DHT11 Temperature and Humidity Sensor

The DHT11 Temperature and Humidity Sensor senses, measures and regularly reports the relative humidity in the air. It measures both moisture and air temperature. Relative humidity, expressed as a percent, is the ratio of actual moisture in the air to the highest amount of moisture air at that temperature can hold.The warmer the air is, the more moisture it can hold, so relative humidity changes with fluctuations in temperature.

Humidity sensors detect the relative humidity of the immediate environments in which they are placed. They measure both the moisture and temperature in the air and express relative humidity as a percentage of the ratio of moisture in the air to the maximum amount that can be held in the air at the current temperature. As air becomes hotter, it holds more moisture, so the relative humidity changes with the temperature.

DHT11 Temperature and Humidity Sensor

Hardware Connections  

  • Vcc to 5V of arduino
  • Gnd to Gnd of arduino
  • Dout to A0(Analog 0 pin) of arduino

Specifications

PCB Size 22.0mm X 20.5mm X 1.6mm
Working voltage 3.3 or 5V DC
Operating voltage 3.3 or 5V DC
Measurement range 20-95%RH;0-50℃
Resolution 8bit(temperature),8bit(humidity)
Compatible interfaces 2.54 3-pin interface and 4-pin Grove interface(1)

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Difference between DHT11 and DHT22

Two versions of the DHT sensor, they look a bit similar and have the same pinout, but have different characteristics and specifications:

DHT11

Ultra-low cost
3 to 5V power and I/O
2.5mA max current use during conversion (while requesting data)
Good for 20-80% humidity readings with 5% accuracy
Good for 0-50°C temperature readings ±2°C accuracy
No more than 1 Hz sampling rate (once every second)
Body size 15.5mm x 12mm x 5.5mm

DHT22

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 125°C temperature readings ±0.5°C accuracy
• No more than 0.5 Hz sampling rate (once every 2 seconds)
• Body size 15.1mm x 25mm x 7.7mm

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