Laser Security Alarm System Problem

[nicholas_1]

Hi,
I'm doing my assignment for school and I've came across this problem in my code. When the laser is interrupted the alarm goes off like it should. The problem with my code is when I try to reset it with a button. The purpose of the button is to turn the laser back to high which therefore, turns the alarm off. Practically if the alarm is on the laser is off and when the alarm is off the laser is on. The button works as intended but only when its being held down. When I let go of it, the alarm restarts. I want the alarm to turn off and the laser to go back to high when the button is pressed. Thanks.
This project uses a laser, photoresistor/ldr, a button and a buzzer.

int laserPin = 4;
int photoresistorPin = A1;
int buttonPin = 5;
int buzzerPin = 3;

int threshold = 12;

void setup() {
  pinMode(laserPin, OUTPUT);
  pinMode(buttonPin, INPUT_PULLUP);
  Serial.begin(9600);
}

bool alarm = false;

void loop() {
  if (alarm == false) {
    delay(1000);
    digitalWrite(laserPin, HIGH);
    delay(10);
    unsigned long current = millis();
    while (millis() - current < 1000) {
      int Value = analogRead(laserPin);
      if (Value > threshold) {
        alarm = true;
        break;
      }
      delay(10);
    }
    digitalWrite(laserPin, LOW);
  } else {
    tone(buzzerPin, 440);
    if (!digitalRead(buttonPin)) {
      alarm = false;
      noTone(buzzerPin);
    }
    delay(10);
  }
}

[J-M-L]

what's going on with all the delays?

It's a simple state machine using your boolean to represent the state

if the alarm is off, you need to check if the laser beam is interrupted and in that case trigger the alarm state
if the alarm is on, you need to check if the button is being pressed and in that case restore the watch state

const byte laserPin = 4;
const byte photoresistorPin = A1;
const byte buttonPin = 5;
const byte buzzerPin = 3;
const int threshold = 12;
bool alarmIsOn = false;

void setup() {
  pinMode(buzzerPin, OUTPUT);
  pinMode(laserPin, OUTPUT);
  pinMode(buttonPin, INPUT_PULLUP);
  digitalWrite(laserPin, HIGH);
}


void alarmIsOn() {
  if (alarm) {
    // alarm is sounding/on, check if the stop button is pressed 
    if (digitalRead(buttonPin) == LOW) {
      alarm = false;
      digitalWrite(laserPin, HIGH);
      noTone(buzzerPin);
    }
  } else {
    // alarm is off, check if the laser beam is interrupted
    if (analogRead(photoresistorPin) > threshold) {
      alarm = true;
      digitalWrite(laserPin, LOW);
      tone(buzzerPin, 440);
    }
  }
}

[jim-p]

@nicholas_1

Should
int Value = analogRead(laserPin);

be?

int Value = analogRead(photoresistorPin);

[J-M-L]

good catch

[nicholas_1]

Hi, when verifying this code it comes up with an error.
sketch_nov09d:16: error: 'void alarmIsOn()' redeclared as different kind of symbol

void alarmIsOn() {

            ^

note: previous declaration 'bool alarmIsOn'

bool alarmIsOn = false;

  ^

In function 'void alarmIsOn()':

error: 'void alarmIsOn()' redeclared as different kind of symbol

void alarmIsOn() {

            ^

note: previous declaration 'bool alarmIsOn'

bool alarmIsOn = false;

  ^

exit status 1
'void alarmIsOn()' redeclared as different kind of symbol

I'm not quite sure how to fix this issue as it says 'alarmIsOn' is declared as a different kind of symbol.

[J-M-L]

I typed it here in the forum from my iPhone and gave wrongly the same name to the function and the bookl variable, alarmIsOn

Change the function name into loop.. (the void loop() is missing )

const byte laserPin = 4;
const byte photoresistorPin = A1;
const byte buttonPin = 5;
const byte buzzerPin = 3;
const int threshold = 12;
bool alarmIsOn = false;

void setup() {
  pinMode(buzzerPin, OUTPUT);
  pinMode(laserPin, OUTPUT);
  pinMode(buttonPin, INPUT_PULLUP);
  digitalWrite(laserPin, HIGH);
}


void loop() {
  if (alarm) {
    // alarm is sounding/on, check if the stop button is pressed 
    if (digitalRead(buttonPin) == LOW) {
      alarm = false;
      digitalWrite(laserPin, HIGH);
      noTone(buzzerPin);
    }
  } else {
    // alarm is off, check if the laser beam is interrupted
    if (analogRead(photoresistorPin) > threshold) {
      alarm = true;
      digitalWrite(laserPin, LOW);
      tone(buzzerPin, 440);
    }
  }
}