Introduction: Motion/Proximity Sensor Alarm System.

I made a motion sensor that detects movement and sends alerts to the serial monitor.

Supplies

Ultrasonic Sensor, Jumper wires, Arduino uno, breadboard,

Step 1: How It Works.

The ultrasonic sensor first detects movement of nearby objects. Then if the system is armed it will show the distance in the serial monitor.

Step 2: The Code

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// Ultrasonic sensor (3-pin)
constintultrasonicPin=11;

// Distance threshold in inches
floatdistanceThreshold=10;

// Duration for pulseIn
longduration;

// Distance in inches
floatinches;

// Tracks whether the alarm is currently active
boolalarmTriggered=false;

// RGB LED, buzzer, button
constintredPin=3;
constintgreenPin=5;
constintbluePin=6;

constintbuzzerPin=7;

constintbuttonPin=9;


voidsetup()
{
Serial.begin(9600);

// Set up pins
pinMode(redPin,OUTPUT);
pinMode(greenPin,OUTPUT);
pinMode(bluePin,OUTPUT);

pinMode(buzzerPin,OUTPUT);

pinMode(buttonPin,INPUT);

Serial.println("System armed...waiting for object.");
}

voidloop()
{
// Send pulse to ultrasonic sensor
pinMode(ultrasonicPin,OUTPUT);
digitalWrite(ultrasonicPin,LOW);
delayMicroseconds(5);
digitalWrite(ultrasonicPin,HIGH);
delayMicroseconds(10);
digitalWrite(ultrasonicPin,LOW);

// Now wait for response
pinMode(ultrasonicPin,INPUT);
duration=pulseIn(ultrasonicPin,HIGH);

// Calculate distance in inches
inches=(duration*0.0133)/2;

Serial.print("Distance: ");
Serial.print(inches);
Serial.println(" in");

if(!alarmTriggered){
// If alarm is not triggered, blink yellow while waiting
blinkYellow();

// If object is within threshold, activate alarm
if(inches<distanceThreshold){
Serial.println("Object Detected!");
alarmTriggered=true;
}
}
else{
// alarm IS triggered
flashRed();
tone(buzzerPin,1000);
Serial.println("Alarm triggered.");

// Check if button is pressed to deactivate
if(digitalRead(buttonPin)==HIGH){
noTone(buzzerPin);
alarmTriggered=false;
Serial.println("Alarm deactivated.");

// Wait until object moves away
while(inches<distanceThreshold){
// Repeat pulse to check if it's gone
pinMode(ultrasonicPin,OUTPUT);
digitalWrite(ultrasonicPin,LOW);
delayMicroseconds(5);
digitalWrite(ultrasonicPin,HIGH);
delayMicroseconds(10);
digitalWrite(ultrasonicPin,LOW);
pinMode(ultrasonicPin,INPUT);
duration=pulseIn(ultrasonicPin,HIGH);
inches=(duration*0.0133)/2;

delay(100);
}

Serial.println("System re-armed.");

delay(1000);
}
}
}

voidsetColor(intred,intgreen,intblue){
analogWrite(redPin,red);
analogWrite(greenPin,green);
analogWrite(bluePin,blue);
}

voidblinkYellow()
{
setColor(255,255,0);
delay(500);
setColor(0,0,0);
delay(500);
}

voidflashRed()
{
setColor(255,0,0);
delay(200);
setColor(0,0,0);
delay(200);
}