Attributes

Brand	-
Category	Robotics / STEM Teaching Tools / Sensors
Origin	-
Model Number	AHT21B
Measurement Range (Temperature)	-40°C to +85°C
Measurement Range (Humidity)	0% to 100% RH
Accuracy (Temperature)	±0.3°C
Accuracy (Humidity)	±2% RH
Communication Interface	I2C
Supply Voltage	2.2V to 5.5V DC
Response Time	< 8 seconds
Package Type	SMD Module
Application	HVAC, Smart Home, Industrial Monitoring

6 reviews

Anonymous

Mar 31, 2026

Rating: 4/5

Good value, fast shipping

The module works as described. Humidity response is quick. Only giving 4 stars because the documentation could be slightly more detailed regarding register maps, but standard libraries work fine.

Anonymous

Mar 26, 2026

Rating: 5/5

Highly recommended

This is my go-to sensor for any project requiring environmental data. The integration is seamless, and the data consistency over time is impressive.

Anonymous

Mar 24, 2026

Rating: 4/5

Solid performance

Works right out of the box. The soldering pads are large enough for hand soldering if you don't have a reflow oven. Readings match my expensive benchtop unit within expected tolerance.

Anonymous

Mar 22, 2026

Rating: 5/5

Low power consumption

Great for battery-powered IoT devices. The sleep mode current is incredibly low, allowing my device to run for months on a single coin cell.

Anonymous

Mar 22, 2026

Rating: 5/5

Perfect for agricultural monitoring

We deployed twenty of these in our prototype greenhouse system. They handle the high humidity environment well without drifting. Very reliable for the price point.

Anonymous

Mar 19, 2026

Rating: 5/5

Excellent precision for hobby projects

I integrated this sensor into my home weather station and the readings are consistently accurate compared to my calibrated reference meter. The I2C communication is stable and easy to implement with Arduino.

5 FAQ

Q: Does this module come with a protective filter?

A: The standard module includes a basic dust filter. For environments with heavy particulate matter or corrosive gases, we recommend adding an external membrane filter.

Q: What is the maximum cable length for the I2C connection?

A: For standard I2C speeds (100kHz), we recommend keeping cables under 30cm for optimal reliability without pull-up resistor adjustments. For longer distances, consider using an I2C extender or buffer.

Q: Can I use 3.3V logic levels?

A: Absolutely. The sensor operates between 2.2V and 5.5V, making it directly compatible with both 3.3V and 5V microcontroller logic levels without a level shifter.

Q: How often should I calibrate this sensor?

A: The AHT21B is factory calibrated and typically maintains accuracy for years under normal operating conditions. Recalibration is generally only necessary if the sensor is exposed to extreme conditions beyond its specifications.

Q: Is this compatible with Raspberry Pi?

A: Yes, the AHT21B uses the I2C protocol which is fully supported by Raspberry Pi GPIO pins. You will need to enable the I2C interface in the raspi-config settings.

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