ระบบตรวจจับทิศทางเสียงปืน
ด้วย ESP32-S3 + TDOA Array

/*
 * Gunshot Detection & Direction Vector Indicator System v2.0
 * Target: ESP32-S3 · 4x INMP441 I2S Microphone Array · 5x LED Direction Indicators
 * Algorithm: GCC-PHAT Time Difference of Arrival (TDOA)
 * Published: e25vbe.radio · MIT License · Open Design for Border Monitoring
 */

#include <Arduino.h>
#include <driver/i2s.h>
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "tdoa.h"

// ── GPIO Pin Definitions ──────────────────────────────────────
#define LED_N      4    // North LED  → GPIO 4
#define LED_S      5    // South LED  → GPIO 5
#define LED_E      6    // East LED   → GPIO 6
#define LED_W      7    // West LED   → GPIO 7
#define LED_CTR    11   // Status LED → GPIO 11

#define I2S_BCK     9   // Bit Clock (shared all mics)
#define I2S_DATA    8   // Data line (shared all mics)
#define I2S_WS_MIC1 15  // Word Select · MIC 1 North
#define I2S_WS_MIC2 16  // Word Select · MIC 2 South
#define I2S_WS_MIC3 17  // Word Select · MIC 3 East
#define I2S_WS_MIC4 18  // Word Select · MIC 4 West

// ── Signal Detection Parameters ──────────────────────────────
#define SAMPLE_RATE        44100   // Hz
#define BUFFER_SIZE        512     // samples per DMA block
#define AMPLITUDE_THRESH   180000  // ADC counts - calibrate on site
#define INDICATOR_HOLD_MS  3000    // LED lock time after detection (ms)
#define MIC_SPACING_M      1.0f    // meters between opposing microphones
#define SPEED_SOUND_MS     0.344f  // m per millisecond @ 20°C

// ── Shared buffers between cores ─────────────────────────────
volatile int32_t buf_n[BUFFER_SIZE];
volatile int32_t buf_s[BUFFER_SIZE];
volatile int32_t buf_e[BUFFER_SIZE];
volatile int32_t buf_w[BUFFER_SIZE];
volatile bool    data_ready = false;
volatile bool    event_detected = false;
volatile float   last_bearing_deg = 0;

// ── I2S driver setup ─────────────────────────────────────────
void i2s_install(i2s_port_t port, int ws_pin) {
    i2s_config_t cfg = {
        .mode            = (i2s_mode_t)(I2S_MODE_MASTER | I2S_MODE_RX),
        .sample_rate     = SAMPLE_RATE,
        .bits_per_sample = I2S_BITS_PER_SAMPLE_32BIT,
        .channel_format  = I2S_CHANNEL_FMT_ONLY_LEFT,
        .communication_format = I2S_COMM_FORMAT_STAND_I2S,
        .intr_alloc_flags = ESP_INTR_FLAG_LEVEL1,
        .dma_buf_count   = 4,
        .dma_buf_len     = BUFFER_SIZE,
        .use_apll        = true
    };
    i2s_pin_config_t pins = {
        .bck_io_num   = I2S_BCK,
        .ws_io_num    = ws_pin,
        .data_out_num = I2S_PIN_NO_CHANGE,
        .data_in_num  = I2S_DATA
    };
    i2s_driver_install(port, &cfg, 0, NULL);
    i2s_set_pin(port, &pins);
}

// ── LED helpers ───────────────────────────────────────────────
void led_setup() {
    for (int p : {LED_N, LED_S, LED_E, LED_W, LED_CTR})
        pinMode(p, OUTPUT);
    // Boot flash sequence
    for (int p : {LED_N, LED_E, LED_S, LED_W, LED_CTR}) {
        digitalWrite(p, HIGH); delay(80); digitalWrite(p, LOW);
    }
}

void led_clear() {
    digitalWrite(LED_N, LOW); digitalWrite(LED_S, LOW);
    digitalWrite(LED_E, LOW); digitalWrite(LED_W, LOW);
}

void led_direction(float bearing) {
    led_clear();
    // Light the LED(s) corresponding to the arrival direction quadrant
    if (bearing >= 315 || bearing < 45)  digitalWrite(LED_N, HIGH);
    if (bearing >= 45  && bearing < 135) digitalWrite(LED_E, HIGH);
    if (bearing >= 135 && bearing < 225) digitalWrite(LED_S, HIGH);
    if (bearing >= 225 && bearing < 315) digitalWrite(LED_W, HIGH);
}

// ── Core 0 Task: I2S Capture ──────────────────────────────────
void taskCapture(void* param) {
    size_t bytes;
    while (true) {
        i2s_read(I2S_NUM_0, (void*)buf_n, BUFFER_SIZE*4, &bytes, portMAX_DELAY);
        i2s_read(I2S_NUM_1, (void*)buf_s, BUFFER_SIZE*4, &bytes, portMAX_DELAY);
        // MIC3/4 share I2S_NUM_0 via L/R channel split in production
        data_ready = true;
        vTaskDelay(1 / portTICK_PERIOD_MS);
    }
}

// ── Core 1 Task: TDOA + LED ───────────────────────────────────
void taskProcess(void* param) {
    while (true) {
        if (!data_ready) { vTaskDelay(2 / portTICK_PERIOD_MS); continue; }
        data_ready = false;

        // Peak amplitude check (fast path)
        int32_t peak = peak_amplitude(buf_n, BUFFER_SIZE);
        if (peak < AMPLITUDE_THRESH) {
            // Heartbeat blink
            digitalWrite(LED_CTR, HIGH); vTaskDelay(20/portTICK_PERIOD_MS);
            digitalWrite(LED_CTR, LOW);
            continue;
        }

        // ── Gunshot Detected! ──────────────────────────────────
        digitalWrite(LED_CTR, HIGH);
        Serial.printf("[ALERT] Peak=%d · running TDOA\n", peak);

        float dt_ns = gcc_phat_delay(buf_n, buf_s, BUFFER_SIZE, SAMPLE_RATE);
        float dt_ew = gcc_phat_delay(buf_e, buf_w, BUFFER_SIZE, SAMPLE_RATE);

        // Convert delay to bearing angle
        float sin_el = (dt_ns * SPEED_SOUND_MS * 1000) / MIC_SPACING_M;
        float sin_az = (dt_ew * SPEED_SOUND_MS * 1000) / MIC_SPACING_M;
        sin_el = constrain(sin_el, -1.0f, 1.0f);
        sin_az = constrain(sin_az, -1.0f, 1.0f);

        float bearing = atan2f(sin_az, sin_el) * 180.0f / PI;
        if (bearing < 0) bearing += 360;
        last_bearing_deg = bearing;

        Serial.printf("[DIRECTION] Bearing=%.1f° dt_NS=%.2fms dt_EW=%.2fms\n",
                      bearing, dt_ns*1000, dt_ew*1000);

        led_direction(bearing);
        vTaskDelay(INDICATOR_HOLD_MS / portTICK_PERIOD_MS);
        led_clear();
        digitalWrite(LED_CTR, LOW);
    }
}

// ── Setup ─────────────────────────────────────────────────────
void setup() {
    Serial.begin(115200);
    led_setup();
    i2s_install(I2S_NUM_0, I2S_WS_MIC1);
    i2s_install(I2S_NUM_1, I2S_WS_MIC2);
    Serial.println("[INIT] Gunshot Detection Array v2.0 standing by...");

    xTaskCreatePinnedToCore(taskCapture, "I2S_CAP",  4096, NULL, 2, NULL, 0);
    xTaskCreatePinnedToCore(taskProcess, "TDOA_PROC", 8192, NULL, 1, NULL, 1);
}

void loop() {
    vTaskDelay(100 / portTICK_PERIOD_MS); // Unused; logic runs on FreeRTOS tasks
}