*CO<sub>2</sub> Ampel* is an open-source project, written in C++ for ESP8266 or ESP32.
It measures the current CO<sub>2</sub> concentration (in ppm), and displays it on an LED ring.
The room should be ventilated as soon as one LED turns red.
## Features
The *CO<sub>2</sub> Ampel* can:
* Display CO2 concentration on LED ring.
* Allow calibration.
* Get current time over NTP
* Send data over MQTT.
* Send data over LoRaWAN.
* Display measurements and configuration on a small website.
* Log data to a CSV file, directly on the ESP flash memory.
## Hardware Requirements
* [ESP8266](https://en.wikipedia.org/wiki/ESP8266) or [ESP32](https://en.wikipedia.org/wiki/ESP32) microcontroller (this project has been tested with *ESP8266 ESP-12 WIFI* and *TTGO ESP32 SX1276 LoRa*)
* [Sensirion SCD30](https://www.sensirion.com/en/environmental-sensors/carbon-dioxide-sensors/carbon-dioxide-sensors-co2/) "Sensor Module for HVAC and Indoor Air Quality Applications"
* [NeoPixel Ring - 12](https://www.adafruit.com/product/1643)
See the [original documentation](https://transfer.hft-stuttgart.de/gitlab/co2ampel/ampel-documentation) for more info.
Or our Wiki [MakerLab Wiki CO2 Ampel](https://wiki.makerlab-murnau.de/books/co2-ampel).