Adafruit stocks a large number of Temperature/Humidity sensors, so you're probably wondering why another one? Well, this Adafruit HDC3021 Precision Temperature & Humidity Sensor breakout features the highest accuracy & precision one we've see so far!

It uses the TI HDC302x series chip with typical 0.5% accuracy for the RH sensor (with 0.19% long-term drift) and ±0.1°C typical accuracy for the temperature sensor. All at a very nice price.

This sensor has a true I2C interface for easy interfacing with only two wires (plus power and ground!). That makes it preferable to the janky DHT11/DHT22 sensors.

 The sensor is 5V safe, so you can use 1.8V to 5V power and logic levels without the need for shifters, so you can power and communicate with it using any microcontroller or microcomputer.

With 4 selectable I2C addresses, you can have multiple sensors on one bus - unlike many other fixed-address T/RH sensors.

We've written full-featured Arduino and CircuitPython / Python libraries, so whether you have an 8-bit microcontroller or a quad-core Raspberry Pi, you will be able to quickly get data from the sensor for your environmental monitoring needs. The libraries can setup the sensor rate/power, heater, alerts, offsets, and read data or NIST tracking ID.

Such a lovely chip - so we spun up a breakout board with the HDC3021 and some supporting circuitry such as pullup resistors and capacitors. To make things even easier, we've included SparkFun Qwiic compatible STEMMA QT connectors for the I2C bus so you don't even need to solder! QT Cable is not included, but we have a variety in the shop.

If you prefer working on a breadboard, each order comes with one fully assembled and tested PCB breakout and a small piece of header. You'll need to solder the header onto the PCB, but it's fairly easy and takes only a few minutes even for a beginner.

Please note: this sensor comes with a protective polyamide sticker on top, please remove before usage!