1. Download NRF52 SDK 15.2 link
2. Clone repo
3. Fix path to sdk in Makefile:

SDK_ROOT := ..

PROJ_DIR := .

4. Configure Device: make sdk_config

• Select Light sensor, ISL29035 (hardware v3 or 3.1) or OPT3001 (hardware v3.2)
• Enable/Disable "Low Bat sleep", relevant when powering the board from SWD

5. Flash Softdevice make flash_softdevice
6. Flash App make flash