NRF52 bricked with CONFIG_GPIO_AS_PINRESET and P0.21 tied to ground?

[Thomas N.]

Dear Nordic Team,

Due to a mistake i flashed a bootloader-firmware with the compile flag CONFIG_GPIO_AS_PINRESET onto a custom board where pin P0.21 is tied to ground.

Now the nrfjprog output says:

nrfjprog -f nrf52 --program _build/nrf52811_xxaa.hex --sectorerase
ERROR: Cannot connect to any nRF device. Please make sure a device is
ERROR: connected to the debugger and supplied.
make: *** [flash] Error 42

When trying to connect with JLinkExe the output is:

Connecting to target via SWD
Found SW-DP with ID 0x2BA01477
Found SW-DP with ID 0x2BA01477
Could not power-up debug power domain.
Scanning AP map to find all available APs
AP[0]: Stopped AP scan as end of AP map has been reached
Iterating through AP map to find AHB-AP to use
Found SW-DP with ID 0x2BA01477
Found SW-DP with ID 0x2BA01477
Could not power-up debug power domain.
Scanning AP map to find all available APs
AP[0]: Stopped AP scan as end of AP map has been reached
Iterating through AP map to find AHB-AP to use

Can this board be considered as bricked, or is there a way to recover from this state?

Many Thanks

[Turbo J]

Try the  --eraseall or --recover options for nrfjprog.exe - it looks to me like reset is not connected when UICR is fully erased.

[Thomas N.]

Hi,

Thanks for the quick answer. Unfortunately all IC related nrfjprog switches return "Segmentation fault: 11"

I found a post about a similar issue, though the author there did not explain how he solved the issue:
https://devzone.nordicsemi.com/f/nordic-q-a/51089/nrfjprog-10-3-0-segfault

[RK]

I suspect he was able to disconnect P0.21 from ground and that's how he solved it. You of course don't have that option. 

The only thing I can think of you might try is using the CTRL-AP port to reset and erase the entire chip and UICR. That's what --eraseall does however I think perhaps the code there doesn't like the actual chip being in reset. If you read this thread https://devzone.nordicsemi.com/f/nordic-q-a/12484/approtect-and-dap you'll find the commands for using JLink to directly access the CTRL-AP port without attempting any real connection, it just sends simple SWD commands directly. No iterating access points or anything. 

If that doesn't work, I think you're bricked. It is not unlikely that reset is a very global signal which holds everything in the entire chip in reset until deasserted, that may well include the CTRL-AP port, unless someone cleverly thought about this kind of issue. You might want to try the above process several times just incase reset clears after a number of cycles on SWD on the AP. 

[haakonsh]

RK said:

If that doesn't work, I think you're bricked. It is not unlikely that reset is a very global signal which holds everything in the entire chip in reset until deasserted

I'm afraid this is true, it's a global HW reset state where CPU and HW state machines are halted.

The only way to un-brick your device is to sever your reset pin's connection to ground. 

[Thomas N.]

Trying to use the CTRL-AP port seemed promising but you are right. The only way to get the board the work again, was to disconnect the reset pin from ground.