Could not power-up debug power domain.

[janwillemp]

I was building a prototype on my nRF52DK. Before the weekend it all worked fine, switched it off, came back after the weekend and now I get the "Could not power-up debug power domain." when I try to program it.

It came to life just once after I had pulled all the wires out and blew some dust off it, but when I then hooked everything back up it was dead again and stayed dead.

I hooked up an external nrf52832 and could program it fine, so I guess I fried my on board '52.

Before I hook up the same circuit to the external nrf52, I'd like to understand why I fried it. I have this sensor with AC input of up to 8.6Vpp and about 500kHz. I ran that through a rectifier, which leaves me with a blocky DC waveform with Vmin at 0V and Vmax at about 3V. Added a 0.1uF smoothing cap to get a steady 3V output, 4.05uA. This was directly connected to both a digital and an analog input (for application's reasons), and GND. That can't surely have fried my nrf52 can it?

Are there things to try to possibly recover the chip or should I just consider it lost?

[MartinBL]

If your ADC input stays below VDD+0.3V your input voltage shouldn't be a problem. Note that the nRF5s on the DK kits often run at ~2.8V due to some protection diodes on the kit.

I see there are a few similar reports on this forum , but they all seem to discuss external devices.

[janwillemp]

thanks. The 8.6Vpp I wrote earlier likely was a measurement error. I set the whole thing up again using an external board and now have 4Vpp AC which converts to about 2.9Vpp DC (1.1V rectifier drop).

Is there another (preferably physical) way I can test whether or not the nRF52 on the DK is broken? And where can I verify the 2.8V, is there a test point somewhere?

[MartinBL]

1. The most accessible point to measure Vdd_nRF is probably on Pin1 on P22 (the current measurement header).
2. If you have a second debugger you could try to hook it up to the 'Debug In' header (P18) on the DK and try to program the nRF52.

BTW: You can find layout and hw files that you can use to look for test points etc. here.

[janwillemp]

Strangely enough it came back to life a few days ago, but yesterday, after having to take it for a bumpy bike ride, it died on me again, so it looks like a bad connection somewhere. I guess I'll have to buy a new one.