nRF52 Preview DK v1.1.x

Interface MCU firmware (FW)

The on-board interface MCU is factory programmed with an mbed-compliant bootloader. This makes it possible to update the SEGGER J-Link OB interface firmware.

For more information on entering the bootloader mode, see IF Boot/Reset button.

To update Interface MCU firmware, drag the Interface image (.bin) into the mounted bootloader drive on the connected computer and power cycle the board. It is also possible to download the latest SEGGER J-Link software from SEGGER J-Link Software and open a debug session in order to automatically update to the latest J-Link OB firmware version.

The J-Link OB image can be downloaded from

Important: When in bootloader mode, do not drag and drop any file except those downloaded from for use with the Interface MCU. If a wrong file is used, it can overwrite the bootloader and ruin the Interface MCU firmware without the possibility of recovery.