Yet another CO2-Ampel based on an ESP8266 (Wemos D1 mini) to continuously measure CO2 concentration indoors with a SCD30 CO2 sensor accompanied by a BME280 for temperature, humidity and air pressure readings. Current air condition (good, medium, critical, bad) is shown using a NeoPixel ring with WS2812 LEDs illuminating the device in either green, yellow or red.

Unlike other devices this one runs on two 18650 Li-Ion batteries, offers a sophisticated web interface for configuration, live sensor readings and OTA firmware updates. Sensor data can be logged to local flash (LittleFS), retrieved RESTful, published using MQTT or even transmitted with LoRaWAN if a RFM95 shield is installed.