DHT22 Temperature-Humidity Sensor

Overview

• The DHT22 is a basic, digital temperature and humidity sensor compatible with most microcontrollers including the Arduino
• It uses a capacitive humidity sensor and a thermistor to measure the surrounding air, and spits out a digital signal on the data pin (no analog input pins needed). Its fairly simple to use, but requires careful timing to grab data.
• The only real downside of this sensor is you can only get new data from it once every 2 seconds, so when using our library, sensor readings can be up to 2 seconds old.
• Simply connect the first pin on the left to 3-5V power, the second pin to your data input pin and the right most pin to ground.
• Although it uses a single-wire to send data it is not Dallas One Wire compatible!
• If you want multiple sensors, each one must have its own data pin! Download an Arduino library with example code
• Comes with a 4.7K – 10K resistor, which you will want to use as a pullup from the data pin to VCC.

Specifications

• Low cost
• 3 to 5V power and I/O
• 2.5mA max current use during conversion (while requesting data)
• Good for 0-100% humidity readings with 2-5% accuracy
• Good for -40 to 80°C temperature readings ±0.5°C accuracy
• No more than 0.5 Hz sampling rate (once every 2 seconds)
• Body size 27mm x 59mm x 13.5mm (1.05″ x 2.32″ x 0.53″)
• 4 pins, 0.1″ spacing

Resources

• DHT22 Datasheet
• DHT22  Arduino library and example code
• Tutorial on Usage of the DHT22