I have an early nrf52840-Preview-DK device that has worked fine before.
When the project is revisited the board is no longer detected in any of the programs in nrf Connect for Desktop v3.9.3.
I have flashed the Interface MCU firmware binary J-Link OB-SAM3U128-V2-NordicSemi 170724.bin from https://www.nordicsemi.com/Products/Development-hardware/nrf52840-dk/download#infotabs
The nrf52840 loads binaries using the Segger J-Link drive and works ok.
The device is found using the nrf Command Line nrfjprog.exe -i and reports number 683920827, same as on the device MPU printed label.
I guess the nrf Connect no longer supports windows 7, but stated in the documentations for the programmer - https://infocenter.nordicsemi.com/pdf/nRF_Connect_Programmer_User_Guide_v1.0.pdf
Have tested in both 64 and 32-bit environments with device not detected.
The device also exposes a serial port so it seems the nrf Connect is not as able as it where in earlier versions.
What to do next?
