Can't flash nRF52840. Unable to connect to a debugger.

[AlexanderOhm]

Hi!
We have a custom board and when ordering a new version we now get Errors on two of the 18 prototypes.

After trying on another machine with another JLink one of the two problematic boards passed without issue, but for the other one the problem was reproducable.
Any help would be much appreciated!

When trying nrfjprog --reset we get:

ERROR: Unable to connect to a debugger.
ERROR: JLinkARM DLL reported an error. Try again. If error condition
ERROR: persists, run the same command again with argument --log, contact Nordic
ERROR: Semiconductor and provide the generated log.log file to them.
NOTE: For additional output, try running again with logging enabled (--log).
NOTE: Any generated log error messages will be displayed.

We also tried --recover, to no avail.

log file from --log:
8475.log (1).log

[Simonr]

Hi

So now it is only one nRF52840 custom board that is having this issue, correct? The log file only shows generic "unknown" errors unfortunately which usually points to the target not being powered correctly, so my initial guess would be that either the nRF52840 is incorrectly soldered on or that it is a faulty device. What J-Link device exactly are you using for programming these boards, and what voltage are the boards powered with here?

Best regards,

Simon

[AlexanderOhm]

We just got an x-ray of the board and can confirm there were soldering issues. Thanks!

Perhaps it's an Ezurio/Laird question, but are there any tips and tricks re. soldering the BL654 module? This is the second board house we've used that has issues. I can't find anything in the datasheet besides the reflow heat profile.

[Simonr]

Hi, check out the circuit board guidelines or the QFN soldering reflow guidelines whitepapers available here.

Best regards,

Simon