🌡️ Arduino MQTT Display

Turn your Arduino Uno R4 WiFi into a smart temperature and humidity display using its built-in 12×8 LED Matrix!

✨ Features

• 📊 Real-time Display - Shows temperature, humidity, and clock on the Arduino Uno R4 WiFi's built-in 12×8 LED matrix
• 🔌 MQTT Integration - Subscribes to MQTT topics for live sensor data
• 📡 WiFi Connectivity - Connects to your home network automatically
• 🌙 Night Mode - Automatically switches to clock-only mode at nighttime.
• 💾 Persistent Storage - Saves last known values to EEPROM
• 🔄 Auto-recovery - Reconnects to WiFi and MQTT broker automatically
• ⏰ Network Time Sync - Displays accurate time using NTP
• 🎮 Serial Commands - Debug and control via serial interface
• 🧪 Simulation Mode - Test display with simulated values

🎯 What It Does

This project transforms your Arduino Uno R4 WiFi into a smart home display that:

1. Connects to your WiFi network
2. Subscribes to MQTT topics for temperature and humidity data
3. Displays sensor readings on the LED matrix in a rotating cycle:
   • Temperature (°C or °F)
   • Humidity (%)
   • Clock (HH:MM)
4. Persists the latest values so they survive power cycles
5. Publishes online/offline status to MQTT

🛠️ Hardware Requirements

• Arduino Uno R4 WiFi (with built-in 12×8 LED Matrix)
• USB cable for programming
• Power source (USB or external)

📚 Dependencies

These Arduino libraries are required (install via Library Manager):

• WiFiS3 - WiFi connectivity for Arduino Uno R4 WiFi
• ArduinoMqttClient - MQTT client
• Arduino_LED_Matrix - Control the built-in LED matrix
• ezTime - Network time synchronization
• EEPROM - Persistent storage

🚀 Getting Started

1. Clone the Repository

git clone https://github.com/elNino0916/ArduinoMQTTDisplay.git
cd ArduinoMQTTDisplay/MQTTDisplay

2. Configure Your Credentials

Create your configuration files from the examples:

cp examples/secrets.h.example secrets.h
cp examples/config.h.example config.h

3. Edit secrets.h

Add your WiFi and MQTT credentials:

const char WIFI_SSID[] = "YourWiFiName";
const char WIFI_PASS[] = "YourWiFiPassword";

const char MQTT_BROKER[] = "mqtt.example.com";
const int MQTT_PORT = 1883;

#define USE_MQTT_AUTH 1
const char MQTT_USER[] = "your_mqtt_username";
const char MQTT_PASS[] = "your_mqtt_password";

4. Edit config.h

Configure your MQTT topics and settings:

const char TOPIC_TEMP[] = "home/livingroom/temperature/state";
const char TOPIC_HUM[] = "home/livingroom/humidity/state";
const char TOPIC_STATUS[] = "home/display/status/state";
const char MQTT_CLIENT_ID[] = "uno-r4-matrix";

Adjust timing and behavior:

const unsigned long SHOW_MS = 8000;  // How long to show each screen (ms)
const unsigned long WIPE_MS = 450;   // Transition animation duration (ms)

5. Upload to Arduino

1. Open MQTTDisplay.ino in Arduino IDE
2. Select Board: "Arduino UNO R4 WiFi"
3. Select your Port
4. Click Upload

🎛️ Serial Commands

Connect via Serial Monitor (115200 baud) for debugging and control:

Command	Description
help	Show all available commands
status	Display current status and settings
show <temp|hum|clock|auto>	Force display mode or return to auto
sim temp <value|off>	Simulate temperature reading
sim hum <value|off>	Simulate humidity reading
sim both <temp> <hum>	Simulate both values
sim off	Disable all simulation
set <show_ms|ui_tick_ms> <value>	Adjust timing parameters
save settings	Save current settings to EEPROM
load settings	Load settings from EEPROM
factory reset	Reset to factory defaults
reboot	Restart the device

📊 MQTT Message Format

The display expects simple numeric values as MQTT payloads:

Temperature Topic (e.g., home/livingroom/temperature/state):

22.5

Humidity Topic (e.g., home/livingroom/humidity/state):

65.3

Values are validated:

• Temperature: -20°C to 60°C
• Humidity: 0% to 100%

🏗️ Project Structure

MQTTDisplay/
├── MQTTDisplay.ino          # Main Arduino sketch
├── config.h                 # Your configuration (gitignored)
├── secrets.h                # Your credentials (gitignored)
├── user_settings.h          # User-customizable settings
├── examples/
│   ├── config.h.example     # Configuration template
│   └── secrets.h.example    # Credentials template
└── src/
    ├── app_state.cpp/h      # Application state management
    ├── connection.cpp/h     # WiFi/MQTT connection handling
    ├── font.cpp/h           # Custom font for LED matrix
    ├── matrix_io.h          # LED matrix utilities
    ├── mqtt_client.cpp/h    # MQTT message handling
    ├── persist.cpp/h        # EEPROM persistence
    ├── schedule.cpp/h       # Night mode scheduling
    ├── time_service.cpp/h   # NTP time synchronization
    └── ui.cpp/h             # Display rendering logic

🌙 Night Mode

The display automatically dims or turns off during nighttime hours. Configure in schedule.cpp or use user_settings.h to force day/night mode for testing:

// #define FORCE_NIGHT_OFF  // Force display off
// #define FORCE_DAY_ON     // Force display always on

📝 License

This project is licensed under the MIT License - see the LICENSE file for details.

🙏 Acknowledgments

• Built specifically for the Arduino Uno R4 WiFi with its gorgeous built-in LED matrix
• Uses the excellent ezTime library for time synchronization
• MQTT support via ArduinoMqttClient