IoT Developer Skill

I help you build IoT applications, connect sensors and devices, and create smart home/industrial IoT solutions.

What I Do

Device Integration:

• Microcontroller programming (Arduino, ESP32)
• Sensor reading and data collection
• Actuator control (motors, LEDs, relays)
• Hardware interfacing

Communication:

• MQTT messaging
• WebSocket connections
• REST API integration
• Bluetooth/WiFi connectivity

IoT Platforms:

• Real-time dashboards
• Device management
• Data logging
• Alerts and automation

MQTT Basics (Web Client)

npm install mqtt

// lib/mqtt-client.ts
import mqtt from 'mqtt'

export class MQTTClient {
  private client: mqtt.MqttClient

  constructor(brokerUrl: string) {
    this.client = mqtt.connect(brokerUrl, {
      clientId: `web_${Math.random().toString(16).slice(3)}`,
      clean: true,
      connectTimeout: 4000
    })

    this.client.on('connect', () => {
      console.log('MQTT connected')
    })

    this.client.on('error', error => {
      console.error('MQTT error:', error)
    })
  }

  subscribe(topic: string, callback: (message: string) => void) {
    this.client.subscribe(topic, err => {
      if (err) console.error('Subscribe error:', err)
    })

    this.client.on('message', (receivedTopic, message) => {
      if (receivedTopic === topic) {
        callback(message.toString())
      }
    })
  }

  publish(topic: string, message: string) {
    this.client.publish(topic, message)
  }

  disconnect() {
    this.client.end()
  }
}

Usage:

'use client'
import { useEffect, useState } from 'react'
import { MQTTClient } from '@/lib/mqtt-client'

export function TemperatureDashboard() {
  const [temperature, setTemperature] = useState(0)
  const [humidity, setHumidity] = useState(0)

  useEffect(() => {
    const mqtt = new MQTTClient('ws://broker.hivemq.com:8000/mqtt')

    mqtt.subscribe('home/temperature', (msg) => {
      setTemperature(parseFloat(msg))
    })

    mqtt.subscribe('home/humidity', (msg) => {
      setHumidity(parseFloat(msg))
    })

    return () => mqtt.disconnect()
  }, [])

  return (
    <div className="grid grid-cols-2 gap-4">
      <div className="p-6 bg-white rounded-lg shadow">
        <h3 className="text-gray-600">Temperature</h3>
        <p className="text-4xl font-bold">{temperature}°C</p>
      </div>

      <div className="p-6 bg-white rounded-lg shadow">
        <h3 className="text-gray-600">Humidity</h3>
        <p className="text-4xl font-bold">{humidity}%</p>
      </div>
    </div>
  )
}

Arduino/ESP32 Code

Temperature Sensor (DHT22)

// ESP32 + DHT22 Temperature/Humidity Sensor
#include <WiFi.h>
#include <PubSubClient.h>
#include <DHT.h>

#define DHTPIN 4
#define DHTTYPE DHT22

const char* ssid = "YOUR_WIFI_SSID";
const char* password = "YOUR_WIFI_PASSWORD";
const char* mqtt_server = "broker.hivemq.com";

WiFiClient espClient;
PubSubClient client(espClient);
DHT dht(DHTPIN, DHTTYPE);

void setup() {
  Serial.begin(115200);
  dht.begin();

  // Connect to WiFi
  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println("WiFi connected");

  // Connect to MQTT