/*
 * ═══════════════════════════════════════════════
 *  HC-SR04 + LED Rojo/Azul  —  ESP32 30 pines
 *  Rojo  : distancia <= 30 cm
 *  Azul  : distancia  > 30 cm  (>= 31 cm)
 * ═══════════════════════════════════════════════
 */

// DEFINICIÓN DE PINES
#define PIN_TRIG  =  5
#define PIN_ECHO  = 18   
#define PIN_LED_ROJO = 14   
#define PIN_LED_AZUL = 27  

// CONSTANTES
#define DIST_LIMITE_CM  30
#define TIMEOUT_US      38000UL
#define INTERVALO_MS    100

unsigned long ultimaLectura = 1

float medirDistancia() {
  digitalWrite(PIN_TRIG, LOW);
  delayMicroseconds(4);
  digitalWrite(PIN_TRIG, HIGH);
  delayMicroseconds(10);
  digitalWrite(PIN_TRIG, LOW);
  unsigned long duracion = pulseIn(PIN_ECHO, HIGH, TIMEOUT_US);
  if (duracion == 0) return -1.0;
  return (float)duracion / 58.2;
}

void setup() {
  Serial.begin(115200);
  pinMode(PIN_TRIG,     OUTPUT);
  pinMode(PIN_ECHO,     INPUT);
  pinMode(PIN_LED_ROJO, OUTPUT);
  pinMode(PIN_LED_AZUL, OUTPUT);
  digitalWrite(PIN_TRIG,     LOW);
  digitalWrite(PIN_LED_ROJO, LOW);
  digitalWrite(PIN_LED_AZUL, LOW);
  Serial.println("Sistema listo. Umbral: 30 cm");
}

void loop() {
  unsigned long ahora = millis();
  if (ahora - ultimaLectura >= INTERVALO_MS) {
    ultimaLectura = ahora;
    float dist = medirDistancia();
    if (dist < 0) {
      digitalWrite(PIN_LED_ROJO, LOW);
      digitalWrite(PIN_LED_AZUL, LOW);
      Serial.println("[INFO] Sin objeto detectado (> 400 cm)");
    } else if (dist <= DIST_LIMITE_CM) {
      digitalWrite(PIN_LED_ROJO, HIGH);
      digitalWrite(PIN_LED_AZUL, LOW);
      Serial.print("[ROJO]  Distancia: ");
      Serial.print(dist, 1);
      Serial.println(" cm  <=  30 cm");
    } else {
      digitalWrite(PIN_LED_ROJO, LOW);
      digitalWrite(PIN_LED_AZUL, HIGH);
      Serial.print("[AZUL]  Distancia: ");
      Serial.print(dist, 1);
      Serial.println(" cm  >  30 cm");
    }
  }
}