For measuring rooms air quality it uses two gas sensors MQ-9 and MQ-135 also a Thermistor for measuring temperature. Displays gas value (unitless) and temperature (celsius) on a I2C 128x32 SSD1306 driver OLED display. Has a two buttons: first button -- Toggles ON/OFF the display second button -- Turns on the fans for a period of time
Circuit:
- Automatically turns the fans ON, when the air quality goes bad (user inputs the values)
- User can turn the fans for a period of time, the remaining time is displayed on the LCD
- Toggle ON/OFF the display -- Why should it run always.
watch a demo video below:
Demo video link
only one sensor in demo :(
- For measuring temperature with a Thermistor, Steinhart–Hart equation was used
- for the OLED display u8x8 library was used