Introduction: Arduino Laser System-Tripwire Tutorial
I made it using an Arduino, a laser diode, a photocell (light dependent resistor) and a piezo buzzer.
Code :
const int PHOTOCELL_PIN = A0;
const int BUZZER_PIN = 3;
// voltage readings are in 0-1023 range
const int THRESHOLD = 500;
void setup() {
pinMode(PHOTOCELL_PIN, INPUT);
Serial.begin(9600);
}
long alarmEndTime = 0;
void loop() {
int level = analogRead(PHOTOCELL_PIN);
Serial.println(level);
long time = millis();
if (time < alarmEndTime) {
long timeLeft = alarmEndTime - time;
if (timeLeft % 1000 > 300) {
tone(BUZZER_PIN, 4000);
} else {
noTone(BUZZER_PIN);
}
} else {
noTone(BUZZER_PIN);
if (level < THRESHOLD) {
alarmEndTime = time + 3000;
}
}
}
Code :
const int PHOTOCELL_PIN = A0;
const int BUZZER_PIN = 3;
// voltage readings are in 0-1023 range
const int THRESHOLD = 500;
void setup() {
pinMode(PHOTOCELL_PIN, INPUT);
Serial.begin(9600);
}
long alarmEndTime = 0;
void loop() {
int level = analogRead(PHOTOCELL_PIN);
Serial.println(level);
long time = millis();
if (time < alarmEndTime) {
long timeLeft = alarmEndTime - time;
if (timeLeft % 1000 > 300) {
tone(BUZZER_PIN, 4000);
} else {
noTone(BUZZER_PIN);
}
} else {
noTone(BUZZER_PIN);
if (level < THRESHOLD) {
alarmEndTime = time + 3000;
}
}
}