No connection with nRF52840 DK from PC via USB (J2)?

[KPC_Lunav]

Hi,

I saw a similar post (Case ID: 249969) and this just happen to me.

I have not used my nRF52840 DK for a few weeks. It has been in its original plastic bag the whole time. Connected it today and nothing happen (no light on LED5), no responds from Windows that it connected. I also plugged in a nRF52 DK on the same USB cable and that "turned" on, LED blinking and I could connect to it with the nRF Connect application (v3.3.3) and programer v1.4.2.

made sure it was like below:

I checked power on TP11 and TP12 - found 5V as expected. I also checked other TPs and found 3.19V (TP31) and 4.65V (TP32).  Also measured 2.98V on VDDnRF and same on TP7.

So I'm very curious on what has happen with my nRF52840 DK?

Could it be something wrong with the interface MCU? IF BOOT/RESET button?

Any suggestion would be appreciated.

best regards,

Peter 

[Simonr]

Hi again

Can you try to completely power cycle your board? Turn the ON-OFF button off, remove the battery, and USB cable, before inserting the cable and try powering it back on. You can also try another USB cable to confirm that it's not a bad cable that is the problem.

If you still don't see any life signs, I think your board might be bricked somehow.

Best regards,

Simon

[KPC_Lunav]

Hi Simon,

I have done complete power cycle with no battery, no USB and several different USB cables. Still no connection to J-LINK.

The whole board is not "bricked" as the nRF52840 was flashed with a program a few weeks back and this is running as normal - i.e. it is a Bluetooth mesh node and it pops up in the nRF Connect app on my phone and on my MQTT broker. 

So it looks like the J-LINK interface is "bricked".

Is there anything we can do with the IF BOOT button or other hacks to get it back to normal?

Kind of need to flash a bunch of nRF52840 boards....

Peter