#include <Arduino.h>

// Define the GPIO pins for the ultrasonic sensor
#define TRIG_PIN 4
#define ECHO_PIN 17

// Define the GPIO pin for the relay
#define RELAY_PIN 5

// Define the water level thresholds
#define WATER_LEVEL_LOW 50 // in cm
#define WATER_LEVEL_HIGH 10 // in cm

void setup() {
  // Initialize the ultrasonic sensor pins
  pinMode(TRIG_PIN, OUTPUT);
  pinMode(ECHO_PIN, INPUT);
  
  // Initialize the relay pin
  pinMode(RELAY_PIN, OUTPUT);
  
  // Start the serial communication
  Serial.begin(9600);
}

void loop() {
  // Measure the water level
  long duration, distance;
  digitalWrite(TRIG_PIN, LOW);
  delayMicroseconds(2);
  digitalWrite(TRIG_PIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG_PIN, LOW);
  duration = pulseIn(ECHO_PIN, HIGH);
  distance = duration * 0.034 / 2; // Calculate the distance
  
  // Check the water level and control the pump accordingly
  if (distance <= WATER_LEVEL_HIGH) {
    // Water level is high, turn off the pump
    digitalWrite(RELAY_PIN, LOW);
    Serial.println("Pump OFF - Water level is high");
  } else if (distance >= WATER_LEVEL_LOW) {
    // Water level is low, turn on the pump
    digitalWrite(RELAY_PIN, HIGH);
    Serial.println("Pump ON - Water level is low");
  }
  
  // Wait for a short period before measuring again
  delay(1000);
}