Final Project: IoT Environmental Dashboard

배터리 구동 센서 노드가 MQTT 브로커에 온습도를 스트리밍하고 웹 대시보드에 라이브 데이터 표시.

Project Overview

Bring together Units 3 (Wi-Fi), 5 (MQTT), 6 (DHT22), and 7 (Deep Sleep) into a complete battery-powered environmental monitoring node.

The node:

1. Wakes from deep sleep every N minutes
2. Connects to Wi-Fi and MQTT broker
3. Reads temperature + humidity from DHT22
4. Publishes to pailab/env/temperature and pailab/env/humidity
5. Returns to deep sleep

A Node-RED (or similar) dashboard subscribes to these topics and plots historical graphs.

Bill of Materials

Firmware

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

// — Configuration ——————————————————————————————————————
const char* SSID       = "YourSSID";
const char* PASSWORD   = "YourPass";
const char* BROKER     = "broker.hivemq.com";
const char* CLIENT_ID  = "esp32-env-01";
const long  SLEEP_SEC  = 300; // 5 minutes

#define DHT_PIN 4
// ———————————————————————————————————————————————————————

DHT dht(DHT_PIN, DHT22);
WiFiClient   wifiClient;
PubSubClient mqtt(wifiClient);

RTC_DATA_ATTR int wakeCount = 0;

bool connectWiFi() {
  WiFi.begin(SSID, PASSWORD);
  int tries = 0;
  while (WiFi.status() != WL_CONNECTED && tries < 20) {
    delay(500); tries++;
  }
  return WiFi.status() == WL_CONNECTED;
}

bool connectMQTT() {
  mqtt.setServer(BROKER, 1883);
  return mqtt.connect(CLIENT_ID);
}

void publish(const char* topic, float value) {
  char buf[16];
  snprintf(buf, sizeof(buf), "%.1f", value);
  mqtt.publish(topic, buf);
}

void setup() {
  Serial.begin(115200);
  wakeCount++;
  dht.begin();
  delay(2000); // DHT22 stabilise

  float t = dht.readTemperature();
  float h = dht.readHumidity();

  if (!isnan(t) && connectWiFi() && connectMQTT()) {
    publish("pailab/env/temperature", t);
    publish("pailab/env/humidity",    h);
    publish("pailab/env/wakes",       wakeCount);
    mqtt.loop();
    Serial.printf("Published T:%.1f H:%.0f wake:%d\n", t, h, wakeCount);
  } else {
    Serial.println("Sensor read or connection failed");
  }

  WiFi.disconnect(true);
  esp_sleep_enable_timer_wakeup((uint64_t)SLEEP_SEC * 1000000ULL);
  esp_deep_sleep_start();
}

void loop() {}

Dashboard with Node-RED

1. Install Node-RED: npm install -g --unsafe-perm node-red
2. Run: node-red
3. Open http://localhost:1880
4. Add: mqtt in → chart (node-red-dashboard) for each topic
5. Deploy and open http://localhost:1880/ui

Or use Grafana + InfluxDB for a production-grade dashboard with persistence.

Battery Life Analysis

With SLEEP_SEC = 300 (5 min), the duty cycle:

Estimated battery life (1000 mAh): ~107 hours ≈ 4.5 days

Increase sleep interval to 30 min → ~2.4 mA average → ~17 days.

Deliverables

1. Working node publishing readings every 5 minutes (or chosen interval)
2. Dashboard screenshot showing at least 1 hour of data
3. Sketch (.ino) with comments
4. Battery life estimate with your actual sleep interval