AHT21B Temperature Humidity Sensor Module - I2C High Accuracy
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AHT21B Temperature and Humidity Sensor Module – I2C Interface, ±2% RH Accuracy
The AHT21B is a digital temperature and humidity sensor module using the I2C protocol. It delivers accurate measurements with a typical accuracy of ±2% RH for humidity and ±0.3°C for temperature. Designed for low-power applications, this sensor is ideal for environmental monitoring, weather stations, and IoT data logging.
Key Specifications
| Specification | Value |
|---|---|
| Supply Voltage | 2.2V – 5.5V DC |
| Humidity Range | 0% to 100% RH |
| Temperature Range | -40°C to +85°C |
| Humidity Accuracy | ±2% RH (typical) |
| Temperature Accuracy | ±0.3°C (typical) |
| Interface | I2C (address 0x38) |
What You Can Build With This
- Indoor weather station with real-time display
- Greenhouse or terrarium climate monitor
- Incubator or mushroom farm humidity controller
- Server room temperature and humidity alert system
Compatibility
This module works with any microcontroller supporting I2C, such as Arduino Uno, Nano, ESP32, ESP8266, and Raspberry Pi. The AHT21B runs from 2.2V to 5.5V, and its I2C pins follow its supply. Power it from the same voltage as your board's logic: 3.3V for ESP32, ESP8266 and Raspberry Pi, 5V for Arduino Uno.
Wiring Notes
Connect VCC to 3.3V, GND to ground, SDA to the I2C data line (A4 on Arduino Uno), and SCL to the I2C clock line (A5 on Uno). The module includes built-in pull-up resistors, so external resistors are not required. Keep wires short and avoid noise sources for stable readings.
Why Buy from Compoden
Every component is sourced from verified suppliers and tested for compatibility before listing. We've spent 10 years building projects for makers, schools, and institutions across India. Ships from Bengaluru in 3-7 days. If defective on arrival, replace within 7 days.
Is this compatible with Arduino?
Yes, the AHT21B uses I2C and works with Arduino boards. Use the AHTxx library for easy interfacing. On a 5V Arduino, power the module from 5V so its I2C levels match.
What is the sampling rate?
The sensor provides a new reading approximately every 2 seconds (0.5 Hz). It is not suitable for high-speed applications but perfect for periodic environmental logging.
Can it be used outdoors?
The bare module is not waterproof. For outdoor use, house it inside a weather-proof enclosure with a breathable membrane to allow humidity sensing while protecting from direct moisture and dust.
📦 Free Setup Handoff Document Included
Every Compoden order includes a free setup handoff document — step-by-step instructions to get your component working within minutes. Download it via QR code on your package. The handoff document is also trained to help you troubleshoot the majority of problems.
Ask Soldr above what you can build with this — it knows every Compoden kit this part appears in.
Shipping Information
- Prepaid Orders: ₹75 for orders up to ₹999, FREE shipping above ₹999
- COD Orders: ₹125 shipping + ₹50 COD fee = ₹175 total
- Delivery Timeline: Dispatch in 3-7 days, delivery in 2-7 days depending on location
Returns & Warranty
- 7-Day Return: Manufacturing defects only (approval required)
- Warranty: 7 days from delivery
- Non-Returnable: Batteries, consumables, cut wires, clearance items
The official datasheet / documentation for this part:
View Datasheet