Circuit Documentation

Summary

This circuit is designed to manage runway clearance and emergency alerts using an Arduino UNO. It includes LEDs to indicate runway status, a buzzer for emergency alerts, and an ultrasonic sensor for additional functionality. The system also includes resistors to limit current to the LEDs and a button to request runway clearance.

Component List

1. LED: Two Pin (red)

   • Description: Red LED
   • Pins: Cathode, Anode

2. LED: Two Pin (green)

   • Description: Green LED
   • Pins: Cathode, Anode

3. Resistor (200 Ohms)

   • Description: Current limiting resistor
   • Pins: Pin1, Pin2

4. Arduino UNO

   • Description: Microcontroller
   • Pins: UNUSED, IOREF, Reset, 3.3V, 5V, GND, Vin, A0, A1, A2, A3, A4, A5, SCL, SDA, AREF, D13, D12, D11, D10, D9, D8, D7, D6, D5, D4, D3, D2, D1, D0

5. Resistor (200 Ohms)

   • Description: Current limiting resistor
   • Pins: Pin1, Pin2

6. Buzzer

   • Description: Sound alert
   • Pins: Positive, Negative

7. Ultrasonic Sensor

   • Description: Distance measurement sensor
   • Pins: +VCC, Trigger, Echo, GND

Wiring Details

LED: Two Pin (red)

• Cathode: Connected to GND of Arduino UNO
• Anode: Connected to Pin2 of Resistor (200 Ohms)

LED: Two Pin (green)

• Cathode: Connected to GND of Arduino UNO
• Anode: Connected to Pin2 of Resistor (200 Ohms)

Resistor (200 Ohms)

• Pin1: Connected to D10 of Arduino UNO
• Pin2: Connected to Anode of Red LED

Arduino UNO

• D10: Connected to Pin1 of Resistor (200 Ohms)
• GND: Connected to Cathode of Red LED, Cathode of Green LED, GND of Ultrasonic Sensor, Negative of Buzzer
• D9: Connected to Pin1 of Resistor (200 Ohms)
• 5V: Connected to +VCC of Ultrasonic Sensor
• D8: Connected to Positive of Buzzer
• D4: Connected to Echo of Ultrasonic Sensor
• D3: Connected to Trigger of Ultrasonic Sensor

Resistor (200 Ohms)

• Pin1: Connected to D9 of Arduino UNO
• Pin2: Connected to Anode of Green LED

Buzzer

• Positive: Connected to D8 of Arduino UNO
• Negative: Connected to GND of Arduino UNO

Ultrasonic Sensor

• +VCC: Connected to 5V of Arduino UNO
• Trigger: Connected to D3 of Arduino UNO
• Echo: Connected to D4 of Arduino UNO
• GND: Connected to GND of Arduino UNO

Code Documentation

// Pin definitions
const int greenLED = 9;        // Runway clear LED
const int redLED = 10;         // Emergency LED
const int requestButton = 2;   // Button to request clearance
const int buzzer = 8;          // Buzzer for emergency alert

// Variables to keep track of states
bool runwayClear = true;       // Indicates if runway is available
bool emergencyActive = false;  // Indicates an emergency
unsigned long lastEmergencyTime = 0; // Last time an emergency occurred
unsigned long nextEmergencyDelay = 20000; // Minimum 20 seconds

void setup() {
  // Set up pin modes
  pinMode(greenLED, OUTPUT);
  pinMode(redLED, OUTPUT);
  pinMode(buzzer, OUTPUT);
  pinMode(requestButton, INPUT_PULLUP); // Using INPUT_PULLUP for stable button reading

  // Initial conditions - all indicators off
  digitalWrite(greenLED, LOW);  // Green LED off
  digitalWrite(redLED, LOW);    // Red LED off
  digitalWrite(buzzer, LOW);    // Buzzer off

  Serial.begin(9600);           // Begin serial communication for debugging

  // Seed the random number generator
  randomSeed(analogRead(A0));

  // Schedule the first random emergency
  scheduleNextEmergency();
}

void loop() {
  // Check button press
  if (digitalRead(requestButton) == LOW) {
    delay(5); // Debounce delay
    if (digitalRead(requestButton) == LOW) { // Confirm button press
      handleRunwayRequest();
    }
  }

  // Handle emergency timing
  if (millis() - lastEmergencyTime > nextEmergencyDelay) {
    activateEmergency();
    scheduleNextEmergency();
  }
}

// Function to handle runway clearance requests
void handleRunwayRequest() {
  if (!emergencyActive && runwayClear) {
    Serial.println("Clearance Granted: Aircraft may proceed.");
    digitalWrite(greenLED, HIGH); // Green LED on to signal clearance
    delay(3000);                  // Simulate runway usage (aircraft taking off/landing)
    resetRunway();                // Reset runway to clear state
  } else if (emergencyActive) {
    Serial.println("Emergency Override: Runway unavailable.");
  } else {
    Serial.println("Runway Occupied: Please wait.");
  }
}

// Function to reset the runway
void resetRunway() {
  runwayClear = true;
  digitalWrite(greenLED, LOW);  // Turn off green LED (runway is no longer cleared)
  Serial.println("Runway is now clear.");
}

// Function to activate emergency mode
void activateEmergency() {
  emergencyActive = true;
  digitalWrite(redLED, HIGH);   // Turn on red LED
  digitalWrite(buzzer, HIGH);   // Sound the buzzer
  Serial.println("Emergency Activated: Priority landing.");

  // Simulate emergency duration
  delay(2000);

  deactivateEmergency();
}

// Function to deactivate emergency mode
void deactivateEmergency() {
  emergencyActive = false;
  digitalWrite(redLED, LOW);    // Turn off red LED
  digitalWrite(buzzer, LOW);    // Turn off buzzer
  Serial.println("Emergency Cleared: Resuming normal operations.");
}

// Function to schedule the next random emergency
void scheduleNextEmergency() {
  lastEmergencyTime = millis();
  nextEmergencyDelay = 20000 + random(0, 10001);
  Serial.print("Next emergency in ");
  Serial.print(nextEmergencyDelay / 1000);
  Serial.println(" seconds.");
}

This code manages the runway clearance and emergency alerts. It uses the Arduino UNO to control LEDs, a buzzer, and an ultrasonic sensor. The code includes functions to handle runway requests, activate and deactivate emergencies, and schedule random emergencies.