Arduino Traffic Light Crossing Controller

main.c

#include <LiquidCrystal_I2C.h>
#include <math.h>

LiquidCrystal_I2C lcd(0x27, 16, 2);

const float warningTime = 1000;
const float crossingTime = 5000;

float requestedCrossingTime = 0;

enum LIGHT {
  RED = 4,
  YELLOW = 8,
  GREEN = 12,
};

void DISP_LIGHT(int light) {
  digitalWrite(RED, LOW);
  digitalWrite(YELLOW, LOW);
  digitalWrite(GREEN, LOW);
  digitalWrite(light, HIGH);
}

float lastUpdTime = 0;
const float updLimit = 1000/3;

int DISP_FPLIM() {
  if (millis() - lastUpdTime <= updLimit) {
    return 0;
  }
  lastUpdTime = millis();
  return 1;
}

void DISP_DNC() {
  if (!DISP_FPLIM()) return;
  lcd.clear();
  lcd.setCursor(0,0);
  lcd.print("Do not cross");
}

void DISP_CROSS(int timeLeft) {
  if (!DISP_FPLIM()) return;
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Cross Now: " + String(timeLeft / 1000));
}

void setup() {
  lcd.init();
  lcd.backlight();
  pinMode(3, INPUT);
  pinMode(RED, OUTPUT); // RED
  pinMode(YELLOW, OUTPUT); // YELLOW
  pinMode(GREEN, OUTPUT); // GREEN
  Serial.begin(9600);
}



void loop() {
  int requestingCrossing = digitalRead(3);
  Serial.println(requestingCrossing);

  if (!requestingCrossing && requestedCrossingTime == 0) {
    DISP_DNC();
    DISP_LIGHT(GREEN);
  }

  if (requestingCrossing == 0 || requestedCrossingTime != 0) {
    if (requestedCrossingTime == 0) return;

    float deltaTime = millis() - requestedCrossingTime;
    if (deltaTime < warningTime) {
      DISP_DNC();
      DISP_LIGHT(YELLOW);
    } else if ((deltaTime - warningTime) < crossingTime) {
      DISP_CROSS(crossingTime - (deltaTime - warningTime));
      DISP_LIGHT(RED);
    } else if (deltaTime >= warningTime + crossingTime) {
      DISP_DNC();
      DISP_LIGHT(GREEN);
      requestedCrossingTime = 0;
    }
  }

  if (requestingCrossing && requestedCrossingTime == 0) {
    requestedCrossingTime = millis();
  }
}