Line Follow Sensor

The line following sensor can detect light or dark areas in close proximity. There are 2 sensors, allowing a reading on the left and right.

The line following sensor is primarily used to create line following robots.

Line Follow Sensor

What is it

The line following sensor is actually made up of two light sensors and two lights:

Code

The light is an Infrared (IR) light. This is a light that can’t be seen by humans, but can be detected by an IR sensor. The light will reflect off a white surface, but with darker surfaces, less light is reflected. A totally black surface will not reflect any light. The IR detector will detect this difference in reflected light.

Code

Wiring

Use a special cable to connect the sensor. This has 4 wires, white, pink, red and black:

line follow cable

Wire up as follows, using the Edge Connector or Motor Controller board:

Numeric Display	Microbit	Purpose
Red	3V3	Power
Black	GND	Ground
Pink	P1	Left sensor
White	P0	Right sensor

On the Motor Controller Board it should look like this:

Code

Coding

Enter this code in the forever block:

Code

Download the code to the microbit.

The code creates reads the left and right sensor and shows the values in the data window.

To see the data, click on Show data Device:

Code

You should see some numbers and a graph. These show the amount of light falling on the sensor:

Code

Move the sensor over a black line about 1cm thick on a white sheet of paper. Notice how the left and right readings change, with high values when the sensor is over a white area and low values with the sensor is over a dark area:

line_follow

By comparaing the two values you can find out where the line is.

This sensor is used in the line following robot activity.