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ESP32 Family Microcontroller

The requirement is an ESP32 Family microcontroller with at least 4 megabytes of flash memory. The microcontroller can be any of the following:

The breadboard development assembly instructions are written from the assumption that an ESP32-WROOM-32 board is being used.

Pressure, temperature and humidity sensor

The supported sensors at this time are:

These sensors provides temperature, pressure and humidity readings. It can be substituted with a GY-BMP280 if required. The BME280 is presently in short supply.


The supported display is an SSD1306 connected via I2C.

Support for ST7735 & ST7789 is planned as a priority

The display is used to enable secure WiFi provisioning and to display live readings.

CO2 Sensor

Senseair Sunrise

The Senseair Sunrise is an excellent sensor and has been a primary focus of testing and development due to its recognised use is premium commercial devices.

This sensor can be connected either via I2C or UART. At present the UART implementation is considered most stable and should be preferred.

Cubic CM1107/CM1106

Cubic are reported to produce high quality sensors and has full support for these sensors. However as all testing has been performed on second hand units, it is impossible to comment further.

Winsen MH-Z19B/C & MH-Z14

The Winsen MH-Z19B/C sensors are fully supported and tested "functionally". Results may vary but it is worth noting that:

The MH-Z14 sensor has been lightly tested in an extremely limited fashion.

Enclosure and Electrical Connections

Breadboards are useful for experimental builds. An alternative such as soldering to a PCB or just jumper leads is also effective and more appropriate for long term use devices.

However for simplicity the assembly instructions assume breadboard are being used. Each build requires two mini-breadboards to be able to access all the relevant pins on the components.