nRF52840 DK J-link not working

[GaryS]

Hi - I'm using a nRF52840 DK for the first time with my 2010 MacBook pro running OSX Sierra version 10.12.6. I have SEGGER Embedded Studio for ARM 4.12 installed and Segger J-link V6.40 tools running in /Applications/SEGGER/JLink. My DK board has a PCA10056 debugger chip v1.0.0. 

I have the Power switch on the DK board set to on, coin cell battery removed, power switch set to VDD. 

When I connect the DK board to my Mac via micro USB cable, I see LED5 blinking about once a second, and LED1 pulsating about once per 3 sec. 

The big problem I'm having is that I can't get the Segger Embedded Studio to see the DK; when I select "Connect J-Link" in the Target menu, I keep getting a "Can't connect to J-Link via USB" pop-up. 

Also, I don't consistently see a "JLINK" drive widget in my Finder window. And even when I do see it and tell Segger ES to connect to the board, it ejects the JLINK drive and fails to connect as it does in all other cases. 

Any ideas?

Thanks. 

[AndreasF]

Hi.

I think you might have put your nRF52840 DK in Bootloader mode, can you check if the board shows up as "BOOTLOADER", and if it does, copy this file(J-Link OB-SAM3U128-V2-NordicSemi 170724.bin )to the "BOOTLOADER" folder, turn the power of the board off and on, and it should work.

Best regards,

Andreas

[Gireesha]

@Andreas Thanks 

This works !!!!

and to put the device to the boot loader mode fallow the below procedure

1.While holding down the boards reset button, connect the boards USB debug port to the computer. It should enumerate as BOOTLOADER or MAINTENANCE.

2. In a terminal execute

• cp <path to firmware file> <BOOTLOADER> && sync