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Description: The Si7021 is a low-cost, easy-to-use, highly accurate, digital humidity and temperature sensor. This sensor is ideal for environmental sensing and data logging and perfect for build a weather stations or humidor control system. All you need are two lines for I2C communication, and you’ll have relative humidity readings and very accurate temperature readings as a bonus!

There are only four pins that need to be hooked up in order to start using this sensor in a project. One for VCC, one for GND, and two data lines for I2C communication. This breakout board has built-in 4.7KΩ pullup resistors for I2C communications. If you’re hooking up multiple I2C devices on the same bus, you may want to disable these resistors.

Note: Full drops of water can damage the sensor. We recommend wrapping the board in Teflon/irrigation tape for extreme conditions where water droplets may find their way onto the sensor.

Dimensions: 0.6" x 0.6"


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Customer Comments

  • I’m trying to hook this up and I’ve tried it on a couple of different boards; Nano and and Uno. They both display the same thing serial monitor.

     Temp:-51.85F, Humidity:-5.81%

    Am I hooking it up wrong? Bad board? Any thoughts on how to get it up and running?

    Thanks Rich

  • Hi, what was the reason for replacing the HTU21D breakout with this si7021 board? What are the differences? A quick look at the datasheets indicate the HTU21D is more a cure and consumes less power than the si7021. Please correct me if I’m wrong. I’m guessing these sensors are related since the similar part number and seem pinout compatible. Will the same software that worked with HTU21D work with si7021? Thanks, keep up the good work :-)

    • Primary reason we moved towards the Si7021 was to get the PTFE filter. We found the HTU21D did fine indoors but many of our customers were using them in the field (and Hawaii) and needed the filter to protect the sensor from damage.

Customer Reviews

5 out of 5

Based on 1 ratings:

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Tiny, nice and simple

Very easy setup, controlled by a Raspberry Pi 2 with CE’s Python script for this module:

Highly recommended for temp and humidity in one package.

Related Tutorials

Si7021 Humidity and Temperature Sensor Hookup Guide

May 5, 2016

The Si7021 humidity and temperature sensor is an easy to use, digital, low-cost sensor to aid you in all your environment sensing needs.