Air Quality

What the air in the room is actually doing. An SCD40 measures CO2, temperature and humidity, and a BH1750 measures illuminance. Both sit on the CYD's CN1 connector - one I2C bus, two addresses, four wires. Two automations watch the CO2 reading: past 1000 ppm the verdict turns red and asks you to open a window, and back under 800 it goes green again. The gap between the two thresholds is deliberate, so a reading hovering on the line does not flicker. The SCD40 only produces a new sample every five seconds or so, which is why it is polled at that rate rather than faster. It is drawn as an instrument: a seven-segment reading over its own unlit segments, which is a second label behind the first saying 8888. The marker on the colour scale is a slider with nothing drawn but its knob, riding a scale that is in the backdrop.