Fanstel USB840-nRF52840 High voltage supply mode - Vdd issue.

[Sujitth]

Hello Support,

We are using a nRF52840 based module-BT840F used dongle USB840F from Fanstel and facing Vdd setting to 3.3V failed issue.

The nRF52840 is used in High voltage mode, please refer the schematic to confirm:

After chiperase vdd is falling to 1.8V and we are not able to set it basck to 3.3v using the following command provided in Fanstel documentation

nrfjprog --memwr 0x10001304 --val fffffff5

Please find attached the log.nrfjprog_log.txt.log

we have also tried the above command by providing external 3V supply from nRF52840-DK but having the same error.

Please help to resolve this issue.

Regards,

Sujith

[ketiljo]

The problem is most probably because the debugger can't connect at 1.8 V. You need to manually power VDD with 3.0 V to force the IO levels on the SWD pins to be higher. Then you can set the REG0 output voltage and power cycle the device. 

[Sujitth]

Thank you very much for the reply.

Yes, we have disconnected the USB connection and powered 3.0V directly to the VDD from the nRF52840-DK, but still having the same error.

Is there any other diagnostic method available to troubleshoot the issue?

[ketiljo]

Maybe write  0xfffffff5 instead of  fffffff5?