code task3.3

#include <WiFiNINA.h>
#include <ArduinoMqttClient.h>

// Wi-Fi Credentials
#define ssid "OPTUS_FF9A94L"
#define pass "hazel20212qv"

// MQTT Broker Details
const char broker[] = "broker.emqx.io";
int port = 1883;
const char topic[] = "SIT210/wave";

// Wi-Fi & MQTT Clients
WiFiClient wifiClient;
MqttClient mqttClient(wifiClient);

// Ultrasonic Sensor Pins
const int trigPin = 2;
const int echoPin = 3;
// LED Pin
const int ledPin = 4;

// Last detection timestamp to prevent multiple triggers
unsigned long lastDetectionTime = 0;
const unsigned long debounceDelay = 3000; // 3 seconds debounce

void setup() {
  Serial.begin(9600);
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  pinMode(ledPin, OUTPUT);

  // Connect to Wi-Fi
  Serial.print("Connecting to Wi-Fi: ");
  Serial.println(ssid);
  while (WiFi.begin(ssid, pass) != WL_CONNECTED) {
    Serial.print(".");
    delay(2000);
  }
  Serial.println("\nConnected to Wi-Fi");

  // Connect to MQTT Broker
  Serial.print("Connecting to MQTT Broker: ");
  Serial.println(broker);
  while (!mqttClient.connect(broker, port)) {
    Serial.print("MQTT connection failed! Error code: ");
    Serial.println(mqttClient.connectError());
    delay(5000);
  }
  Serial.println("Connected to MQTT Broker");

  // Set callback function for receiving messages
  mqttClient.onMessage(onMqttMessage);

  // Subscribe to the topic
  mqttClient.subscribe(topic);
  Serial.println("Subscribed to topic: " + String(topic));
}

void loop() {
  mqttClient.poll(); // Check for new MQTT messages

  float distance = getDistance();

  // Debounce mechanism to prevent frequent triggers
  unsigned long currentMillis = millis();
  if (distance > 0 && distance <= 20 && (currentMillis - lastDetectionTime > debounceDelay)) {
    lastDetectionTime = currentMillis;
    if (distance > 10) {
      // Wave detected
      Serial.println("Wave detected!");
      mqttClient.beginMessage(topic);
      mqttClient.print("Ekamjot waved!");
      mqttClient.endMessage();
    } else {
      // Pat detected
      Serial.println("Pat detected!");
      mqttClient.beginMessage(topic);
      mqttClient.print("pat");
      mqttClient.endMessage();
    }
  }
}

// Function to measure distance using Ultrasonic Sensor
float getDistance() {
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);
  long duration = pulseIn(echoPin, HIGH);
  return (duration * 0.0343) / 2; // Convert time to distance in cm
}

// Function to handle received MQTT messages
void onMqttMessage(int messageSize) {
  Serial.print("Received message on topic '");
  Serial.print(mqttClient.messageTopic());
  Serial.print("': ");

  String message = "";
  while (mqttClient.available()) {
    char c = (char)mqttClient.read();
    message += c;
    Serial.print(c);
  }
  Serial.println();

  // Determine action based on received message
  if (message == "Ekamjot waved!") {
    flashLed(3, 500); // Wave: Slow flash 3 times
  } else if (message == "pat") {
    flashLed(5, 200); // Pat: Fast flash 5 times
  }
}

// Function to flash LED a given number of times with a specified delay
void flashLed(int times, int delayMs) {
  for (int i = 0; i < times; i++) {
    digitalWrite(ledPin, HIGH);
    delay(delayMs);
    digitalWrite(ledPin, LOW);
    delay(delayMs);
  }
}