PCA10056 Not working

[vishal.roy]

Just bought 2 nrf52840 DK's both stopped working

Observation

• Was able to program and run SDK examples.
• Above working setup not disturbed,so all cables are in order verified that
• The current problem i have:
  1. when I connect the DK to PC the device is not shown in device manager initially.After awhile it pops up
  2. When I try to flash it fails and LEDs switch of and come back up.
  3. The board had the blinky example code.So if from Step 1 I toggle IF Boot/Reset switch I can see the UART logs in terminal.
  4. Very weird observation is there is buzzing sound coming from the board.Can i do something to fix this issue.
  5. When I go near the switch usb/VDD/Lipo selection the entire board switches off and comes back up as a move my hand.Attached video.The buzzing sound can be heard in video
•  

[Simonr]

Hi

What application are you running on the nRF52840DK here? I just tested on a PCA10056 v2.0.1 myself and I don't see any of the issues you describe above on my side. Are both of your DKs showing the same exact issues? Are you powering your devices by USB? Is the battery still in the DK or not? Please also note if you've done any modifications to the DKs.

Please check that all switches on the DK are in the following positions:

• VEXT->nRF set to OFF
• nRF power source set to VDD
• TRACE set to Def.
• nRF ONLY | DEFAULT set to DEFAULT.

You can also try resetting the Interface MCU firmware on the DK by holding the IF Boot/Reset button while powering the device to set it in the bootloader mode, then downloading the Interface MCU firmware .bin file from here, then drag and drop that .bin file into the BOOTLOADER window that should appear when the DK is in bootloader mode. 

Best regards,

Simon

[vishal.roy]

Simonr

• I am running the blinky demo app in sdk.
• All the switched are in default state as you mentioned .
• The battery is in DK and insulator between the battery and terminal are intact as it comes with box,the device is powered via USB.There is absolutely no modification on both DKs
• I did some probing and found that the VDD is ~1.7 on power-up and slowly starts to rise(1-3 Minutes) and once above 2.5V the board boots up and Jlink is detected.
• I do not think its a segger code corruption because once the board boots up after 1-3 Minutes JLink is detected.My doubt is on some dry solder issue on one of the caps or some other components in the supply path,which could be casing the humming sound also.C92 is what I suspect

[Simonr]

Thank you for the update. I have reported this issue internally, and will keep you updated. It seems to be related to the VIO_REF pin on header P20, which will disconnect the Interface MCU if it is shorted. We are investigating this issue and will keep you updated. Please confirm the following for us:

• Are both DKs reacting the same way? That is, does both MCUs power off if you get close to the power select switch SW9?
• Does the nRF chip continue running when the MCU is turned off or not? That is, does the LED1 keep blinking while the MCU is powered off by your presence?
• Can you try to put a (plastic) cover over the VIO_REF pin on P20 and see if you still short the board when getting close to SW9?

Best regards,

Simon

[vishal.roy]

• Are both DKs reacting the same way? That is, does both MCUs power off if you get close to the power select switch SW9?
  • Both were behaving the same way but now not able to reproduce the issue on one of them.The other board still exhibits this behavior.The board which has this issue if i leave it ON for about 5 min it will start working normally after it tries by itself to boot up.Cant say is stable can go OFF any time.
• Does the nRF chip continue running when the MCU is turned off or not? That is, does the LED1 keep blinking while the MCU is powered off by your presence?
  • When the system goes down everything switches OFF.
• Can you try to put a (plastic) cover over the VIO_REF pin on P20 and see if you still short the board when getting close to SW9?
  • Tried this will attach  a video , no improvement.

[vishal.roy]