nRF52840 DK doesn't program now and unsure why

[Justin Reina]

Hi,

 We are integrating the nRF52840 into a new test apparatus and I am using the nRF52840-DK for development. I have pulled out my unit from storage and it will not power on, I observe the following -

Observations:

• Config - SW8:On, SW9: Vdd, SW6: Default

• Cold_Power-on (Connect J2-USB to PC): No response (Device Manager or USBDeview reports)

• RESET_Power-on: (Depress IF BOOT/RESET, Connect J2-USB to PC):
  • LED5: Blink @ ~1Hz
  • Device Manager shows activity (no Ports activity), keeps resetting
  • USBDeview flashes but reports no content updates

Question:

• How do I get this unit back into development use? We have the nRF52832-DK and it works appropriately, if useful

Thoughts?

[Kenneth]

You can check if everything looks mounted correctly, and that you for instance last time did not cut or remove any components (e.g. to measure power consumption). It looks like the board doesn't enumerate, so you may look into whether you are using a proper USB cable (e.g. some charging cables don't have D+/D- USB data lines).

[Justin Reina]

I did a pass over on the board, all components are stock and in place. Also retried with a shorter USB cable, same result.

If I hold IF BOOT/RESET will connecting the USB, LED5 begins toggle which indicates bootloader mode I think, does this board need replaced?

[Justin Reina]

Here is my board -

[Kenneth]

Looks like the sticker is missing, I suspect the boards are pre-production devices then, but to confirm it would be good if you can read the small laser printings on the nRF52840 ic itself. The pre-production kits (aka. developer preview kits, PDK) were made before the chips were fully tested and qualified for mass production, and can have various issues. So I recommend to get new kit yes.

Best regards,

[Justin Reina]

It is the - 'N52840 QIAAC0 1830DJ' -

[Kenneth]

This is production silicon of the nRF52840 (QIAAC0), because last value is a digit '0', if it was a letter e.g. 'A', then it would be engineering samples. I think the board have been damaged somehow, so I recommend a new kit yes. 

Best regards,
Kenneth

[Justin Reina]

Hello Ken, thank you so much for the help! I enjoyed the process debugging with you, have picked up a new DK and in soon. The knowledge and help you shared is much appreciated  ️