ESP8266 Family Microcontroller
The requirement is an ESP8266 Family Microcontroller with at least 4 megabytes of flash memory.
Pressure, temperature and humidity sensor
The supported sensors at this time are:
- Bosch BME280
- Bosch BMP280
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.
Display
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 AirNeter.io has full support for these sensors. However as all testing has been performed on second hand units AirMeter.io, 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:
- These sensors generally require forced background calibration.
- Voltage and quality of power supply maybe important.
The MH-Z14 sensor has been lightly tested but has not been deeply investigated and tested.
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.