บทความ: สร้าง Energy Meter วัดกระแสไฟด้วย ESP32 และ SCT013 CT Clamp เชื่อมต่อ Home Assistant

/*
 * ESP32 Energy Meter ด้วย SCT013 CT Clamp
 * วัดกระแสไฟฟ้า AC และคำนวณพลังงาน (W) และพลังงานสะสม (kWh)
 * เชื่อมต่อกับ Home Assistant ผ่าน MQTT
 *
 * Hardware: ESP32 + SCT013-000 + Burden Resistor 33Ω
 * Author: CynoIoT
 * Date: April 2026
 */

#include <WiFi.h>
#include <PubSubClient.h>
#include <EmonLib.h>

// ===== WiFi Settings =====
const char* ssid = "YOUR_WIFI_SSID";
const char* password = "YOUR_WIFI_PASSWORD";

// ===== MQTT Settings =====
const char* mqtt_server = "homeassistant.local"; // IP หรือ Hostname ของ Home Assistant
const int mqtt_port = 1883;
const char* mqtt_user = "YOUR_MQTT_USER";
const char* mqtt_password = "YOUR_MQTT_PASSWORD";
const char* mqtt_client_id = "esp32_energy_meter";

// ===== CynoIoT Settings =====
const char* cynoiot_api_key = "YOUR_CYNOIOT_API_KEY";
const char* cynoiot_device_id = "YOUR_DEVICE_ID";

// ===== CT Clamp Settings =====
const int CT_PIN = 34; // GPIO 34 (ADC1_CH6)
const double ICAL = 60.6; // 100A / 50mA * Burden Resistor Factor = 60.6 (สำหรับ 33Ω)
const double VOLTAGE = 230.0; // แรงดันไฟฟ้าบ้าน (V) - ปรับตามพื้นที่

// ===== MQTT Topics =====
const char* mqtt_topic_current = "homeassistant/sensor/esp32_energy_meter/current";
const char* mqtt_topic_power = "homeassistant/sensor/esp32_energy_meter/power";
const char* mqtt_topic_energy = "homeassistant/sensor/esp32_energy_meter/energy";

// ===== Variables =====
EnergyMonitor emon1;
WiFiClient espClient;
PubSubClient mqtt_client(espClient);

unsigned long lastMillis = 0;
const long interval = 5000; // อ่านค่าทุกๆ 5 วินาที

double Irms = 0;
double power = 0;
double energy_kwh = 0;
unsigned long lastEnergyTime = 0;

// ===== WiFi Connect Function =====
void setup_wifi() {
  Serial.print("Connecting to ");
  Serial.println(ssid);

  WiFi.begin(ssid, password);

  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }

  Serial.println("");
  Serial.println("WiFi connected");
  Serial.println("IP address: ");
  Serial.println(WiFi.localIP());
}

// ===== MQTT Reconnect Function =====
void reconnect_mqtt() {
  while (!mqtt_client.connected()) {
    Serial.print("Attempting MQTT connection...");

    if (mqtt_client.connect(mqtt_client_id, mqtt_user, mqtt_password)) {
      Serial.println("connected");

      // MQTT Discovery สำหรับ Home Assistant
      // Current Sensor
      String current_config = "{"
        "\"name\":\"ESP32 Current\","
        "\"stat_t\":\"" + String(mqtt_topic_current) + "\","
        "\"unit_of_meas\":\"A\","
        "\"dev\":{\"ids\":\"esp32_energy_meter\"},"
        "\"uniq_id\":\"esp32_energy_meter_current\""
      "}";
      mqtt_client.publish("homeassistant/sensor/esp32_energy_meter_current/config", current_config.c_str(), true);

      // Power Sensor
      String power_config = "{"
        "\"name\":\"ESP32 Power\","
        "\"stat_t\":\"" + String(mqtt_topic_power) + "\","
        "\"unit_of_meas\":\"W\","
        "\"dev\":{\"ids\":\"esp32_energy_meter\"},"
        "\"uniq_id\":\"esp32_energy_meter_power\""
      "}";
      mqtt_client.publish("homeassistant/sensor/esp32_energy_meter_power/config", power_config.c_str(), true);

      // Energy Sensor
      String energy_config = "{"
        "\"name\":\"ESP32 Energy\","
        "\"stat_t\":\"" + String(mqtt_topic_energy) + "\","
        "\"unit_of_meas\":\"kWh\","
        "\"dev\":{\"ids\":\"esp32_energy_meter\"},"
        "\"uniq_id\":\"esp32_energy_meter_energy\","
        "\"state_class\":\"total_increasing\""
      "}";
      mqtt_client.publish("homeassistant/sensor/esp32_energy_meter_energy/config", energy_config.c_str(), true);

    } else {
      Serial.print("failed, rc=");
      Serial.print(mqtt_client.state());
      Serial.println(" try again in 5 seconds");
      delay(5000);
    }
  }
}

// ===== Send Data to CynoIoT =====
void send_to_cynoiot(double current, double pwr, double energy) {
  if (WiFi.status() == WL_CONNECTED) {
    HTTPClient http;
    http.begin("https://api.cynoiot.com/v1/devices/" + String(cynoiot_device_id) + "/data");
    http.addHeader("Content-Type", "application/json");
    http.addHeader("Authorization", "Bearer " + String(cynoiot_api_key));

    String payload = "{"
      "\"current\":" + String(current, 2) + ","
      "\"power\":" + String(pwr, 2) + ","
      "\"energy\":" + String(energy, 4) +
    "}";

    int httpResponseCode = http.POST(payload);

    if (httpResponseCode > 0) {
      Serial.print("CynoIoT Response: ");
      Serial.println(httpResponseCode);
    } else {
      Serial.print("CynoIoT Error: ");
      Serial.println(httpResponseCode);
    }

    http.end();
  }
}

void setup() {
  Serial.begin(115200);

  // Setup WiFi
  setup_wifi();

  // Setup MQTT
  mqtt_client.setServer(mqtt_server, mqtt_port);

  // Setup Energy Monitor
  emon1.current(CT_PIN, ICAL);

  Serial.println("ESP32 Energy Meter Started!");
  lastEnergyTime = millis();
}

void loop() {
  // MQTT Reconnect
  if (!mqtt_client.connected()) {
    reconnect_mqtt();
  }
  mqtt_client.loop();

  // Read Energy Values ทุกๆ 5 วินาที
  unsigned long currentMillis = millis();
  if (currentMillis - lastMillis >= interval) {
    lastMillis = currentMillis;

    // คำนวณเวลาที่ผ่านไป (ชั่วโมง)
    double hours_passed = (currentMillis - lastEnergyTime) / 3600000.0;

    // อ่านค่ากระแส (A)
    Irms = emon1.calcIrms(1480); // 1480 samples

    // คำนวณกำลังไฟฟ้า (W) = Current (A) × Voltage (V)
    power = Irms * VOLTAGE;

    // คำนวณพลังงานสะสม (kWh) = Power (W) × Time (h) / 1000
    energy_kwh += (power * hours_passed) / 1000.0;

    // แสดงผลใน Serial Monitor
    Serial.print("Current: ");
    Serial.print(Irms, 2);
    Serial.print("A | Power: ");
    Serial.print(power, 1);
    Serial.print("W | Energy: ");
    Serial.print(energy_kwh, 4);
    Serial.println("kWh");

    // ส่งค่าไป MQTT (Home Assistant)
    char current_str[10];
    char power_str[10];
    char energy_str[10];

    dtostrf(Irms, 2, 2, current_str);
    dtostrf(power, 2, 1, power_str);
    dtostrf(energy_kwh, 2, 4, energy_str);

    mqtt_client.publish(mqtt_topic_current, current_str);
    mqtt_client.publish(mqtt_topic_power, power_str);
    mqtt_client.publish(mqtt_topic_energy, energy_str);

    // ส่งค่าไป CynoIoT
    send_to_cynoiot(Irms, power, energy_kwh);
  }
}