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main.cpp

#include <Arduino.h>
#include <WiFi.h>
#include <Wire.h>
#include <MQTT.h>              
#include <ArduinoJson.h>
#include <Adafruit_BME680.h>
 
//////////////// EDIT THESE ////////////////
const char* WIFI_SSID     = "YOUR_SSID";
const char* WIFI_PASSWORD = "YOUR_PASSWORD";
const char* MQTT_HOST     = "test.mosquitto.org";   // or your lab broker
const uint16_t MQTT_PORT  = 1883;
const char* BASE_TOPIC    = "iot/studentname";        // change per student
////////////////////////////////////////////
 
// Sparrow I2C: SDA=21, SCL=22
#define SDA_PIN 21
#define SCL_PIN 22
Adafruit_BME680 bme;  // I2C
 
WiFiClient net;
MQTTClient mqtt(1024);   // 1KB message buffer
 
void ensureWiFi() {
  if (WiFi.status() == WL_CONNECTED) return;
  WiFi.mode(WIFI_STA);
  WiFi.begin(WIFI_SSID, WIFI_PASSWORD);
  Serial.print("WiFi connecting");
  while (WiFi.status() != WL_CONNECTED) {
    delay(400);
    Serial.print(".");
  }
  Serial.printf("\nIP: %s\n", WiFi.localIP().toString().c_str());
}
 
void ensureMQTT() {
  if (mqtt.connected()) return;
 
  // Optional Last Will so dashboards see offline state
  String willTopic = String(BASE_TOPIC) + "/bme688/status";
  mqtt.setWill(willTopic.c_str(), "offline", true, 1);
 
  String cid = String("sparrow-c6-sense-") + String((uint32_t)ESP.getEfuseMac(), HEX);
  Serial.println("MQTT connecting...");
  while (!mqtt.connect(cid.c_str())) {
    Serial.print(".");
    delay(1000);
  }
  Serial.println("\nMQTT connected");
 
  // Publish "online" status retained
  mqtt.publish(willTopic, "online", true, 1);
}
 
unsigned long lastPub = 0;
 
void setup() {
  Serial.begin(115200);
  delay(200);
 
  Wire.begin(SDA_PIN, SCL_PIN);
 
  // MQTT broker + transport
  mqtt.begin(MQTT_HOST, MQTT_PORT, net);
 
  if (!bme.begin(0x76)) {           // Sparrow uses 0x76
    Serial.println("BME688 not found!");
    for(;;) { delay(1000); }
  }
  // Reasonable oversampling; heater off for simplicity
  bme.setTemperatureOversampling(BME680_OS_8X);
  bme.setHumidityOversampling(BME680_OS_2X);
  bme.setPressureOversampling(BME680_OS_4X);
  bme.setIIRFilterSize(BME680_FILTER_SIZE_3);
  bme.setGasHeater(0, 0);  // off
}
 
void loop() {
  ensureWiFi();
  ensureMQTT();
 
  mqtt.loop();     // process incoming/keepalive
  delay(10);
 
  if (millis() - lastPub > 10000) {
    lastPub = millis();
 
    if (!bme.performReading()) {
      Serial.println("BME read failed");
      return;
    }
 
    // Build JSON (ArduinoJson v7 style, no deprecated StaticJsonDocument)
    JsonDocument doc;
    doc["ts"]        = (uint32_t)(millis() / 1000);
    doc["temp_c"]    = bme.temperature;
    doc["hum_pct"]   = bme.humidity;
    doc["press_hpa"] = bme.pressure / 100.0;
    doc["gas_ohm"]   = bme.gas_resistance;
 
    String payload;
    serializeJson(doc, payload);
 
    String topic = String(BASE_TOPIC) + "/bme688";
    bool ok = mqtt.publish(topic, payload);  // QoS0, non-retained
    Serial.printf("Pub %s => %s (%s)\n",
                  topic.c_str(), payload.c_str(), ok ? "OK" : "FAIL");
  }
}