Introduction: How to Build a Mouse Trap Using Arduino

About: Just an ordinary 14 year old with interest in electronics.

Hello guys ! Hope you are having an awesome time ! Now the reason I am writing this Instructable is a long story. Well I will make it short. I had hid some of my favorite snacks in my cupboard to hide it from my sister. It was a pretty hard place for finding by any one. But I was wrong :( . A mouse which had a good sense of smell had got into my cupboard ate up all my favorite snacks. I told this thing to my mom but all I got was a long lecture since I had hid it from my sister. So I had to take things into my own hand. That is where I had this idea to build a mouse trap using Arduino and publish it to make sure you guys don't have to face my problem again.

Step 1: Stuff You Might Need

So we are going to arrange a grand party for the mouse(I mean a grand trap)isn't it ? These are the things you might need :

  • Arduino
  • Breadboard
  • Jumper wire
  • servo motor
  • 330 ohm resistor x2
  • ultrasonic sensor
  • led x2
  • buzzer
  • double sided tape

Step 2: The Connections

Now let us make connections for the mouse trap. There are many things you could improve in this connection like adding a PIR motion sensor ( if the mouse is very cunning ! I have a really good experience about that). Now let me explain how the sensor works(yup, this is for science freaks, if you are not one skip to the fourth paragraph).

Let us start with an ultrasonic sensor. There is a trig pin on the ultrasonic sensor. It sends an ultrasonic sound(sound that has a frequency above 20000Hz ) to an obstacle. When the sound hits an objects it reflects the sound back and it falls on the eco pin. Then the sensor measures the amount of time take for the sounds to come back. then you can convert it into centimeters or inches using the code.

Now the led. An led is also known as a light emitting diode (learning this will be helpful if you are planning to sleep in your physics class) . Now the advantage of led over other lights is that it glows even in a low current and also lasts for a long time.

Now for the connection. You have to get two leds a green one and a red one(please feel free to take any other color). The positive terminal of the the green led (the long terminal)is connected to digital pin 6 in arduino. The red pin of the led is connected to digital pin 5. The pins of the ultrasonic sensor(trigpin and echopin) is connected to the the digital pins of arduino. The trig pin is connected to the digital pin 7 and the echo pin to pin 8. The positive terminal of the buzzer is connected to digital pin 10. Please refer the diagram for further explanation.

Step 3: The Bodywork

So are you ready to make that mouse a piece of history? So let us start mission "mouse out of house" ! Now to start with you need a big bottle(a cardboard box will also do).

STEP 1: Cut a hole in the bottle for the ultrasonic sensor(make sure you cut it in such an angle that when the ultrasonic sensor is mounted it can sense anything in the box).

STEP 2: Cut the bottom of the bottle. Now cut it carefully because you should not cut it completely. make sure you should leave some part of the bottom uncut(that is going to be the lock). Please refer picture 2 to be clear.

STEP 3: Cut a piece of cardboard to make a door. Make sure it is of the right length or else the mouse will escape.

STEP 4: Now using a double sided tape attach the servo to the end of the door.Then attach the door to the servo. Just give a trail to make sure the door will open and close smoothly(see picture 2).

STEP 5; Place the ultrasonic sensor in the hole (picture 4).

STEP 6: Now do the connections and you are ready to go !

Step 4: The Code:

Now for the coding. Well what this code does is that when a mouse gets inside the trap the servo rotates 180 degree thus closing the door. Then the green light turns off and the red light turns on. The buzzer is also activated. So now the code is written below:

#include <Servo.h>//include the servo library
int redpin = 5;//name digitalpin 5 as redpin(it is our red led)

int greenpin = 6;//name digital pin 6 as greenpin(it is our green led)

int trigpin = 7;//name pin 7 as trigpin

int ecopin = 8;//name pin 8 as ecopin

Servo servo1;//name our servo as servo1

int distance, duration;//make two variables named distance and duration

int buzzer = 10;//name pin 10 as buzzer

void setup() {

// put your setup code here, to run once:

pinMode(redpin, OUTPUT);//set redpin as output

pinMode(greenpin, OUTPUT);//set greenpin as output

pinMode(trigpin, OUTPUT);//set the trigpin of ultrasonic sensor as output

pinMode(buzzer, OUTPUT);//set the buzzer as output

pinMode(ecopin, INPUT);//set the echopin of ultrasonic sensor as input

servo1.attach(2);//attach the servo to pin 2


void loop() {

// put your main code here, to run repeatedly:

digitalWrite(trigpin, LOW);//activate the trigpin

delayMicroseconds(2000);//activate the trigpin

digitalWrite(trigpin, HIGH);//activate the trigpin

delayMicroseconds(15);//activate the trigpin

digitalWrite(trigpin, LOW);//activate the trigpin

delayMicroseconds(10);//activate the trigpin

duration = pulseIn(ecopin, HIGH);//define the duration

distance = (duration/2)/29.1;//define the distance (don't worry if you didn't understand the code all it does is that it //converts the time into distance

if(distance <=15 )//if the distance is less than 15 cm then


digitalWrite(redpin, HIGH);//turn the red led on

digitalWrite(greenpin, LOW);//turn the green led off

servo1.write(180);//turn the servo 180 degree

digitalWrite(buzzer, HIGH);turn the buzzer on




digitalWrite(greenpin, HIGH);//turn the green led on

digitalWrite(redpin, LOW);//turn the red led off

digitalWrite(buzzer, LOW);//turn the buzzer off

servo1.write(0);//turn the servo to zero degree



So that is all for the code now upload this to your arduino and it will do the trick. Also make sure that you keep your mouse trap in a corner because mice have a habit of going around the corner. Also keep some thing for him to eat also, that will also attract him. So mission "mouse out of house" is complete. Now who is in with me for a pizza with extra mozzarella cheese