Sensor IoT Dashboard

End-to-End for monitoring IoT sensors via MQTT, built with Jetpack Compose and modern Android architecture.

Demo

Real-time temperature and humidity monitoring with connection status

Hardware & Communication

ESP32 with DHT11 sensor publishing data via MQTT

Project Structure

• /firmware - ESP32 sensor firmware (PlatformIO/C++)
• /app - Android monitoring application (Kotlin/Compose)

Architecture

ESP32 + DHT11 Sensor
    ↓ WiFi
MQTT Broker (test.mosquitto.org)
    ↓ Subscribe
Android App (Jetpack Compose)
    ↓ StateFlow
UI Layer

Features

• Real-time temperature and humidity monitoring from DHT11 sensor
• MQTT communication via public broker (test.mosquitto.org)
• Connection status indicators
• Manual sensor connect/disconnect controls
• Timestamp tracking for last update

Tech Stack

Firmware

• Platform: PlatformIO
• Board: ESP32 (ESP32-DevKit)
• Language: C++ (Arduino framework)
• Protocol: MQTT (Eclipse Paho)
• Sensor: DHT11 (temperature/humidity)

Android

• Language: Kotlin
• UI: Jetpack Compose, Material 3
• Architecture: MVVM with clean separation
• DI: Hilt (Dagger)
• Async: Coroutines, Flow, StateFlow
• IoT: MQTT client (Eclipse Paho Android)

Quick Start

1. ESP32 Firmware

cd firmware

# Configure WiFi credentials
cp src/credentials.h.example src/credentials.h
# Edit credentials.h with your WiFi SSID and password

# Build and upload (requires PlatformIO)
pio run --target upload

# Monitor serial output
pio device monitor

See firmware/README.md for detailed setup instructions.

2. Android App

# Build and run
./gradlew installDebug

# Or open in Android Studio

Hardware Setup

Components:

• ESP32 development board
• DHT11 temperature & humidity sensor
• Breadboard and jumper wires

Wiring:

DHT11 VCC  → ESP32 3.3V
DHT11 Data → ESP32 GPIO4
DHT11 GND  → ESP32 GND

MQTT Configuration:

• Broker: test.mosquitto.org:1883
• Topic: parissa/sensors
• Message format: {"temperature": 23.5, "humidity": 65.0}

Development

Prerequisites

Firmware:

• VS Code with PlatformIO IDE
• ESP32 USB drivers (CH340/CP2102)

Android:

• Android Studio Hedgehog or later
• JDK 11+
• Android SDK API 24+

Project Architecture

Android (MVVM):

UI Layer (Compose)
    ↓ observes
ViewModel (Hilt injected)
    ↓ collects
Repository Layer
    ↓ delegates to
MqttDataSource (callbackFlow)

Learning Objectives

This project demonstrates:

1. Modern Android Development

   • Jetpack Compose for declarative UI
   • MVVM architecture with proper separation
   • Hilt for dependency injection
   • Coroutines & Flow for reactive programming

2. IoT Integration

   • MQTT protocol implementation
   • Real-time data streaming
   • Connection state management
   • Hardware-software integration

3. Professional Tooling

   • PlatformIO for embedded development
   • Git-based credential management
   • Clean project structure
   • Production-ready patterns

Author

Parissa Kalaee
Senior Embedded Systems & Android Engineer
LinkedIn