Humidity and Temperature Sensor Breakout - Si7021

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 pull up resistors for I²C communications. If you’re hooking up multiple I²C devices on the same bus, you may want to disable/enable the pull-up resistors for one or more boards. On the Si7021, the pull-ups are enabled by default. To disable them, simply use some solder wick to remove the solder on the jumper labeled PU. This will disconnect the resistors from VCC and from the I2C bus.

The Si7021 also comes equipped with a hydrophobic PTFE filter covering the inlet on the sensor. This filter blocks contaminants but allows water vapor to pass through, keeping your sensor safe from water damage while still proving accurate sensor readings.

The tiny white cover on the IC is known as a Polytetrafluorethylene (PTFE) Membrane Filter. It keeps moisture out but allows humidity in. This filter is very low-profile, hydrophobic and oleophobic, and excludes particulates down to 0.35 microns in size.

Features

• Uses the I²C interface
• Typical humidity accuracy of ±2%
• Typical temperature accuracy of ±0.3C
• Operates from 0 to 100% humidity but this sensor isn’t recommended for harsh environments where it could come in contact with water (such as rain)
• 3.3V sensor - use inline logic level converters or 10kΩ resistors to limit 5V signals
• Only one Si7021 sensor can reside on the I²C bus at a time
• Dimensions: 0.6" x 0.6"