How to add the Interrupt(); function to arduino code

Question

For a small school project I am building a simulation of a traffic light system, based on three directions. What makes the system special is it can detect vehicles waiting in front of the traffic light. When a vehicle is detected, the given direction will get a green light. To do so I make use of a Hall Effect sensor. Right now I am stuck on the following problem; the Arduino stops detecting the state of the sensor while giving a certain direction a green light. I already have read about the Interrupt() function to do certain tasks simultaneously but didn't manage to implement it in my code.

Hope you guys know a way to do so!

int sensorPin3 = 2;
int sensorPin2 = 3;
int sensorPin1 = 4;
int g1 = 11;
int y1 = 12;
int r1 = 13;
int g2 = 8;
int y2 = 9;
int r2 = 10;
int g3 = 5;
int y3 = 6;
int r3 = 7;
int counter = 0;
boolean sensorState1 = false;
boolean sensorState2 = false;
boolean sensorState3 = false;

void setup() 
{
  // setup serial - diagnostics - port
  Serial.begin(9600);
  pinMode(sensorPin1, INPUT);
  pinMode(sensorPin2, INPUT);
  pinMode(sensorPin3, INPUT);
  digitalWrite(sensorPin1, HIGH);
  digitalWrite(sensorPin2, HIGH);
  digitalWrite(sensorPin3, HIGH);
  pinMode(g1, OUTPUT);
  pinMode(y1, OUTPUT);
  pinMode(r1, OUTPUT);
  pinMode(g2, OUTPUT);
  pinMode(y2, OUTPUT);
  pinMode(r2, OUTPUT);
  pinMode(g3, OUTPUT);
  pinMode(y3, OUTPUT);
  pinMode(r3, OUTPUT);
}

void loop() 
{
  digitalWrite (r1, HIGH);
  digitalWrite (r2, HIGH);
  digitalWrite (r3, HIGH);
  if(magnetPresent(sensorPin1) && !sensorState1)
  {
    sensorState1 = true;
  }
  else if(!magnetPresent(sensorPin1) && sensorState1)
  {
    if(sensorState1 = false);
    Serial.println("detect1"); 
    richting1();   
  }
  if(magnetPresent(sensorPin2) && !sensorState2)
  {
    sensorState2 = true;
  }
  else if(!magnetPresent(sensorPin2) && sensorState2)
  {
    if (sensorState2 = false);
    Serial.println("detect2");
    richting2();
  }
  if(magnetPresent(sensorPin3) && !sensorState3)
  {
    sensorState3 = true;
  }
  else if(!magnetPresent(sensorPin3) && sensorState3)
  {
    if (sensorState3 = false);
    Serial.println("detect3");
    richting3();
  }
}

void printMessage(String message){
  counter++;

  Serial.print(counter);
  Serial.print(" ");
  Serial.println(message);
}

boolean magnetPresent(int pin){
  return digitalRead(pin) == LOW;
}

void richting1()
{
  digitalWrite (r1, HIGH);
  digitalWrite (r2, HIGH);
  digitalWrite (r3, HIGH);
  delay(2000);
  digitalWrite (r1, LOW);
  digitalWrite (r2, HIGH);
  digitalWrite (r3, HIGH);
  digitalWrite (g1, HIGH);
  delay(10000);
  digitalWrite (y1, HIGH);
  digitalWrite (r2, HIGH);
  digitalWrite (r3, HIGH);
  digitalWrite (g1, LOW);
  delay(2000);
  digitalWrite (y1, LOW);
  digitalWrite (r1, HIGH);
}

void richting2()
{
  digitalWrite (r1, HIGH);
  digitalWrite (r2, HIGH);
  digitalWrite (r3, HIGH);
  delay(2000);
  digitalWrite (r2, LOW); 
  digitalWrite (r1, HIGH);
  digitalWrite (r3, HIGH);
  digitalWrite (g2, HIGH);
  delay(10000);
  digitalWrite (y2, HIGH);
  digitalWrite (r1, HIGH);
  digitalWrite (r3, HIGH);
  digitalWrite (g2, LOW);
  delay(2000);
  digitalWrite (y2, LOW);
  digitalWrite (r2, HIGH);  
}

void richting3()
{
  digitalWrite (r1, HIGH);
  digitalWrite (r2, HIGH);
  digitalWrite (r3, HIGH);
  delay(2000);
  digitalWrite (r3, LOW);
  digitalWrite (y3, LOW);
  digitalWrite (r1, HIGH);
  digitalWrite (r2, HIGH);
  digitalWrite (g3, HIGH);
  delay(10000);
  digitalWrite (y3, HIGH);
  digitalWrite (r1, HIGH);
  digitalWrite (r2, HIGH);
  digitalWrite (g3, LOW);
  delay(2000);
  digitalWrite (y3, LOW);
  digitalWrite (r3, HIGH);
}

Answer 1

@NickGammon made a great posts about interrupts and how to use them. It is more then complete so here is the link:

https://arduino.stackexchange.com/questions/30968/how-do-interrupts-work-on-the-arduino-uno-and-similar-boards

---

This is just a little opinion, but for traffic light codes, I found it a little simpler to make something like a custom delay. Take a look at this code and you'll hopefully understand it. Again, this was one of my school project in which I've used a template so you might see some useless crap in it!

/*  This program acts like a pedestrian light. If the button is pressed, a light will turn on for a certain moment to let the person pass.

    By   : Dat HA
    Date : 16/09/27
*/

//****************************** VARIABLES ******************************

const int leds[4][12] = //declaring leds - RED, YELLOW, GREEN
{
  //R,Y,G,
  {5, 6, 7},   //north
  {8, 9, 10},  //east
  {11, 12, 13}, //south
  {2, 3, 4}    //west
};


/* Sensors: sensorNumber - itemInArray - sensorDescription - pinDescription

    1 - 0 - pushbutton
    2 - 1 - photocell
    3 - 2 - potentiometer
    4 - 3 - distance      - distanceEcho
    5 - 4 - distance      - distanceTrigger
    6 - 5 - pushbutton (2)
    7 - 6 - servo
*/
const int sensors[]   = {A2, A7, A6, A4, A5, A3, A0}; //pin for each sensor

//******************************   SETUP   ******************************


const int analogPins[6] = {A0, A1, A2, A3, A4, A5}; //for quick pinMode, distanceTrigger we be redeclared as an output is it is an analog input pin

void setup() {

  for (int i = 2; i < 14; i++)     //declaring digital pins as output for leds
  {
    pinMode(i, OUTPUT);
  }

  for (int i = 0; i < 6; i++)      //declaring analog inputs
  {
    pinMode(analogPins[i], INPUT);
  }

  pinMode(sensors[4], OUTPUT);     //declaring trigger pin as an output

}

//****************************** MAIN LOOP ******************************
int green = 5000;
int yellow = 3000;
int aa = 0;


void loop() {

  //north, south
  digitalWrite(leds[0][0], LOW); //red light off
  digitalWrite(leds[2][0], LOW);

  digitalWrite(leds[0][2], HIGH); //green light on
  digitalWrite(leds[2][2], HIGH);

  wait(green);

  digitalWrite(leds[0][2], LOW); //green light off
  digitalWrite(leds[2][2], LOW);

  digitalWrite(leds[0][1], HIGH); //yellow light on
  digitalWrite(leds[2][1], HIGH);

  wait(yellow);

  digitalWrite(leds[0][1], LOW); //yellow light off
  digitalWrite(leds[2][1], LOW);

  digitalWrite(leds[0][0], HIGH); //red light on
  digitalWrite(leds[2][0], HIGH);

  delay(100);

  if (aa == 1)
  {
    flash();
  }

  //*************** SWITCHING SIDES ***************

  digitalWrite(leds[1][0], LOW); //red light off
  digitalWrite(leds[3][0], LOW);

  digitalWrite(leds[1][2], HIGH); //green light on
  digitalWrite(leds[3][2], HIGH);

  wait(green);

  digitalWrite(leds[1][2], LOW); //green light off
  digitalWrite(leds[3][2], LOW);

  digitalWrite(leds[1][1], HIGH); //yellow light on
  digitalWrite(leds[3][1], HIGH);

  wait(yellow);

  digitalWrite(leds[1][1], LOW); //yellow light off
  digitalWrite(leds[3][1], LOW);

  digitalWrite(leds[1][0], HIGH); //red light on
  digitalWrite(leds[3][0], HIGH);

  delay(100);

  if (aa == 1)
  {
    flash();
  }
}

//****************************** FUNCTIONS ******************************
/* Usable functions list:

   LEDS functions - do something to the leds

   ledClear() turn all leds off

   ledRedOn()  turn all red leds on
   ledYelOn()  turn all yellow leds on
   ledGreOn()  turn all green leds on

   SENSORS functions - they will return the apropriate value

   pushButton()     values: 0,1
   photocell()      values: 0-1023
   potentiometer()  values: 0-1023
   distance()       values: 0-200
*/

void ledClear() //turn off all leds
{
  for (int i = 2; i < 14; i++)
  {
    digitalWrite(i, LOW); //turning leds off
  }
}

void ledRedOn()
{
  for (int i = 0; i < 4; i++)
  {
    digitalWrite(leds[i][0], HIGH); //turning red leds on
  }
}

void ledRedOff()
{
  for (int i = 0; i < 4; i++)
  {
    digitalWrite(leds[i][0], LOW); //turning red leds on
  }
}

void ledYelOn()
{
  for (int i = 0; i < 4; i++)
  {
    digitalWrite(leds[i][1], HIGH); //turning yellow leds on
  }
}

void ledGreOn()
{
  for (int i = 0; i < 4; i++)
  {
    digitalWrite(leds[i][2], HIGH); //turning green leds on
  }
}

int pushButton()    // sensor 1
{
  int x = digitalRead(sensors[0]);
  return x; //returning digital value of pushbutton which is either 0 or 1
}

void flash()  //flash the red led
{
  for (int i = 0; i < 12; i++)
  {
    ledGreOn();
    ledRedOn(); //on
    delay(200); //wait
    ledRedOff(); //off
    delay(200); //wait
  }
  ledClear();
  aa = 0;
}

int wait(int x) //see if the wire is disconnected and if so, flash the red led
{
  int i = 0;
  unsigned long currentMillis = millis(); //current time
  while (millis() - currentMillis <= x) //delay
  {
    if (digitalRead(A2) == HIGH) //if wire disconnected
    {
      aa = 1;
    }
  }
}