//Slide switch closed is garage doors closed and loop closed; slide switch open is loop open;
//Doors open relay energizes and garage loop shunted 
//1st LED indicates module is in standby mode; garage loop will trigger alarm if either or both doors opened.
//2nd LED indicates garage loop is shunted - Locked out
//3rd LED indicates shunt relay is in delay mode

int relay = 2; //garage loop shunt relay 
int button = 3; //activate module; pin 3 is pulled up  with 1k resistor.
int drsense = 4; //simulates garage loop opening and closing. Actual loop leads connect to pin 4 and ground.
int ledLO = 6; //LOCKOUT MODE - garage loop will be shunted even if doors are open; allows unlimited time to exit and secure 
//garage doors.
int ledD = 7;  //DELAY MODE - the garage loop will be shunted and for the set time, then the garage door loop will be enabled.
int ledN = 8;  //NORMAL/STANDBY MODE
int relayDr = 9; //When doors closed relay is OFF and alarm loop is closed via NC and COM contacts; when doors open, relay is ON 
//and alarm loop is opened.
unsigned long prevTime = millis();

void setup() {
  
pinMode(relay, OUTPUT);
pinMode(button, INPUT);
pinMode(drsense, INPUT);
pinMode(ledLO, OUTPUT);
pinMode(ledD, OUTPUT);
pinMode(ledN, OUTPUT);
pinMode(relayDr, OUTPUT);
}

void loop() {
  unsigned long currentTime = millis();

  //If shunt relay is off, energize door relay when door loop is open
  if(digitalRead(relay) == LOW) {if(digitalRead(drsense) != LOW) {digitalWrite(relayDr, HIGH);} else {digitalWrite(relayDr, LOW);}}

//If shunt relay is off, ledN is ON
if (digitalRead(relay) == LOW) {digitalWrite(ledN, HIGH);}
else {digitalWrite(ledN, LOW);}

//Press button, energize shunt relay, start timer
   if(digitalRead(button) == LOW) {digitalWrite(relay, HIGH);prevTime = currentTime;digitalWrite(ledD, HIGH);}

//If button pressed while doors are open, then door open relay is turned OFF causing the alarm loop to be closed. Otherwise, when
// the shunt relay is turned OFF after the timed delay there might be a false alarm.
   if(digitalRead(button) == LOW && digitalRead(drsense) != LOW) {digitalWrite(relayDr, LOW);}
 
//If shunt relay is ON and garage loop is open, reset timer, ledLO ON, ledD, OFF; if not, ledLO OFF
if (digitalRead(relay) == HIGH && digitalRead(drsense) != LOW) {prevTime = currentTime;digitalWrite(ledLO, HIGH);digitalWrite(ledD, LOW);}  
else {digitalWrite(ledLO, LOW);} //if shunt relay (relay) is energized and door loop is open then, reset timer, turn off ledLO

//If shunt relay is ON and garage loop is closed (doors closed) ledD ON and ledLO OFF
if (digitalRead(relay) == HIGH && digitalRead(drsense) == LOW) {digitalWrite(ledD, HIGH);digitalWrite(ledLO, LOW);}

 //If shunt relay is ON and if timer has timed out, reset timer, turn OFF shunt relay, ledD OFF
 if(digitalRead(relay) == HIGH) {if (currentTime - prevTime >8000) {prevTime = currentTime;digitalWrite(relay, LOW);digitalWrite(ledD, LOW);}}

}
//The shunt relay NO and COM terminals are conntected to the alarm delay loop. The garage door loop is connected to pin 4 and ground.