M5StickC Plus2 と CO2センサーで室内の CO2 濃度を計測し、AWS IoT Core でデータを可視化してみた

/**
 * ================================================
 * M5StickC Plus2 CO2 Sensor - AWS IoT Core Integration
 * ================================================
 */

#include <M5StickCPlus2.h>
#include <Wire.h>
#include <SensirionI2cScd4x.h>
#include <WiFi.h>
#include <WiFiClientSecure.h>
#include <PubSubClient.h>
#include <SPIFFS.h>

// ================================================
// AWS IoT Core 設定
// ================================================
const char* AWS_IOT_ENDPOINT = "a2ohov8mh1yeba-ats.iot.ap-northeast-1.amazonaws.com";
const int AWS_IOT_PORT = 8883;
const char* CLIENT_ID = "m5-co2-sensor";

// ================================================
// MQTT トピック設定
// ================================================
const char* PUBLISH_TOPIC = "sensor/co2";

// ================================================
// グローバル変数
// ================================================
SensirionI2cScd4x scd4x;
WiFiClientSecure wifiClient;
PubSubClient mqttClient(wifiClient);

String wifiSSID;
String wifiPassword;

// ================================================
// ユーティリティ関数
// ================================================
String readFile(const char* path) {
  File file = SPIFFS.open(path, "r");
  if (!file) {
    Serial.print("Failed to open file: ");
    Serial.println(path);
    return "";
  }

  String content = "";
  while (file.available()) {
    content += (char)file.read();
  }
  file.close();
  content.trim();
  return content;
}

// ================================================
// WiFi 接続
// ================================================
void connectWiFi() {
  M5.Display.fillScreen(BLACK);
  M5.Display.setCursor(5, 10);
  M5.Display.setTextSize(1);
  M5.Display.println("Connecting WiFi...");

  Serial.println("\n=== WiFi Connection ===");
  Serial.print("SSID: ");
  Serial.println(wifiSSID);

  WiFi.begin(wifiSSID.c_str(), wifiPassword.c_str());

  int attempts = 0;
  while (WiFi.status() != WL_CONNECTED && attempts < 20) {
    delay(500);
    Serial.print(".");
    attempts++;
  }

  if (WiFi.status() == WL_CONNECTED) {
    Serial.println("\nWiFi Connected!");
    Serial.print("IP Address: ");
    Serial.println(WiFi.localIP());

    M5.Display.fillScreen(BLACK);
    M5.Display.setCursor(5, 10);
    M5.Display.println("WiFi Connected!");
    M5.Display.setCursor(5, 30);
    M5.Display.print("IP: ");
    M5.Display.println(WiFi.localIP());
    delay(2000);
  } else {
    Serial.println("\nWiFi Connection Failed!");
    M5.Display.fillScreen(RED);
    M5.Display.setCursor(5, 50);
    M5.Display.println("WiFi Failed!");
    while (1) delay(1000);
  }
}

// ================================================
// AWS IoT Core 接続
// ================================================
void connectAWS() {
  Serial.println("\n=== AWS IoT Core Connection ===");
  Serial.println("Loading certificates from SPIFFS...");

  String rootCA = readFile("/rootCA.pem");
  String cert = readFile("/cert.pem");
  String privateKey = readFile("/private.key");

  if (rootCA.isEmpty() || cert.isEmpty() || privateKey.isEmpty()) {
    Serial.println("ERROR: Failed to load certificates!");
    M5.Display.fillScreen(RED);
    M5.Display.setCursor(5, 50);
    M5.Display.println("Cert Load Failed!");
    while (1) delay(1000);
  }

  Serial.println("Certificates loaded successfully");

  wifiClient.setCACert(rootCA.c_str());
  wifiClient.setCertificate(cert.c_str());
  wifiClient.setPrivateKey(privateKey.c_str());

  mqttClient.setServer(AWS_IOT_ENDPOINT, AWS_IOT_PORT);

  M5.Display.fillScreen(BLACK);
  M5.Display.setCursor(5, 10);
  M5.Display.println("Connecting AWS...");

  int attempts = 0;
  while (!mqttClient.connected() && attempts < 5) {
    Serial.print("Attempt ");
    Serial.print(attempts + 1);
    Serial.println(": Connecting to AWS IoT Core...");

    if (mqttClient.connect(CLIENT_ID)) {
      Serial.println("✓ AWS IoT Connected!");

      M5.Display.fillScreen(BLACK);
      M5.Display.setCursor(5, 10);
      M5.Display.println("AWS Connected!");
      delay(1000);
    } else {
      Serial.print("✗ Failed, rc=");
      Serial.println(mqttClient.state());

      switch (mqttClient.state()) {
        case -4: Serial.println("  → Timeout"); break;
        case -3: Serial.println("  → Connection lost"); break;
        case -2: Serial.println("  → Network failed"); break;
        case 2:  Serial.println("  → Authentication failed"); break;
        case 5:  Serial.println("  → Unauthorized"); break;
      }

      Serial.println("  Retrying in 5s...");
      delay(5000);
      attempts++;
    }
  }

  if (!mqttClient.connected()) {
    Serial.println("ERROR: AWS Connection Failed!");
    M5.Display.fillScreen(RED);
    M5.Display.setCursor(5, 50);
    M5.Display.println("AWS Failed!");
  }
}

// ================================================
// センサーデータ送信
// ================================================
void publishSensorData(uint16_t co2, float temperature, float humidity) {
  String payload = "{";
  payload += "\"co2\":" + String(co2) + ",";
  payload += "\"temperature\":" + String(temperature, 1) + ",";
  payload += "\"humidity\":" + String(humidity, 1) + ",";
  payload += "\"timestamp\":\"" + String(millis()) + "\"";
  payload += "}";

  Serial.println("\n=== Publishing Data ===");
  Serial.print("Topic: ");
  Serial.println(PUBLISH_TOPIC);
  Serial.print("Payload: ");
  Serial.println(payload);

  if (mqttClient.publish(PUBLISH_TOPIC, payload.c_str())) {
    Serial.println("✓ Published successfully!");
  } else {
    Serial.println("✗ Publish failed!");
    Serial.print("MQTT State: ");
    Serial.println(mqttClient.state());
  }
}

// ================================================
// 初期化（setup）
// ================================================
void setup() {
  M5.begin();
  Serial.begin(115200);

  M5.Display.setRotation(1);
  M5.Display.fillScreen(BLACK);
  M5.Display.setTextColor(WHITE);
  M5.Display.setTextSize(1);

  Serial.println("\n\n====================================");
  Serial.println("  M5StickC Plus2 CO2 Sensor");
  Serial.println("  AWS IoT Core Integration");
  Serial.println("====================================\n");

  Serial.println("Step 1: Initializing SPIFFS...");
  if (!SPIFFS.begin(true)) {
    Serial.println("ERROR: SPIFFS initialization failed!");
    M5.Display.fillScreen(RED);
    M5.Display.setCursor(5, 50);
    M5.Display.println("SPIFFS Failed!");
    while (1) delay(1000);
  }
  Serial.println("✓ SPIFFS initialized");

  Serial.println("\nStep 2: Loading WiFi credentials...");
  wifiSSID = readFile("/wifi_ssid.txt");
  wifiPassword = readFile("/wifi_password.txt");

  if (wifiSSID.isEmpty() || wifiPassword.isEmpty()) {
    Serial.println("ERROR: WiFi credentials not found!");
    M5.Display.fillScreen(RED);
    M5.Display.setCursor(5, 50);
    M5.Display.println("WiFi Config Missing!");
    while (1) delay(1000);
  }
  Serial.println("✓ WiFi credentials loaded");

  Serial.println("\nStep 3: Connecting to WiFi...");
  connectWiFi();

  Serial.println("\nStep 4: Connecting to AWS IoT Core...");
  connectAWS();

  Serial.println("\nStep 5: Initializing CO2 sensor...");
  Wire.begin(32, 33);
  scd4x.begin(Wire, 0x62);
  scd4x.stopPeriodicMeasurement();
  delay(500);
  scd4x.startPeriodicMeasurement();

  Serial.println("✓ CO2 sensor initialized");
  Serial.println("\nWaiting 5 seconds for first measurement...");
  delay(5000);

  Serial.println("\n====================================");
  Serial.println("  Setup Complete!");
  Serial.println("  Starting main loop...");
  Serial.println("====================================\n");
}

// ================================================
// メインループ（loop）
// ================================================
void loop() {
  if (!mqttClient.connected()) {
    Serial.println("MQTT disconnected. Reconnecting...");
    connectAWS();
  }

  mqttClient.loop();

  uint16_t co2 = 0;
  float temperature = 0.0f;
  float humidity = 0.0f;

  uint16_t error = scd4x.readMeasurement(co2, temperature, humidity);

  if (error == 0 && co2 > 0) {
    Serial.println("\n--- Sensor Data ---");
    Serial.print("CO2: ");
    Serial.print(co2);
    Serial.println(" ppm");
    Serial.print("Temperature: ");
    Serial.print(temperature, 1);
    Serial.println(" °C");
    Serial.print("Humidity: ");
    Serial.print(humidity, 1);
    Serial.println(" %");
    Serial.println("-------------------");

    publishSensorData(co2, temperature, humidity);

    M5.Display.fillScreen(BLACK);

    M5.Display.setCursor(5, 10);
    M5.Display.setTextSize(2);
    M5.Display.println("CO2 Sensor");

    M5.Display.setCursor(5, 35);
    M5.Display.setTextSize(3);
    M5.Display.print(co2);
    M5.Display.setTextSize(2);
    M5.Display.println(" ppm");

    M5.Display.setCursor(5, 70);
    M5.Display.setTextSize(2);
    M5.Display.print("Temp: ");
    M5.Display.print(temperature, 1);
    M5.Display.println(" C");

    M5.Display.setCursor(5, 95);
    M5.Display.setTextSize(2);
    M5.Display.print("Hum: ");
    M5.Display.print(humidity, 1);
    M5.Display.println(" %");

  } else {
    Serial.print("Error reading sensor: ");
    Serial.println(error);
  }

  delay(10000);
}