Devices stuck in high current debug mode.

RE: Devices stuck in high current debug mode.

erickcinco — Fri, 25 Jun 2021 19:47:38 GMT

A bit late of a response. My team encountered this issue a couple months ago. We found it to be a bug in the driver for the JLINK Debugger we were using to program. Ultimately it was fixed by updating past v10.9.0 of the nRF Command Line Tools which updated the JLINK drivers.

This was our experience of how the issue manifests:

If the reset after programming flag is enabled and the programming pins are removed before the reset is completed at just the right time a JLINK error is generated and the JLINK will be glitched. Any subsequent programming would then cause target devices to remain in high current (3mA) debug mode. Only a full power cycle of the JLINK debugger returned the debugger to a safe state.

We were able to reproduce this consistently after realizing what glitches the JLINK.

The change notes for nrf-command-line-tools v10.9.0 states it has been fixed.

I would add a check for any errors returned by nrfjprog and power cycle your JLINK if anything arises.

I would also power cycle your target device right after programming and before casing up as a precaution.

RE: Devices stuck in high current debug mode.

mikeg78 — Mon, 05 Aug 2019 09:44:05 GMT

I have a similar problem with a battery powered device that has debug pins exposed but no way of disconnecting the battery without damaging the device. How is a debug reset performed? I have found that shorting the debug pins to ground followed by the reset pin does not consistently get the chip out of this 3mA state, nor does the device consistently enter this state after programming. Is this a silicon bug?

RE: Devices stuck in high current debug mode.

Susheel Nuguru — Mon, 11 Feb 2019 11:19:33 GMT

Sorry, my bad, I have tried to dig a bit more on this. It need to be a power cycle or brown out reset. You can do a debug reset from the SWD pins but you do not have access to that. So there are no other way other than powre cycle and BOR unfortunately.

RE: Devices stuck in high current debug mode.

modles — Mon, 11 Feb 2019 08:53:46 GMT

Could there be an undocumented way to get the SW-DP to de-assert CxxPWRUPREQ?

RE: Devices stuck in high current debug mode.

modles — Fri, 08 Feb 2019 15:26:36 GMT

I'm afraid this does not reduce the current. Only a power cycle seems to reduce the power usage. So my feeling is its the SWJ-DP not the Debug you highlight.

RE: Devices stuck in high current debug mode.

Susheel Nuguru — Fri, 08 Feb 2019 12:53:08 GMT

If you do not have access to the device, then i think only below two options are left for you

Watchdog reset and a Pin Reset.

!) watchdog reset, you can initialized and enable the watchdog only once (based on a persistent variable) will reset the device only one and on the wakeup will never start the watchdog.

2) pull the reset pin low as configured in NRF_UICR->PSELRESET[0] and PSELRESET[1]

RE: Devices stuck in high current debug mode.

modles — Thu, 07 Feb 2019 20:03:46 GMT

Basically I need to find a way to shutdown/reset the DAP via firmware!