semaphore_algorithm_with_pedestrian_led.ino

enum SemaphoreState { GREEN, YELLOW, RED };
enum PedestrianState { IDLE, REQUESTED, CROSSING };

// first semaphore
const int LED_SM1_RED = 4;
const int LED_SM1_YELLOW = 3;
const int LED_SM1_GREEN = 12;

// second semaphore
const int LED_SM2_RED = 7;
const int LED_SM2_YELLOW = 6;
const int LED_SM2_GREEN = 5;

bool firstSemaphoreRunning = true;

SemaphoreState semaphoreState = RED;
unsigned long ledTimer = 0;
int ledIntervals[3] = {500, 3500, 1500};

const int PEDESTRIAN_RED_LED = 8;
const int PEDESTRIAN_GREEN_LED = 4;

const int PUSHBUTTON = 2;

PedestrianState pedestrianState = IDLE;
const int pedestrianLedInterval = 5000;
unsigned long pestredianLedTimer = 0;

const int blinkPedestrianLedInterval = 500;
unsigned long blinkPedestrianLedTimer = 0;

void setup() {
  Serial.begin(9600);

  pinMode(LED_SM1_RED, OUTPUT);
  pinMode(LED_SM1_YELLOW, OUTPUT);
  pinMode(LED_SM1_GREEN, OUTPUT);
  pinMode(LED_SM2_RED, OUTPUT);
  pinMode(LED_SM2_YELLOW, OUTPUT);
  pinMode(LED_SM2_GREEN, OUTPUT);
  pinMode(PEDESTRIAN_RED_LED, OUTPUT);
  pinMode(PEDESTRIAN_GREEN_LED, OUTPUT);
  pinMode(PUSHBUTTON, INPUT_PULLUP);

  digitalWrite(2, HIGH);
  digitalWrite(LED_SM1_GREEN, HIGH);
  digitalWrite(LED_SM2_RED, HIGH);
  digitalWrite(PEDESTRIAN_RED_LED, HIGH);
}

void loop1() {
  digitalWrite(LED_SM1_GREEN, HIGH);
  // digitalWrite(LED_SM1_GREEN, HIGH);
}

void loop() {
  switch (pedestrianState) {
    case IDLE:
      runCurrentSemaphore();
      break;
    case REQUESTED:
      if (semaphoreState == RED) {
        pedestrianState = CROSSING;
        disableSemaphores();
        digitalWrite(PEDESTRIAN_RED_LED, LOW);
        digitalWrite(PEDESTRIAN_GREEN_LED, HIGH);
        pestredianLedTimer = millis();
      } else {
        blinkPedestrianLed();
        runCurrentSemaphore();
      }
      break;
    case CROSSING:
      if (millis() - pestredianLedTimer >= pedestrianLedInterval) {
        pedestrianState = IDLE;
        digitalWrite(PEDESTRIAN_RED_LED, HIGH);
        digitalWrite(PEDESTRIAN_GREEN_LED, LOW);
      }
      break;
  }
  if (buttonPressed()) {
    pedestrianState = REQUESTED;
  }
}

void runCurrentSemaphore() {
  int pinGreen = firstSemaphoreRunning ? LED_SM1_GREEN : LED_SM2_GREEN;
  int pinYellow = firstSemaphoreRunning ? LED_SM1_YELLOW : LED_SM2_YELLOW;
  int pinRed = firstSemaphoreRunning ? LED_SM1_RED : LED_SM2_RED;

  unsigned long now = millis();
  unsigned long diff = now - ledTimer;

  if (diff >= ledIntervals[0] && semaphoreState == RED) {
    ledTimer = now;
    semaphoreState = GREEN;
    digitalWrite(pinRed, LOW);
    digitalWrite(pinGreen, HIGH);
    int x = firstSemaphoreRunning ? 1 : 2;
    Serial.print("ENABLE PIN GREEN FOR ");
    Serial.println(x);
  } else if (diff >= ledIntervals[1] && semaphoreState == GREEN) {
    ledTimer = now;
    semaphoreState = YELLOW;
    digitalWrite(pinGreen, LOW);
    digitalWrite(pinYellow, HIGH);
   int x = firstSemaphoreRunning ? 1 : 2;
    Serial.print("ENABLE PIN YELLOW FOR ");
    Serial.println(x);
  } else if (diff >= ledIntervals[2] && semaphoreState == YELLOW) {
    ledTimer = now;
    semaphoreState = RED;
    digitalWrite(pinYellow, LOW);
    digitalWrite(pinRed, HIGH);
   int x = firstSemaphoreRunning ? 1 : 2;
    Serial.print("ENABLE PIN RED FOR ");
    Serial.println(x);
    firstSemaphoreRunning = !firstSemaphoreRunning;
  }
}

void disableSemaphores() {
    digitalWrite(LED_SM1_RED, HIGH);
    digitalWrite(LED_SM1_YELLOW, LOW);
    digitalWrite(LED_SM1_GREEN, LOW);
    digitalWrite(LED_SM2_RED, HIGH);
    digitalWrite(LED_SM2_YELLOW, LOW);
    digitalWrite(LED_SM2_GREEN, LOW);
}

void blinkPedestrianLed() {
  int walkLedState = digitalRead(PEDESTRIAN_RED_LED);
  unsigned long now = millis();
  if (now - pestredianLedTimer >= blinkPedestrianLedInterval) {
    pestredianLedTimer = now;
    int state = (digitalRead(PEDESTRIAN_RED_LED) == LOW) ? HIGH : LOW;
    digitalWrite(PEDESTRIAN_RED_LED, state);
  }
}

bool buttonPressed() {
  return pedestrianState == IDLE && digitalRead(PUSHBUTTON) == LOW && semaphoreState != RED;
}