There are a lot of temperature sensors that can be used, but for this project we will use a very common one, the DTH22. It can measure temperature and humidity.
The following are the DHT22 characteristics:
- Low cost
- 3 to 5V power and I/O
- 5mA max current used during conversion (while requesting data)
- Good for 0-100% humidity readings with 2-5% accuracy
- Good for -40 to 125°C temperature readings ±0.5°C accuracy
- No more than 0.5 Hz sampling rate (once every two seconds)
- Body size 15.1mm x 25mm x 7.7mm
- 4 pins with 0.1" spacing
DHT22 can be found as a separate sensor or as a breakout. It is preferrable to buy the breakout version since it has also the pull-up 4k7 resistor and a capacitor. If you prefer the sensor alone this is the pinout:
DHT22 pinout
Here:
- VCC: can be between 3V3 and 5V
- GND: is the ground
- DATA: is the data pin
Don't forget to add a 4K7 pull-up resistor between the DATA and VCC pin. For the connection with a gas furnance or other heating element, a relay will be added on the...