Another Arduino Laser Tripwire

Step 4 The Code

Upload the following sketch but adjust the value in the "if" statement to suit your photocell. Pick a number a bit above the ambient light number. This may need tweaking later, or, just pull a curtain or shrpud the photocell to lower the ambient light in the room.

/*

• Jonathan Robson Feb 09.
• Laser tripwire activates a buzzer. adapted from
• http://www.instructables.com/id/Arduino_Laser_Tripwire/

*/

int buzzPin = 11; // buzzer connected to digital pin 11

void setup() {
pinMode(buzzPin, OUTPUT); // sets the digital pin as output
}

void loop(){
if(analogRead(0) < 850){ // this number depends on calibration of the photocell
digitalWrite(buzzPin, HIGH); // turns buzzer on
delay(1000); // waits for 1 second
digitalWrite(buzzPin, LOW); // turns buzzer off

} else{
digitalWrite(buzzPin, LOW);
}
}