Remote Air Pollution Monitoring for Industrial Zones

#include <WisBlock-api.h>      // For RAK WisBlock APIs
#include <TinyGsmClient.h>     // General header for TinyGSM library
#include <TinyGsmClientSIM7600.h> // Header for SIM7600/BG77 modem family used by RAK3372
#include <PubSubClient.h>      // For MQTT communication (with Datacake)
#include <Wire.h>              // For I2C communication (for BME680)
#include <Adafruit_Sensor.h>   // Base class for Adafruit sensor libraries
#include <Adafruit_BME680.h>   // For RAK1906 (uses BME680 sensor)

// MQTT and Datacake Settings
// These values must be obtained from your Datacake dashboard and device registrations.
const char* MQTT_BROKER = "mqtt.datacake.co"; // Datacake MQTT broker address
const int MQTT_PORT = 1883;                   // MQTT port (8883 can also be used for TLS)
const char* MQTT_USERNAME = "YOUR_DATACAKE_MQTT_USERNAME"; // <<< CHANGE THIS
const char* MQTT_PASSWORD = "YOUR_DATACAKE_MQTT_PASSWORD"; // <<< CHANGE THIS
const char* MQTT_CLIENT_ID = "YOUR_DATACAKE_MQTT_CLIENT_ID"; // <<< CHANGE THIS
const char* MQTT_TOPIC = "dtc/v3/YOUR_DATACAKE_DEVICE_UUID/measurement"; // <<< CHANGE THIS

// GPRS connection information
const char apn[]  = "YOUR_APN";       // <<< CHANGE THIS (Your mobile operator's APN)
const char gprsUser[] = "";           // APN username (usually left blank)
const char gprsPass[] = "";           // APN password (usually left blank)

// Hardware Objects
TinyGsm modem(Serial1); // Serial port for RAK3372 modem (UART1)
TinyGsmClient client(modem); // TinyGSM client (TCP connection via modem)
PubSubClient mqttClient(client); // MQTT client

Adafruit_BME680 bme; // RAK1906 (BME680) environmental sensor object

// Timer Variables
long lastSendTime = 0;
const long sendInterval = 300000; // Data transmission interval: 5 minutes (5 * 60 * 1000 ms)

void setup() {
  // Start serial communication (for debug messages)
  Serial.begin(115200);
  while (!Serial); // Wait for serial port to be ready
  Serial.println("Industrial Air Pollution Monitoring Starting...");

  // Initialize RAK1906 (BME680) sensor
  Wire.begin(); // Start I2C communication
  if (!bme.begin(0x76)) { // I2C address is typically 0x76 or 0x77.
    Serial.println("RAK1906 BME680 not found, check connection!");
    while (1); // Stay in infinite loop if initialization fails
  }
  // Sampling and gas heater settings for BME680 (for VOC detection)
  bme.setTemperatureOversampling(BME680_OS_8X);
  bme.setHumidityOversampling(BME680_OS_2X);
  bme.setGasHeater(320, 150); // Heater settings for gas sensor (320°C, 150ms)
  Serial.println("RAK1906 BME680 successfully initialized.");

  // Initialize RAK3372 modem
  Serial1.begin(115200); // Set UART1 speed for RAK3372
  delay(100); // Small delay for modem to start
  Serial.println("Modem initializing...");
  modem.restart(); // Restart modem
  Serial.print("Modem Info: ");
  Serial.println(modem.getModemInfo()); // Get modem information

  // Try to connect to GPRS network
  Serial.print("Connecting to GPRS network...");
  if (!modem.gprsConnect(apn, gprsUser, gprsPass)) {
    Serial.println("GPRS connection failed! Please check APN settings and SIM card.");
    while (true); // Stay in infinite loop if connection fails
  }
  Serial.println("GPRS connection successful!");

  // Set MQTT server connection details (Datacake)
  mqttClient.setServer(MQTT_BROKER, MQTT_PORT);
  // Set MQTT Callback function (to handle commands from Datacake)
  mqttClient.setCallback(mqttCallback);

  connectMqtt(); // Try to connect to MQTT broker
  lastSendTime = millis(); // Initialize timer
}

void loop() {
  modem.maintainConnections(); // Keep GPRS connection active
  
  // Run MQTT client loop (to send and receive messages)
  if (!mqttClient.connected()) {
    connectMqtt(); // Try to reconnect if disconnected
  }
  mqttClient.loop();

  // Check if it's time to send data
  if (millis() - lastSendTime > sendInterval) {
    sendData();       // Send sensor data
    lastSendTime = millis(); // Reset timer
  }
}

// Function to manage connecting to MQTT broker
void connectMqtt() {
  Serial.print("Connecting to MQTT...");
  // Stay in loop until connection is successful
  while (!mqttClient.connected()) {
    // Connect to MQTT with client ID, username, and password (as required by Datacake)
    if (mqttClient.connect(MQTT_CLIENT_ID, MQTT_USERNAME, MQTT_PASSWORD)) {
      Serial.println("connected.");
      // If you expect to receive commands from Datacake, you can subscribe to the relevant topic here.
      // mqttClient.subscribe("dtc/v3/YOUR_DATACAKE_DEVICE_UUID/command"); 
    } else {
      Serial.print("failed, rc=");
      Serial.print(mqttClient.state()); // Print error code
      Serial.println(" trying again in 5 seconds");
      delay(5000); // Wait before retrying
    }
  }
}

// Callback function to process incoming messages (downlink) via MQTT
void mqttCallback(char* topic, byte* payload, unsigned int length) {
  Serial.print("Message Received - Topic: ");
  Serial.println(topic);
  Serial.print("Message: ");
  for (int i = 0; i < length; i++) {
    Serial.print((char)payload[i]);
  }
  Serial.println();
  // You can add code here to make the device react to incoming commands.
}

// Function to collect sensor data and send it to Datacake
void sendData() {
  // Start BME680 reading
  if (!bme.performReading()) {
    Serial.println("BME680 reading failed!");
    return; // Exit function if reading fails
  }
  
  float temperature = bme.temperature; // Temperature value
  float humidity = bme.humidity;       // Humidity value
  float gas_resistance = bme.gas_resistance / 1000.0; // Gas resistance (Ohms to KiloOhms)

  // Print read data to Serial Monitor
  Serial.printf("Temperature: %.2f C, Humidity: %.2f %%RH, Gas Resistance: %.2f KOhms\n", temperature, humidity, gas_resistance);

  // Create a JSON formatted payload (in the format expected by Datacake)
  String jsonPayload = "{\"temperature\":";
  jsonPayload += String(temperature, 2); // 2 decimal places
  jsonPayload += ",\"humidity\":";
  jsonPayload += String(humidity, 2);   // 2 decimal places
  jsonPayload += ",\"gas_resistance\":";
  jsonPayload += String(gas_resistance, 2); // 2 decimal places
  jsonPayload += "}";

  Serial.print("Sending Data: ");
  Serial.println(jsonPayload);

  // Publish the created JSON payload to the relevant topic in Datacake
  if (mqttClient.publish(MQTT_TOPIC, jsonPayload.c_str())) {
    Serial.println("Data successfully sent to Datacake.");
  } else {
    Serial.println("Data sending failed!");
  }
}