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+<code C 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");
+  }
+}
+</code>