# esp32-co2-scd4x
This project displays the current co2 levels, along with temperature and humidity information, on a HD44780 16x2 display. All of this is powered by an ESP32 devkit and a SCD40/41 photoacoustic NDIR CO2 sensor.

## Wiring
![Wiring diagram](img/wiring.jpeg)

The main components here are wired up like this:
- The green, yellow and red LEDs are connected to ground and pins 25, 33 and 32 respectively
- The HD44780 16x2 display is connected to an I2C daughterboard, which itself is connected to +5V, ground, as well as the I2C bus pins of the ESP32, 22 for clock and 21 for data
- The SCD40/41 photoacoustic NDIR CO2 sensor is connected to +5V and ground for power and to pins 22 and 21 (ESP32 I2C_bus1; MH-Z19B side pins SCL and SDA respectively)
- A button to toggle the backlight is connected between pin 23 and ground

## Setup
The device will open a WiFi hotspot on first boot, connecting to which reveals a setup dialog for WiFi information, OpenWeatherMap API key & coordinates (this is for collecting pressure information to feed to the SCD4x sensor)