traffic.ino

// https://tronixstuff.com/2025/04/15/project-arduino-controlled-traffic-lights/
//
// define the I/O pins that are used on the Arduino
// ... the buttons
#define westButton 5
#define eastButton 12

// the LEDs on the traffic light modules
#define westRed 4
#define westYellow 3
#define westGreen 2

#define eastRed 11
#define eastYellow 10
#define eastGreen 9

#define yellowBlinkTime 500 // 0.5 seconds for yellow light blink

boolean trafficWest = true; // west = true, east = false
int flowTime = 5000; // amount of time to let traffic flow
int changeDelay = 2000; // amount of time between color changes

void setup()
{
  // this code runs when the Arduino first powers-up
  // or after a reset
  
  // setup digital I/O pins
  // buttons are INPUTs
  pinMode(westButton, INPUT);
  pinMode(eastButton, INPUT);
  // LEDs are OUTPUTs
  pinMode(westRed, OUTPUT);
  pinMode(westYellow, OUTPUT);
  pinMode(westGreen, OUTPUT);
  pinMode(eastRed, OUTPUT);
  pinMode(eastYellow, OUTPUT);
  pinMode(eastGreen, OUTPUT);
  
  // set initial state for lights - west side is green first
  digitalWrite(westRed, LOW);
  digitalWrite(westYellow, LOW);
  digitalWrite(westGreen, HIGH);
  digitalWrite(eastRed, HIGH);
  digitalWrite(eastYellow, LOW);
  digitalWrite(eastGreen, LOW);
}

void loop()
// this code runs continuously until power-off or a reset
{
  if ( digitalRead(westButton) == HIGH ) 
  // request west to east traffic flow
  {
    if ( trafficWest != true )
      // only continue if traffic flowing in the opposite (east) direction
    {
      trafficWest = true; // change traffic flow flag to west>east
      delay(flowTime); // give time for traffic to clear the bridge
      digitalWrite(eastGreen, LOW); // change east-facing lights from green...
      // to yellow to red
      digitalWrite(eastYellow, HIGH);
      delay(changeDelay);
      digitalWrite(eastYellow, LOW);
      digitalWrite(eastRed, HIGH);
      delay(changeDelay);
      for ( int a = 0; a < 5; a++ ) // blink yellow light
      {
        digitalWrite(westYellow, LOW);
        delay(yellowBlinkTime);
        digitalWrite(westYellow, HIGH);
        delay(yellowBlinkTime);
      }
      digitalWrite(westYellow, LOW);
      digitalWrite(westRed, LOW); // change west-facing lights from red to green
      digitalWrite(westGreen, HIGH);
    }
  }
  if ( digitalRead(eastButton) == HIGH ) // request east to west traffic flow
  {
    if ( trafficWest == true )
      // only continue if traffic flow is in the opposite (west) direction
    {
      trafficWest = false; // change traffic flow flag to east>west
      delay(flowTime); // give time for traffic to clear the bridge
      digitalWrite(westGreen, LOW);
      // change west lights from green to yellow to red
      digitalWrite(westYellow, HIGH);
      delay(changeDelay);
      digitalWrite(westYellow, LOW);
      digitalWrite(westRed, HIGH);
      delay(changeDelay);
      for ( int a = 0 ; a < 5 ; a++ ) // blink yellow light
      {
        digitalWrite(eastYellow, LOW);
        delay(yellowBlinkTime);
        digitalWrite(eastYellow, HIGH);
        delay(yellowBlinkTime);
      }
      digitalWrite(eastYellow, LOW);
      digitalWrite(eastRed, LOW); // change east-facing lights from red to green
      digitalWrite(eastGreen, HIGH);
    }
  }
}