CircuitMess-Ringo-firmware is built using PlatformIO.
git clone https://github.com/CircuitMess/CircuitMess-Ringo-firmware
cd CircuitMess-Ringo-firmware
git submodule update --init
Install a PlatformIO IDE.
Open CircuitMess-Ringo-firmware in your IDE, and build and/or upload code from there, after connecting Ringo via USB.
Install the PlatformIO CLI according to their documentation.
# build firmware only, output in .pio/build/lolin32/firmware.bin
pio run
# OR build and install new firmware, simply connect Ringo via USB first
pio run -t upload