// Pin Definitions
#define TRIG_PIN_1 5
#define ECHO_PIN_1 4
#define TRIG_PIN_2 8
#define ECHO_PIN_2 9
#define LED_A 10
#define LED_B 11
#define LED_C 12
#define LED_D 13
#define LED_RED 2

// Constants
const float SPEED_OF_SOUND = 0.034; // Speed of sound in cm per microsecond
const int LED_THRESHOLD_A = 5;       // Distance threshold for LED A
const int LED_THRESHOLD_B = 7;       // Distance threshold for LED B
const int LED_THRESHOLD_C = 10;      // Distance threshold for LED C
const int LED_THRESHOLD_D = 15;      // Distance threshold for LED D
const int LED_THRESHOLD_RED = 20;    // Distance threshold for LED RED

// Function prototypes
float measureDistance(int trigPin, int echoPin);

void setup() {
  Serial.begin(9600);

  // Ultrasonic Sensor Setup
  pinMode(TRIG_PIN_1, OUTPUT);
  pinMode(ECHO_PIN_1, INPUT);
  pinMode(TRIG_PIN_2, OUTPUT);
  pinMode(ECHO_PIN_2, INPUT);

  // LED Setup
  pinMode(LED_A, OUTPUT);
  pinMode(LED_B, OUTPUT);
  pinMode(LED_C, OUTPUT);
  pinMode(LED_D, OUTPUT);
  pinMode(LED_RED, OUTPUT);
}

void loop() {
  // Measure distances from both sensors
  float distance1 = measureDistance(TRIG_PIN_1, ECHO_PIN_1);
  float distance2 = measureDistance(TRIG_PIN_2, ECHO_PIN_2);

  // Control LEDs based on sensor readings
  digitalWrite(LED_A, (distance1 > LED_THRESHOLD_A && distance1 < LED_THRESHOLD_B) ? HIGH : LOW);
  digitalWrite(LED_B, (distance2 > LED_THRESHOLD_B && distance2 < LED_THRESHOLD_C) ? HIGH : LOW);
  digitalWrite(LED_C, (distance1 > LED_THRESHOLD_C && distance1 < LED_THRESHOLD_D) ? HIGH : LOW);
  digitalWrite(LED_D, (distance2 > LED_THRESHOLD_D && distance2 < LED_THRESHOLD_RED) ? HIGH : LOW);
  digitalWrite(LED_RED, (distance1 > LED_THRESHOLD_RED || distance2 > LED_THRESHOLD_RED) ? HIGH : LOW);

  // Delay before next iteration
  delay(500);
}

// Function to measure distance using ultrasonic sensor
float measureDistance(int trigPin, int echoPin) {
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);
  return pulseIn(echoPin, HIGH) * SPEED_OF_SOUND / 2.0;
}