
Overview
The sensor consists of an IR LED and a photo sensor (phototransistor). The light emitted by the IR LED gets reflected by any object placed in front of the sensor and this reflection is detected by the photo sensor (phototransistor). Any white (or lighter) colored surface reflects more than black (or darker) colored surface.
When the reflected light is detected, it produces Digital HIGH (or Binary 1) output on the Sig pin. The on-board LED indicator will also glow. If no reflection is detected or if the object is too far from the sensor, the output on the SIG pin stays at Digital LOW (Binary 0). The on-board LED indicator will be off as well.
The detectable range of this sensor is 4–16 mm. The module incorporates a Rail-to-Rail Operational Amplifier to amplify the output of phototransistor. There is a potentiometer which can be used to adjust the gain of the amplifier, that is, sensitivity of detection.
Get Inspired

By popular demand, we are pleased to announce that it’s now possible to buy the Arduino MKR IoT Carrier. Originally forming a key part of the Arduino Oplá IoT Kit, we’ve responded to our community to make the carrier available on its own, thus enabling you to benefit from having a bunch of sensors, actuators, and a display all featured on the one board — making it quicker and easier to take your IoT projects to the next level. Featuring a large set of built-in sensors and actuators as well as a useful color display, the carrier lets you focus on prototyping your IoT ideas right away by saving on the hassle of wiring and soldering these components. The carrier can become a WiFi, LoRa, NB-IoT or GSM-compatible device by seamlessly connecting to any MKR family board. Building a user interface for these boards is easy with the embedded color OLED screen, five capacitive touch buttons, and the five RGB LEDs. The integrated sensors (temperature, humidity, pressure, RGBC light, gesture and proximity) allow you to map the environment around the carrier, and should you need to capture any other data there are over 100 additional Grove sensors that can easily be connected directly to the carrier. Here’s are quick demo of the carrier's capabilities! (Special shout out to Mirko Pacioni and Filo Connesso for creating this demo.) Capture and store all the data locally on an SD card, or connect your MKR family board to the IoT Cloud for real-time data captured, storage, and visualization. The MKR IoT Carrier features: Round OLED displayFive RGB LEDsFive capacitive touch buttonsOn-board sensors (temperature, humidity, pressure, RGBC light, gesture and proximity)BuzzerIMU (Three-axis accelerometer sensor and three-axis gyroscope sensor)Two 24V relaysMicroSD card holder (SD card not included)Plug-and-play Grove connectors for external sensors — two analog and one digital (I2C)18650 Li-ion rechargeable battery holder (battery not