final_code

#include <Arduino.h>

// ------------------- PINS -------------------
const int TRIG_PIN = 5;    // Ultrasonic Trig
const int ECHO_PIN = 18;   // Ultrasonic Echo
const int TONE_PIN = 25;   // Grove Speaker

// ------------------- AUDIO CONFIG -------------------
const int NUM_LAYERS = 6;
const float BASE_FREQ = 40.0;
float globalPhase = 0.0;

// ------------------- DYNAMIC VARIABLES -------------------
float RISE_SPEED = 0.0001; 
unsigned long lastSensorTime = 0;

// ------------------- HELPER FUNCTIONS -------------------
float getDistance() {
    digitalWrite(TRIG_PIN, LOW);
    delayMicroseconds(2);
    digitalWrite(TRIG_PIN, HIGH);
    delayMicroseconds(10);
    digitalWrite(TRIG_PIN, LOW);
    
    // Timeout 15ms (~2.5m)
    long duration = pulseIn(ECHO_PIN, HIGH, 15000); 
    if (duration == 0) return 150.0; // Assume far if error
    return duration * 0.034 / 2;
}

void setup() {
    Serial.begin(115200);
    
    pinMode(TRIG_PIN, OUTPUT);
    pinMode(ECHO_PIN, INPUT);

    // Audio Setup
    for (int i = 0; i < NUM_LAYERS; i++) {
        #if ESP_ARDUINO_VERSION >= ESP_ARDUINO_VERSION_VAL(3, 0, 0)
            ledcAttach(TONE_PIN, 5000, 8); 
        #else
            ledcSetup(i, 5000, 8); 
            ledcAttachPin(TONE_PIN, i);
        #endif
    }
    
    Serial.println("--- SHEPARD SIREN STARTED ---");
    Serial.println("Move object closer to see distance change...");
}

void loop() {
    // ------------------- SENSOR LOGIC -------------------
    if (millis() - lastSensorTime > 60) {
        lastSensorTime = millis();
        
        float dist = getDistance();
        
        // Clamp distance: 5cm (Danger) to 150cm (Safe)
        float d_clamped = constrain(dist, 5.0, 150.0);
        
        // Calculate Urgency (0.0 = Far, 1.0 = Close)
        float urgency = 1.0 - (d_clamped - 5.0) / 145.0; 
        
        // Extreme "Power of 4" Curve
        float minSpeed = 0.00005; 
        float maxSpeed = 0.04;    
        
        RISE_SPEED = minSpeed + (maxSpeed * pow(urgency, 4));

        // --- DISPLAY DISTANCE IN TERMINAL ---
        Serial.print("Distance: "); 
        Serial.print(dist); 
        Serial.print(" cm  |  Rise Speed: "); 
        Serial.println(RISE_SPEED, 6); 
    }

    // ------------------- AUDIO LOGIC -------------------
    globalPhase += RISE_SPEED;
    if (globalPhase >= 1.0) globalPhase -= 1.0;

    for (int i = 0; i < NUM_LAYERS; i++) {
        float layerPos = (float)i + globalPhase;
        float freq = BASE_FREQ * pow(2.0, layerPos);
        float relPos = layerPos / (float)NUM_LAYERS; 
        
        // Hanning Window
        float volumeTarget = 0.5 * (1.0 - cos(2.0 * PI * relPos));
        
        int duty = (int)(volumeTarget * (150.0 / NUM_LAYERS));

        if (freq > 30 && freq < 12000) {
            ledcWriteTone(i, (uint32_t)freq);
            ledcWrite(i, duty);
        } else {
            ledcWrite(i, 0); 
        }
    }

    delay(30); 
}