Adafruit
Adafruit HTS221 - Temperature & Humidity Sensor Breakout Board
The Adafruit HTS221 is an affordable I²C/SPI temperature and humidity sensor breakout board from ST. It measures relative humidity from 0–100% RH with 3.5% a...
The Adafruit HTS221 is an affordable I²C/SPI temperature and humidity sensor breakout board from ST. It measures relative humidity from 0–100% RH with 3.5% accuracy (in the 20–80% range) and temperature from -40 to 120°C with ±0.5°C accuracy (between 15 and 40°C). An excellent choice for everyday environmental monitoring applications.
The breakout includes STEMMA QT / Qwiic connectors for solderless I²C hookup, along with standard header pins for breadboard use. On-board level shifting and a voltage regulator make it compatible with both 3.3V and 5V microcontrollers.
Key Features
- 0–100% Relative Humidity Range – 0.004% sensitivity, 3.5% accuracy (20–80% RH)
- -40 to 120°C Temperature Range – 0.016°C resolution, ±0.5°C accuracy (15–40°C)
- I²C and 3-Wire SPI Interfaces – Flexible connectivity options
- STEMMA QT / Qwiic Connectors – Solderless I²C connection, compatible with SparkFun Qwiic
- 3.3V and 5V Compatible – On-board level shifting and voltage regulation
- Arduino and CircuitPython Libraries – Ready-to-use driver support with example code
Ideal For
- Indoor climate and environmental monitoring
- Greenhouse and mushroom farming humidity tracking
- Weather station projects
- Beginner-friendly sensor projects with solderless STEMMA QT connection
Package Contents
- 1× Adafruit HTS221 Breakout Board – Assembled and tested with STEMMA QT connectors
- 1× Header strip (unsoldered)
Resources
Jargon buster
Plain-language definitions for the technical terms used above.
- breakout
- A breakout is a small circuit board that makes a tiny or hard-to-solder component easier to connect to with standard pins. It matters because this OLED module can be wired into a microcontroller project without needing to solder directly to the display’s fine contacts.
- CircuitPython
- A beginner-friendly version of Python designed to run directly on microcontroller boards. If a product supports CircuitPython, you can often program it by copying code files onto the board rather than setting up a more complex toolchain.
- Qwiic
- Qwiic is a plug-in connector system for I2C devices that uses small 4-pin cables, so you can connect compatible sensors without soldering. It matters because your controller or adapter also needs Qwiic, or you will need a cable or breakout to wire it up.
- SPI
- A fast serial communication bus often used for displays, memory cards, and sensors. It matters because SPI devices need specific pins for clock and data, plus a separate chip-select line for each device.
- STEMMA
- A plug-and-cable connection system used on some maker electronics boards to make wiring simpler. If a product uses STEMMA, you need the matching cable or connector type to plug it in without soldering.
- STEMMA QT
- A small plug-in connector system for I2C boards that lets you connect compatible sensors and controllers without soldering. It matters because it can make wiring faster and less error-prone, especially when adding several small modules to a project.
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