IoT and Cloud Integration

MQTT Protocol

MQTT (Message Queue Telemetry Transport) is the standard protocol for IoT devices. Lightweight, publish/subscribe model, works over TCP. Devices publish messages to topics (home/pi/temperature). Other devices or servers subscribe to topics and receive messages. A broker (e.g., Mosquitto, HiveMQ, AWS IoT) routes messages between publishers and subscribers. The Pi publishes sensor data; your phone subscribes to receive it.

Node-RED for Visual Automation

Node-RED is a visual programming tool that runs on the Pi (or in the cloud). Connect sensor inputs to processing logic to outputs using a drag-and-drop interface. Built-in nodes: HTTP, MQTT, email, Telegram, InfluxDB, and hundreds of third-party nodes. Build automation flows without writing code: 'when temperature > 30, send Telegram message and turn on fan GPIO'. Install with: bash <(curl -sL https://raw.githubusercontent.com/node-red/linux-installers/master/deb/update-nodejs-and-nodered)

Cloud Dashboards

Grafana + InfluxDB is the standard IoT time-series stack. InfluxDB stores time-series sensor data. Grafana visualizes it with professional dashboards — heatmaps, gauges, graphs, alerts. Both run on the Pi for local use or on a cloud VM for remote access. Alternatively, use Adafruit IO (free tier: 30 data points/minute, 5 feeds) for a hosted solution that requires zero server management.

#!/usr/bin/env python3
# MQTT publisher: Pi sends sensor data to a broker
# pip3 install paho-mqtt adafruit-circuitpython-dht

import json, time, board, adafruit_dht
import paho.mqtt.client as mqtt

# Configure
BROKER  = 'localhost'    # or 'broker.hivemq.com' for public test broker
PORT    = 1883
TOPIC   = 'home/pi/sensors'
DEVICE  = 'pi-living-room'

client = mqtt.Client(client_id=DEVICE)
client.connect(BROKER, PORT, keepalive=60)
client.loop_start()

dht = adafruit_dht.DHT22(board.D4, use_pulseio=False)

print(f"Publishing to {BROKER}:{PORT}/{TOPIC}")
try:
    while True:
        try:
            payload = json.dumps({
                'device':   DEVICE,
                'ts':       time.time(),
                'temp_c':   round(dht.temperature, 1),
                'humidity': round(dht.humidity, 1),
            })
            result = client.publish(TOPIC, payload, qos=1)
            result.wait_for_publish()
            print(f"Published: {payload}")
        except RuntimeError:
            print("DHT read error, retrying...")
        time.sleep(30)
except KeyboardInterrupt:
    client.loop_stop()
    client.disconnect()
    dht.exit()
    print("Disconnected.")