Tilt activated alarm

gistfile1.txt

/*
 Fake Hide-A-Key Rock Intruder Alarm
 written for an Arduino Uno
 by Sarah Pavis
 */

// include the LCD screen library code
#include <LiquidCrystal.h>

// initialize the library with the numbers of the interface pins
LiquidCrystal lcd(12, 11, 5, 4, 3, 2);

// fix the pin numbers for the tilt switch pin and reset button 
const int tiltPin = 6;
const int alarmPin = 7;

// variables to hold the states of the tiltPin
int tiltState = 0;
int prevTiltState = 0;

//  variable for the alarm reset buttoon
int alarmButton = 0;

// time check variables for determining LED blink
unsigned long currentTime;
long prevTime = 0;
long blinkRate = 200;

// the pin locations of the LEDs
// could be called out below but it's easier to change the program later on 
// if the locations are kept as variables up here
int upperLight = 9;
int lowerLight = 8;

// variables to hold the high or low LED states
int upperLightState;
int lowerLightState;

// a variable to hold the time the alarm was first activated
long alarmTime;

// 30 sec alarm duration after which it resets to standby mode
long alarmLength = 30000;

// a flag variable to be activated the first time the tilt switch changes state
boolean intruder = false;



void setup() {
  // open the serial port for debugging and alarm logs
  Serial.begin(9600);
  // set the LED pins as output
  pinMode(lowerLight, OUTPUT);
  pinMode(upperLight, OUTPUT);
  // set the tilt switch and button pins as an input
  pinMode(tiltPin, INPUT);
  pinMode(alarmPin, INPUT);
  // clears anything previously on the LCD
  lcd.clear();
  // establishes the LCD screen as 16 columns by 2 rows
  lcd.begin(16, 2);
  // initial screen before thee alarm is activated
  // ideally the LCD would be off completely 
  // but it's useful to have a neutral message here 
  // for clarity and debugging
  lcd.print("Alarm is in");
  lcd.setCursor(0, 1);
  lcd.print("standby mode.");
}

void loop() {  
  // checks the states of each sensor and
  // sets the values to variables
  tiltState = digitalRead(tiltPin);
  alarmButton = digitalRead(alarmPin);
  // if the device has been tilted 
  // then register that there is an intruder
  if (tiltState != prevTiltState) {
      intruder = true;
  }
  // alarm routine
  if (intruder == true) {  
      lcd.setCursor(0, 0);
      lcd.print("Intruder Alert");
      lcd.setCursor(0, 1);
      lcd.print("Alarm Activated");
      
      // get the current time and set it 
      currentTime = millis();
      // this should set the current time as the start of the alarm
      // but it resets the variable every time it loops
      // i need to refactor this so that alarmTime is constant
      alarmTime = millis();
     
     // blink the LEDs without delaying the program
      if ((currentTime - prevTime) > blinkRate) {
        if (upperLightState == HIGH) {
          lowerLightState = HIGH;
          upperLightState = LOW;
        }
        else {
          lowerLightState = LOW;
          upperLightState = HIGH;
        }
        digitalWrite(upperLight, upperLightState);
        digitalWrite(lowerLight, lowerLightState);
        prevTime = currentTime;
      }
      // if the reset button is pushed or the alarm goes off for too long
      // then reset the alarm 
      if (alarmLength <= currentTime - alarmTime || alarmButton == HIGH) {
        intruder = false; 
      }
      // alarm reset sequence
      if (intruder == false) {
          lcd.clear();
          lcd.begin(16, 2);
          lcd.print("Alarm is in");
          lcd.setCursor(0, 1);
          lcd.print("standby mode.");
          digitalWrite(upperLight, LOW);
          digitalWrite(lowerLight, LOW);
      }
  }
}