1. Introduction
  2. Preparations
  3. About the TCRT5000 IR Track Sensor
  4. Example
  5. Connection
  6. Upload Sketch
  7. Program Running Result


The TCRT5000 IR Track Sensor is essentially an IR LED and an IR detector. It works by transmitting a beam of IR light downward toward the surface. In this lesson, we will show you how the IR Track Sensor works and how to use it with the Osoyoo Uno board.




About TCRT5000 IR Track Sensor

The TCRT5000 IR Track Sensor is essentially an IR LED and an IR detector. The IR emission tube of TCRT5000 sensor constantly emits infrared light. Since the black absorbs light, when the IR emission tube shines on a black surface, the reflected light is less and so less IR rays are received by the receiving tube. It indicates the resistance is large; then the comparator outputs high and the indicator LED goes out. Similarly, when it shines on a white surface, the reflected light becomes more. So the resistance of the receiving tube is lower; thus, the comparator outputs low and the indicator LED lights up.

When the infrared transmitter emits rays to a piece of paper, if the rays shine on a white surface, they will be reflected and received by the receiver, and pin S will output low level; If the rays encounter black lines, they will be absorbed, thus the receiver gets nothing, and pin S will output high level.

This acts like a simple switch when it gets close to a white / black object. You can adjust the sensitivity with the potentiometer. It uses a LM393 Comparator chip and TCRT5000 sensor for clean outputs.

Sensitivity: About 1 inch (2.5cm) from white paper, about 1 cm from a person's finger.


IR Line tracking

In this experiment, we will use an IR track sensor module and the on-board LED to build a simple circuit to make a tracking line. Since the LED has been attached to pin 13, connect the pin S to digital pin 2 of the Uno board. When the tracking sensor detects reflection signals (white), the LED will be on. Otherwise, it will be off (black line).

Note: The sensitivity of the infrared sensor is adjustable – you may adjust it by the potentiometer.


Build the circuit as below digram:

Code Program

After above operations are completed, connect the Arduino board to your computer using the USB cable. The green power LED (labelled PWR) should go on.Open the Arduino IDE and choose corresponding board type and port type for you project. Then load up the following sketch onto your Arduino.

const int trackingPin = 2; //the tracking module attach to pin 2
const int ledPin = 13; //pin13 built-in led
void setup()
  pinMode(trackingPin, INPUT); // set trackingPin as INPUT
  pinMode(ledPin, OUTPUT); //set ledPin as OUTPUT
void loop()
  boolean val = digitalRead(trackingPin); // read the value of tracking module
  if(val == HIGH) //if it is HiGH
    digitalWrite(ledPin, LOW); //turn off the led
    digitalWrite(ledPin, HIGH); //turn on the led

Running Result

A few seconds after the upload finishes, set it down on a piece of paper with a dark line (at least ½" wide). You may use a Sharpie Marker, electrical tape, or dark paint. When the module gets on a black line, it output high and the corresponding LED stays off; when it meets a white area, it outputs low and the LED lights up.

Note: The black line should be wider than the IR track sensor