SparkFun
Qwiic Soil Moisture Sensor
· MPN: SEN-24409
This compact breakout board measures moisture in soil and similar materials using two large exposed pads as conductivity probes. As the soil gets wetter, con...
This compact breakout board measures moisture in soil and similar materials using two large exposed pads as conductivity probes. As the soil gets wetter, conductivity between the pads increases, resistance drops, and the sensor produces a higher analog SIG output.
For quick setup, the board includes a Qwiic connector and an onboard ATtiny85 MCU that acts as an I2C gateway. You can plug it into a compatible Qwiic ecosystem without soldering, or use the broken-out programming pins for standard I2C or SPI access.
The sensing leads use an Electroless Nickel Immersion Gold (ENIG) finish to help protect the contact area in wet, muddy environments. SparkFun also provides documentation including the schematic, Eagle files, hookup guide, Qwiic resource page, Arduino library, Python / MicroPython / CircuitPython libraries, and hardware repository.
Features:
- Plug-and-Play I2C: Connect the sensor to your compatible development ecosystem without ever touching a soldering iron.
- Broken-Out Pins: If you haven't adopted the Qwiic ecosystem yet, or if you want to reprogram the MCU yourself, we have fully broken out the programming pins so you can easily interface using standard I2C or SPI protocols.
- I2C Jumper: If you plan to chain multiple Qwiic devices on the same bus, the board includes an easily accessible I2C jumper on the back that you can cut with a hobby knife to disable the pull-up resistors.
- Variable resistor/conductivity-based moisture sensing
- Electroless Nickel Immersion Gold (ENIG) Finish on sensing leads
- Onboard ATtiny85 handles analog-to-I2C conversion
- Broken-out programming pins for SPI or standard I2C, plus an adjustable I2C pull-up jumper
- Output: Simple analog signal (SIG) out based on moisture levels
- I2C Address: 0x28
- 1x Qwiic Connector
Specifications:
- Moisture sensing: Variable resistor/conductivity-based moisture sensing
- Sensing lead finish: Electroless Nickel Immersion Gold (ENIG) Finish on sensing leads
- MCU: Onboard ATtiny85 handles analog-to-I2C conversion
- Programming pins and pull-up jumper: Broken-out programming pins for SPI or standard I2C, plus an adjustable I2C pull-up jumper
- Output: Simple analog signal (SIG) out based on moisture levels
- I2C Address: 0x28
- Qwiic Connector: 1x Qwiic Connector
A practical sensor for automated gardens, smart greenhouses, desk planters and other plant-monitoring projects using Qwiic-compatible boards.
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.
- I2C
- I2C is a two-wire communication bus used by many sensors and small modules. It matters because several I2C devices can share the same two wires, but each device needs a compatible address and your controller must support I2C.
- I2C address
- An I2C address is the number a device uses so a microcontroller can tell it apart from other devices on the same I2C bus. It matters because two devices with the same fixed address may conflict if used together.
- MicroPython
- A version of the Python programming language made to run on microcontrollers. It matters because it lets beginners write readable code to control LEDs, sensors, motors and displays without needing to start with lower-level languages.
- 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.
Find this product in
Brands
Sensors & Input
Qwiic Soil Moisture Sensor Schematic
Schematic · 183.0 KB · Click any page to view full size
Supplier page — sparkfun.com
Supplier Description · 1.3 MB · Click any page to view full size
Resources & Downloads
Guides, code examples, and more
