nrf52840 - Not working with J3 and LED1,2,3, and 4 are blinking

[ArunRuchir]

We are trying to use nrf52840DK for the Openthread FTU unit. While we are able to flash the Hex file, upon changing the USB cable to J3, it's not getting recognized under the USB connection (ttyACM???), and all 4 LEDs (LED1,2,3 and 4) start blinking continuously (not very bright - just 5%). 

Is this a Hardware defect or some solution to solve it? 

[Naeem Maroof]

Hi

Thank you for contacting DevZone at NordicSemi.

1) Is it the same usb cable that you have used for programming, and now you are connecting from J2 to J3?

2) Or you are using another cable for J3?

Apparently, from your description, I would suggest to check the state of SW9 and SW6.

To power through USB via J3, SW9 should be on USB_Source side

If you want to only power the SoC, then switch SW6 to nRF_Only

Please check the power sources and operating modes in the DK user guide: nRF52840_DK_User_Guide

Regards,

Naeem

[ArunRuchir]

Dear Naeem,

Thanks for your response. To your questions:

1) Yes. Same cable. Just shifted the connection from J2 to J3. 

2) No. Same cable. 

SW9 - is on USB Power

SW6 is on Default

We have 2 DK boards (newly purchased) and both have identical switches and other positions. One is working fine and this one is having the above-mentioned issues. This one is not getting recognized on serial tty* also. A video enclosed for the issue. 

Please suggest a solution or help with the replacement of this defective board. 

Thanks.  

[Naeem Maroof]

Hi Arun,

Thank you for sending more information.

As per your case where you have 2 DKs, and 1 is working perfectly fine while the other is showing these symptoms.

I am assuming that you are powering both DKs the same way, and the configuration of the switches (SW9 and SW6) are also the same.

In such a case, this could be problem in the DK. However, may I suggest to directly connect the DK to the computer without USB hub and see if it works.

BR,

Naeem

[ArunRuchir]

Thanks, Naeem,

Have sought replacement of DK board. Hope this problem will not come in new hardware. 

Thanks for your help. 

Regards

Arun