列車走行に合わせて LED信号機の現示を変更する

const int SIG_A_LED_G = 6;
const int SIG_A_LED_Y = 7;
const int SIG_A_LED_R = 8;

const int SENSOR_A_1 = 2;
const int SENSOR_A_2 = 3;
const int SENSOR_B_1 = 11;
const int SENSOR_C_1 = 12;

const int SIGNAL_STOP = 0;
const int SIGNAL_WARN = 1;
const int SIGNAL_CAUTION = 2;
const int SIGNAL_REDUCE = 3;
const int SIGNAL_CLEARD = 4;

int signalA = SIGNAL_CLEARD;
int signalB = SIGNAL_CLEARD;
int signalC = SIGNAL_CLEARD;


void setup() {
  // put your setup code here, to run once:
  pinMode(SENSOR_A_1, INPUT_PULLUP);
  pinMode(SENSOR_A_2, INPUT_PULLUP);
  pinMode(SENSOR_B_1, INPUT_PULLUP);
  pinMode(SENSOR_C_1, INPUT_PULLUP);
  pinMode(SIG_A_LED_G, OUTPUT);
  pinMode(SIG_A_LED_Y, OUTPUT);
  pinMode(SIG_A_LED_R, OUTPUT);

  digitalWrite(SIG_A_LED_G, LOW);
  digitalWrite(SIG_A_LED_Y, LOW);
  digitalWrite(SIG_A_LED_R, LOW);

  Serial.begin(9600);
  while (!Serial) {
    ;
  }
}

void loop() {
  // put your main code here, to run repeatedly:
  int sensor1, sensor2, sensorB, sensorC;
  sensor1 = digitalRead(SENSOR_A_1);
  sensor2 = digitalRead(SENSOR_A_2);
  sensorB = digitalRead(SENSOR_B_1);
  sensorC = digitalRead(SENSOR_C_1);
  Serial.print("sensor1: ");
  Serial.print(sensor1);
  Serial.print(", sensor2: ");
  Serial.print(sensor2);
  Serial.print(", sensorB: ");
  Serial.print(sensorB);
  Serial.print(", sensorC: ");
  Serial.println(sensorC);

  if (sensor1 == LOW) {
    signalA = SIGNAL_STOP;
  } else if (sensorB == LOW) {
    signalA = SIGNAL_CAUTION;
  } else if (sensorC == LOW) {
    signalA = SIGNAL_CLEARD;
  } else if (sensor2 == LOW) { //逆行
    signalA = SIGNAL_STOP;
  }

  updateSignal(signalA);
  delay(50);
}


void updateSignal(int signal) {
  int green = LOW, yellow = LOW, red = LOW;
  switch (signal) {
  case SIGNAL_STOP:
    red = HIGH;
    break;
  case SIGNAL_CAUTION:
    yellow = HIGH;
    break;
  case SIGNAL_CLEARD:
    green = HIGH;
    break;
  default:
    red = HIGH;
    yellow = HIGH;
    break;
  }
  digitalWrite(SIG_A_LED_G, green); 
  digitalWrite(SIG_A_LED_Y, yellow);
  digitalWrite(SIG_A_LED_R, red);
}