nRF52 DK Debugger Dead? Any recovery?

[FI]

Worked fine until yesterday. Board turned off with computer, also the power switch on the board was in off position before turned on this morning. Now the debugger circuit/IC does not respond, no more programmer LED, computer does not recognize this board, nothing happens when plugged in or power cycled in Windows and Linux, no more USB device load. The nRF52 parts of the boards still works fine, with Serial output, IO toggles and Scanning LED blinking as programmed since last load. Briefly checked supplies, 5V, 3.3V and 3V present on the board. My other nRF52 DK still works OK.

Are there any trouble shoot and recovery for the on board debugger?

Thanks!

FI

[FI]

Though it just sit on my desk from the last good point and this morning, I wanted to understand what happened, so my other good nRf52 DK board would not have issues and set me back:

• All the supplies to the Atmel are checked out, including the 1.8V. So the Atmel chip is seeing supply.
• USB input protect seems fine, compared measurement with the other good board.
• Diodes for the 3.3->3V are functional, as the 3V supply is present everywhere.
• USB detect is regulated from 5V to 3.3V, and SH_VTG has no active drive, so the 10K pulls PB5 point low.
• Tried nrfjprog -d, -e, --recover, no success -> ERROR: There is no debugger connected to the PC. Do not have much experience with other tools yet. Nordic is new to me.
• Tricked USB detection on Windows by using few hundred Ohms and pulled up the D+ or D-, Windows detects, but no communication and driver can not be loaded. Forced a driver but that did not help. Note that, this Segger USB setup is MCU dependent, if the D+ or D- is not pulled for Windows to detect, the device is considered disconnected.
• Xtal is not toggling, by just looking on the scope with few pF of probe load. Not sure this is a measurement issue and what to expect, or the internal oscillator comes on first to configure.

Are there other tools and techniques I should try? Not sure to use JLink.exe si 1 r h w4 4001e504 2 w4 4001e50C 1 w4 4001e514 1 r, as this was suggested for nRF51, in this post: devzone.nordicsemi.com/.../

I do not have any other compatible Segger programmers, thought about using an Arduino IDE and see whether that could flash the Atmel maybe with a FTDI. Really want to get some input before I do more damages.

Any help would be appreciated, this is a problem for me, and I'd really like to get a good handle on it, either understand what not to do, or have a way to get it functional again, most importantly to prevent this from happening.

Thanks!

FI

[Kenneth]

Hi, Maybe you can try to follow the nRF52 DK user guide, in specific check out how to enable Bootloader mode and program the SEGGER J-Link OB interface firmware again.

[FI]

Thanks Ken,

I tied this method, it did not put the interface MCU to bootloader mode, and LD5 did not come up to indicate. Seems like the firmware in the frontend MCU is corrupted somehow. It is a mystery. Thank again.