Arduino - Light Sensor Triggers Servo Motor

In this tutorial, We are going to learn how to use light sensor and Arduino to control the servo motor. In detail, Arduino reads value from a light snesor:

If the light sensor's analog value is greater than a threshold, Arduino rotates the servo motor to 90 degree
If the light sensor's analog value is lower than a threshold, Arduino rotates the servo motor back to 0 degree.

Hardware Required

1	×	Official Arduino Uno
1	×	Alternatively, DIYables ATMEGA328P Development Board
1	×	USB 2.0 cable type A/B (for USB-A PC)
1	×	USB 2.0 cable type C/B (for USB-C PC)
1	×	Light Sensor
1	×	10 kΩ Resistor
1	×	Servo Motor
1	×	Jumper Wires
1	×	Recommended: Screw Terminal Block Shield for Arduino Uno
1	×	Recommended: Breadboard Shield for Arduino Uno
1	×	Recommended: Enclosure for Arduino Uno
1	×	Recommended: Prototyping Base Plate & Breadboard Kit for Arduino UNO

Or you can buy the following sensor kits:

1	×	DIYables Sensor Kit (30 sensors/displays)
1	×	DIYables Sensor Kit (18 sensors/displays)

Disclosure: Some links in this section are Amazon affiliate links. If you make a purchase through these links, we may earn a commission at no extra cost to you.
Additionally, some links direct to products from our own brand, DIYables .

The LDR light sensor is very affordable, but it requires a resistor for wiring, which can make the setup more complex. To simplify the wiring, you can use an LDR light sensor module as an alternative.

About Servo Motor and Light Sensor

If you do not know about servo motor and light sensor (pinout, how it works, how to program ...), learn about them in the following tutorials:

Wiring Diagram

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Arduino Code - Analog Threshold

/* * Created by ArduinoGetStarted.com * * This example code is in the public domain * * Tutorial page: https://arduinogetstarted.com/tutorials/arduino-light-sensor-triggers-servo-motor */ #include <Servo.h> // constants won't change const int LIGHT_SENSOR_PIN = A0; // Arduino pin connected to light sensor's pin const int SERVO_PIN = 9; // Arduino pin connected to Servo Motor's pin const int ANALOG_THRESHOLD = 500; Servo servo; // create servo object to control a servo void setup() { servo.attach(SERVO_PIN); // attaches the servo on pin 9 to the servo object servo.write(0); } void loop() { int analogValue = analogRead(LIGHT_SENSOR_PIN); // read the input on analog pin if (analogValue > ANALOG_THRESHOLD) servo.write(90); // rotate servo motor to 90 degree else servo.write(0); // rotate servo motor to 0 degree }

Quick Steps

Connect Arduino to PC via USB cable
Open Arduino IDE, select the right board and port
Copy the above code and open with Arduino IDE
Click Upload button on Arduino IDE to upload code to Arduino
Rotate the light sensor
See the change of servo motor

Video Tutorial

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Function References

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