DHT22 Digital Temperature and Humidity Sensor

Description

The DHT22 Humidity / Temperature Sensor Module uses a 1-wire interface to report both humidity (0 – 99.9%) and temperature (-40 – 80°C).

PACKAGE INCLUDES:

• DHT22 Humidity / Temperature Sensor Module
• 3 x Female / Female jumper cable for connecting the module to a microcontroller.

KEY FEATURES OF DHT22 HUMIDITY / TEMPERATURE  MODULE:

• Reports humidity over range of 0% to 99.9%
• Reports temperature over range of -40°C to 80°C
• Uses 1-Wire interface
• 3.3 and 5V logic compatible

This module utilizes the DHT22 which is a combined humidity and temperature sensor assembly.  Note that AM2302 is just another name sometimes used for the DHT22 and you may see this marking on the module.

The DHT22 sensor is capable of reading humidity over the full range of 0 to 99.9% with an accuracy of +/- 2% and temperature over the range of -40 to 125°C with an accuracy of +/- 0.5°C.   The humidity accuracy increases to +/-5% at temperature extremes.

The device does have a minimum sampling time of 2 seconds so the sensor cannot be polled more often than every 2 seconds or bad data may be retrieved.

Module Connections

The module has a 3-pin header on the assembly.

1 x 3 Header

• ‘+’  =       Connect to 3.3V to 5V.
• OUT  =  Digital sensor I/O – Connects to a digital pin on a microcontroller
• ‘- ‘  =       Connect to system ground.  This ground needs to be in common with the microcontroller.

The sensor is written and read via a single digital pin and requires the use of a library for the communications.  With an Arduino, the DHTLib library can be downloaded from the Arduino site or GitHub.

Parameters of the temperature and humidity sensor DHT22

• Sensor AM2302 (DHT22)
• Supply voltage: from 3.3 V to 5.5 V
• Average current consumption: 0.2 mA
• Does not require additional external components
• 3 x female-female wires – included
• Module dimensions: 44 x 16 x 10 mm
• Temperature
  • Measurement range: -40 to +80°C
  • Resolution: 8-bit (0.1 °C)
  • Accuracy: ± 0.5 °C
  • Response time: on average – 2 seconds
• Humidity:
  • Measuring range: 0 – 99.9 %RH
  • Resolution: 8-bit (±0,1 %RH)
  • Accuracy: ±2 %RH*
  • Response time: on average – 2 seconds

Details in the documentation.

*RH – relative humidity is expressed in percentages. It is the ratio of actual humidity in the air to the maximum number that air can keep at a given temperature.