DHT22 Digital Temperature and Humidity Sensor Module

DHT22 Digital Temperature and Humidity Sensor Module (AM2302) is a highly accurate and reliable sensor that provides calibrated digital outputs for measuring both ambient temperature and relative humidity. Consequently, this sensor excels over simpler alternatives like the DHT11, offering superior stability, precision, and a wider measurement range. The DHT22 utilizes a capacitive humidity sensor and a thermistor, transmitting the measured data via a single-wire digital interface, which drastically simplifies the integration process with microcontrollers such as Arduino and Raspberry Pi. Furthermore, its low power consumption and robust design make it an ideal choice for long-term data logging and remote environmental monitoring projects, where precise and stable readings are critical. Therefore, designers frequently select the DHT22 module to capture environmental data in demanding applications.

Key Features:

• High Accuracy: Delivers superior accuracy, with humidity measurements typically within ±2% RH and temperature measurements within ±0.5°C.
• Digital Output: The single-wire bidirectional digital signal drastically simplifies the communication protocol, requiring only one data pin on the host microcontroller.
• Wide Measurement Range: Offers a broad operational range, measuring humidity from 0% to 100% RH and temperature from −40°C to +80°C.
• Factory Calibrated: The sensor is calibrated in a high-accuracy humidity chamber and stores calibration coefficients in its OTP memory, minimizing the need for user calibration.
• Low Power Consumption: It features low current draw in measurement mode and ultra-low current in standby mode, which is ideal for battery-powered or energy-efficient devices.

Technical Specifications:

• Supply Voltage (V_CC): 3.3 V to 5.5 V DC
• Humidity Range: 0 ∼ 100% RH
• Humidity Accuracy: ±2% RH (Typical)
• Temperature Range: −40°C ∼ +80°C
• Temperature Accuracy: ±0.5°C (Max)
• Resolution: 0.1 for both temperature and humidity
• Sampling Rate: Maximum 0.5 Hz (One measurement every 2 seconds)
• Output Signal: Digital (Single-wire protocol)

Mechanical Specifications:

• Sensor Element Type: Capacitive Humidity Sensor and NTC Thermistor
• Module Style: 3-pin or 4-pin module with housing for easy installation.
• Housing Material: High-quality ABS Plastic (often white or blue)
• Lead Material: Standard male header pins for breadboard or PCB mounting.

Dimensions:

• Module Body Length: ≈ 25.0 mm
• Module Body Width: ≈ 15.0 mm
• Module Body Height: ≈ 7.0 mm (Excluding pins)
• Pin Pitch: 2.54 mm (0.1 inch standard)
• Weight: ≈ 2.5 g (Lightweight for portable applications)

Pinout and Wiring:

• Pin 1 (VCC): Connect the VCC pin to the positive power supply (3.3V or 5V).
• Pin 2 (Data): This pin transmits and receives data. Connect it to a digital I/O pin on the microcontroller. A 10kΩ pull-up resistor to VCC is generally required if the module does not include one.
• Pin 3 (NC/Null): This pin is typically reserved or unconnected (NC) on the 4-pin version and often missing on the 3-pin module.
• Pin 4 (GND): Connect the GND pin to the circuit ground (0 V).
• Wiring Note: Ensure you use a quality library for the specific microcontroller (e.g., Adafruit DHT library for Arduino) to handle the critical timing requirements of the single-wire protocol accurately.

Datasheet Reference:

• Download DHT22 (AM2302) Digital Sensor Datasheet

Commonly Used in:

• Hobbyist Projects: A popular choice for DIY weather stations, smart home projects, and environmental monitoring systems using Arduino or ESP32.
• HVAC Systems: Integrated into low-cost air quality and climate control monitoring solutions for residential and light commercial use.
• Data Logging: Used in devices that continuously log temperature and humidity in server rooms, greenhouses, and storage facilities.

Applications:

• Weather Station Development: Capturing ambient conditions for local weather reporting systems.
• Terrarium/Incubator Monitoring: Precisely regulating and monitoring the internal climate for optimal animal or plant health.
• Dew Point Calculation: Providing the necessary raw data (Temperature and RH) to calculate the dew point accurately.
• Home Automation: Triggering humidifiers, dehumidifiers, or air conditioning units based on room conditions.

Equivalent Models:

• SHTxx Series (e.g., SHT31, SHT40): However, these modern I²C sensors offer higher precision and faster response times but typically come at a higher cost.
• DHT11: The lower-cost, lower-accuracy predecessor to the DHT22 (AM2302).
• BME280: A combined temperature, humidity, and barometric pressure sensor; conversely, it uses the I²C/SPI protocol, not the single-wire interface.

Package Includes:

• 1 x DHT22 Digital Temperature and Humidity Sensor Module (AM2302)