Adafruit
Adafruit LTR-329 Light Sensor - STEMMA QT / Qwiic
The Adafruit LTR-329 is a low-cost I2C digital light sensor that provides 16-bit measurements for both infrared and visible+IR spectrums. Subtract one from t...
The Adafruit LTR-329 is a low-cost I2C digital light sensor that provides 16-bit measurements for both infrared and visible+IR spectrums. Subtract one from the other to get human-visible light readings. With configurable gain and integration time, it can measure from 0 to over 65,000 lux — suitable for everything from dim indoor lighting to bright sunlight.
This is the simpler, lower-cost sibling of the LTR-303 — same core light sensing capability but without the interrupt/alert feature. This STEMMA QT breakout includes voltage regulation and level shifting for both 3.3 V and 5 V systems.
Key Features
- Dual-Spectrum Sensing – 16-bit measurements for both infrared and visible+IR light
- Wide Lux Range – 0 to 65,000+ lux with configurable gain and integration time
- I2C Interface – Simple two-wire communication
- STEMMA QT / Qwiic – Solderless I2C connectors for easy plug-and-play wiring
- 3.3 V and 5 V Compatible – Onboard voltage regulator and level shifting
- Arduino & CircuitPython Libraries – Ready-to-use drivers with example code
Ideal For
- Automatic display brightness adjustment
- Day/night detection and light-based automation
- Light-following robots and solar trackers
- Environmental monitoring and data logging
Package Contents
- 1× Adafruit LTR-329 Light Sensor Breakout (STEMMA QT)
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.
- 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.
- integration time
- Integration time is how long the sensor collects light for each measurement. Longer times can improve readings in dim light, while shorter times can respond faster or avoid saturation in bright light.
- IRQ
- Short for interrupt request, a signal pin a device uses to get a microcontroller’s attention when something needs handling. It matters here because I2C communication with the sensor requires connecting the IRQ pin to a suitable input pin.
- lux
- Lux is the standard unit for measuring how much light falls on a surface, similar to how a light meter reports brightness. A sensor that outputs lux gives readings that are easier to compare between rooms, outdoor conditions, and different projects.
- 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.
- 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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Brands
Sensors & Input
Related Tutorials
Free guides on learn.littlebird.com.au
