nRF52-DK Non-responsive

[Emlyn]

I have been using a NRF52-DK board to develop a BTle solution for the past week.
Today, midway through a debug session, the board vanished from my BT interfaces.

It also no longer shows up on USB when plugged in, neither directly or when attempting to put into DFU mode (holding the reset button down and powering on over USB).

Is there something in software I can do, or is this a hardware fault somewhere?

LED5 is not on.

Nothign is seen on USB.

[Turbo J]

Old DK hardware with the ST debug MCU chip? Hold reset when powering up, put interface MCU firmware on the drive that appears. You need to do this every time you held reset down when powering up, its quite annoying.

The newer HW revision with the NRF5340 debug MCU has a different upgrade procedure IIRC.

[Emlyn]

This is the new DK. It can be flashed with a J-link to the pins under the label, but I don't have a J-link handy.

[PaKa]

Note: If you attach a j-link to reprogram the On Board Debugger (nRF5340) to the pins under the label then you will brick the DK and it won't be recoverable so that is a hard NO.

Normally these kind of issues is caused by USB connectivity issues so check cable and connector on the DK.

[Emlyn]

The device appears to be bricked already. Are you saying that with the new boards, there's no way to re-flash the firmware if the device is non-responsive over USB?

Does this only apply to the app processor?
devzone.nordicsemi.com/.../program-a-nrf52-dk-with-another-nrf52-dk

There's also random questionable things like this too: https://gist.github.com/cszuo/22a08e3263fcfd397bf9bd91ce5168b0

[PaKa]

The first case is for programming the nRF52 on the board, that is still OK with the new board. What you can't do is program the nRF5340 debugger chip.

The second looks to be is how to recover the nRF52 if you have locked it and want to reprogram it, again it's for the nRF52 so OK. 

We do not see cases where there is a need to reprogram the nRF5340 on the DKs, the issues are "always" something else that has happened. The common issues are incorrectly set switches, USB cable, PC side issues (both USB HW and driver SW), mechanical damage to the DK, USB connector. No chance of ESD damage? 

Couldn't see any but have you by chance modifed any of the cutstraps? Not uncommon to see questions about non-functional boards where this is forgotten :-)

[Emlyn]

The board has not had any switches / cutstraps changed. Is there something I should / could try here?

It was happy as a clam until it wasn't - but I was seeing the BTle connection for a bit with my software, flashed via the debug chip and using RTT.

I don't see how ESD could have happened with mat and wrist strap- also never had an issue here previously.

I've tried a few different cables and PCs and the behaviour is the same- on insertion of the cable, there's a brief flash on LED5 and then off.

[Asbjørn]

Hello Emlyn,

Thank you for the picture of the kit. It's not a common issue, but with the number of kits we do have in the market, sometimes things do go wrong. Unfortunately it can come down to board switches set incorrectly (hence the picture request), often it is related to USB port and cable along with non-windows environment. Some then try to peel of the sticker and re-program the On Board Debugger. As indicated by Paal below here as well.

• Did you try to reprogram the ODB on the kit through the JTAG header under the sticker?
• The behaviour you're describing does indicate that the FW on the nRF5340 ODB has been changed and this isn't something we have a clear path understand on how it could be. What sort of OS environment are you working with? What versions of Segger SW and tools are you using?

Best regards

Asbjørn

[Emlyn]

Hello Asbjørn,

No, I did not try to reprogram the ODB. I don't have a J-Link other than this broken board.
My questions down this path were whether it could be recovered this way though another J-link, but that seems not to be the case.

I was running a BTle app on the application processor, using softdevice 132. 
RTT viewer 9.62
nRF Connect Desktop 5.3.2, programmer 4.8.0
Windows 11, 64 bit

[Asbjørn]

Hi Emlyn, 

I should have asked you in a previous reply, but what are you measuring on the VBUS input to the ODB nRF5340? 

See the red arrow for the location of the R9, C35 and C36 cap on the VBUS input. When the cable and everything is plugged in, what voltage are you measuring there on these three components?

Best regards

Asbjørn

[Emlyn]

5.18V on the bottom pads of the two left most components (R/C) and 0V on the bottom of the right component of the three (the other cap).

Resistor is measuring 2ohms, 
Top pads of the two caps measure zero 

So:

5.18     0       0
   |        |        |

5.18   5.18    0

A full schematic would be helpful to diagnose.
The P1 VDDs have 3v reading