Make: Volume 78

M4 microcontroller, with a FeatherWing OLED

display and FeatherWing data logger; he shared

his code and bill of materials at github.com/

stephanschulz/co2-monitor.

If you’d like to roll your own CO

2

device, Carter

Nelson wrote an excellent mix-and-match list of

Adafruit parts at makezine.com/go/co2-adafruit.

SOFTWARE

The CO

2

monitor can be programmed in Arduino

or ArduBlock, a visual block programming

editor that is similar to Scratch (Figure

R

).The

program consists of a loop that reads the sensor

and provides the logic for what to do based on the

sensor values, and which LED light to turn on.

The code for the CO

2

Traffic Light can be

downloaded ...