Airhat is an air quality monitoring station. It's a functional moke-up and hit on a prototyping board, raspberry hat format (56x65mm). It haves two smart sensors, with serial port interface :

SDS021 laser based fine particle sensor, MH-Z19 NDIR carbon dioxide sensor.

Because Raspberry Pi only have one asynchronous serial interface, i added an SC16IS752 dual UART over SPI IC from NXP semiconductors. Why such station and why these two sensors ? My daily road trip to work is quite long. I wanted to know was was the incoming pollution inside my car. But it's also quite useful at home. When open windows ? Now i can say i feel better when carbon dioxide is under 800 part per million inside my house.

You'll find in this deposit datasheets of sensors, some pieces of firmware and more in the future.

You can see this moke-up in action at : https://www.youtube.com/watch?v=5Mh0E2QSfTs

You can also follow nadhat google+ collection : https://plus.google.com/collection/EejeRE

Have fun.

Frederic Pierson