplied MCUs. I also never needed to check this, because it just worked on our devices with the nRF52832 supplied by 1.8V. It's only now that we switched to this newer hardware version of nRF52 DK that this issue became apparent.

I guess since the 3V support limit is stated in the documentation it's not a bug or anything like that, but I'm interested to find out what changed between v1.x.x and v2.x.x. that could lead to this behavior.

RE: nRF52 DK v2.X.X no longer allows Debug Out for external supplies below 2V

awneil — Mon, 19 Oct 2020 13:05:15 GMT

AFAIK, the nRF52 DK has never supported debug out at other than 3V

I think the nRF52840-DK might?

EDIT