Ruuvi Firmware version 3. Built on top of Nordic SDK 15, uses both Ruuvi and external repositories as submodules. Under development, not recommended for anything.
Download from Nordic and unpack here, or unpack someplace else and update makefile SDK_ROOT
to point at right folder.
git submodule update --init --recursive
Follow this Ruuvi blog post.
Run make in targets/board/armgcc
Flash to your board using nrfjprog or similar.