ESP32 Voice-Activated Smart Relay Node

1#include <Arduino.h>
2#include <driver/i2s.h>
3
4// --- Pin Definitions ---
5#define I2S_WS      25
6#define I2S_SCK     32
7#define I2S_SD      33
8
9#define RELAY_PIN   26
10#define LED_TRIGGER  2
11#define LED_STATUS   4
12
13// --- Audio & Trigger Parameters ---
14#define I2S_PORT           I2S_NUM_0
15#define SAMPLE_RATE        16000
16#define BUFFER_LEN         512
17#define SOUND_THRESHOLD    250000000  // Amplitude threshold for command detection
18#define TRIGGER_COOLDOWN   800        // Milliseconds lockout between triggers
19
20// State Variables
21bool relayState = false;
22unsigned long lastTriggerTime = 0;
23int32_t audioBuffer[BUFFER_LEN];
24
25void setupI2S() {
26    i2s_config_t i2s_config = {
27        .mode = (i2s_mode_t)(I2S_MODE_MASTER | I2S_MODE_RX),
28        .sample_rate = SAMPLE_RATE,
29        .bits_per_sample = I2S_BITS_PER_SAMPLE_32BIT,
30        .channel_format = I2S_CHANNEL_FMT_ONLY_LEFT,
31        .communication_format = I2S_COMM_FORMAT_STAND_I2S,
32        .intr_alloc_flags = ESP_INTR_FLAG_LEVEL1,
33        .dma_buf_count = 4,
34        .dma_buf_len = BUFFER_LEN,
35        .use_apll = false,
36        .tx_desc_auto_clear = false,
37        .fixed_mclk = 0
38    };
39
40    i2s_pin_config_t pin_config = {
41        .bck_io_num = I2S_SCK,
42        .ws_io_num = I2S_WS,
43        .data_out_num = I2S_PIN_NO_CHANGE,
44        .data_in_num = I2S_SD
45    };
46
47    i2s_driver_install(I2S_PORT, &i2s_config, 0, NULL);
48    i2s_set_pin(I2S_PORT, &pin_config);
49    i2s_zero_dma_buffer(I2S_PORT);
50}
51
52void toggleRelay() {
53    relayState = !relayState;
54    digitalWrite(RELAY_PIN, relayState ? HIGH : LOW);
55    digitalWrite(LED_STATUS, relayState ? HIGH : LOW);
56}
57
58void setup() {
59    Serial.begin(115200);
60
61    pinMode(RELAY_PIN, OUTPUT);
62    pinMode(LED_TRIGGER, OUTPUT);
63    pinMode(LED_STATUS, OUTPUT);
64
65    // Initial safe states
66    digitalWrite(RELAY_PIN, LOW);
67    digitalWrite(LED_TRIGGER, LOW);
68    digitalWrite(LED_STATUS, LOW);
69
70    setupI2S();
71    Serial.println("Voice Relay Node Initialized. Listening...");
72}
73
74void loop() {
75    size_t bytesRead = 0;
76    esp_err_t result = i2s_read(I2S_PORT, &audioBuffer, sizeof(audioBuffer), &bytesRead, portMAX_DELAY);
77
78    if (result == ESP_OK && bytesRead > 0) {
79        int samplesRead = bytesRead / sizeof(int32_t);
80        int64_t sumEnergy = 0;
81
82        for (int i = 0; i < samplesRead; i++) {
83            // INMP441 provides 24-bit data MSB-aligned in 32-bit slot
84            int32_t sample = audioBuffer[i] >> 14; 
85            sumEnergy += (int64_t)sample * sample;
86        }
87
88        int64_t meanEnergy = sumEnergy / samplesRead;
89
90        // Acoustic threshold evaluation
91        if (meanEnergy > SOUND_THRESHOLD) {
92            unsigned long currentTime = millis();
93            if (currentTime - lastTriggerTime > TRIGGER_COOLDOWN) {
94                lastTriggerTime = currentTime;
95                
96                // Visual feedback pulse
97                digitalWrite(LED_TRIGGER, HIGH);
98                toggleRelay();
99                
100                Serial.printf("Voice Trigger Detected! Energy: %lld | Relay: %s\n", 
101                              meanEnergy, relayState ? "ON" : "OFF");
102                
103                delay(100);
104                digitalWrite(LED_TRIGGER, LOW);
105            }
106        }
107    }
108}