#define TRIG 5     // Ultrasonic TRIG pin connected to GPIO5
#define ECHO 18    // Ultrasonic ECHO pin connected to GPIO18
#define LED  2     // LED connected to GPIO2 (with resistor)

long duration;
int distance;

void setup() {
  pinMode(TRIG, OUTPUT);
  pinMode(ECHO, INPUT);
  pinMode(LED, OUTPUT);
  Serial.begin(200);  // Serial monitor for distance output
}

void loop() {
  // Send ultrasonic pulse
  digitalWrite(TRIG, LOW);
  delayMicroseconds(2);
  digitalWrite(TRIG, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG, LOW);

  // Measure echo time
  duration = pulseIn(ECHO, HIGH);

  // Convert to distance in cm
  distance = duration * 0.034 / 2;

  // Print distance
  Serial.print("Distance: ");
  Serial.print(distance);
  Serial.println(" cm");

  // Smart Jar Logic
  if (distance < 10) {  // If object is closer than 10 cm
    digitalWrite(LED, HIGH); 
    Serial.println("Jar is FULL!");
  } else {
    digitalWrite(LED, LOW); 
    Serial.println("Jar has space.");
  }

  delay(1000); // Wait 1 second
}