Smartphone Typogrphy: Bluetooth Notice Board 16x2

A standard LCD display cannot change its text dynamically without the programmer writing new C++ code on a laptop. The Bluetooth Wireless Notice Board using LCD transforms the static screen into a live IoT message receiver. By connecting an HC-05 Radio to a smartphone App, you can wirelessly blast emergency warnings (Evacuate Area!) or daily reminders entirely across a building structure.

Buffer Parsing and Accumulation

The biggest error made by beginners is assuming Serial.read() grabs a whole word. It grabs EXACTLY ONE char ('E', 'v', 'a').

1. The SoftwareSerial Bus: The HC-05 is wired to Pin 10 (RX), Pin 11 (TX).
2. The user types ROOM LOCKED\n on their phone.
3. The C++ code utilizes the while() buffer loop:

String inData = "";
while (bluetooth.available() > 0) {
  char incoming = bluetooth.read();
  if (incoming == '\n') { // The absolute termination trigger!
    processData(inData); 
    inData = ""; // Clear buffer!
    break; 
  }
  inData += incoming; 
  delay(3); // CRITICAL: Stop the Arduino from checking the buffer faster than Bluetooth can transmit!
}

Screen Pagination Math (16 Characters)

The LCD screen is agonizingly small. If the text string is WELCOME TO THE MEETING ROOM EARLY, it will completely crash off the right edge of the LCD!

• The Uno must physically calculate if inData.length() > 16.
• If the string is massive, the C++ code must break it into chunks!
• lcd.setCursor(0, 0); lcd.print(inData.substring(0, 16)); (First Line)
• lcd.setCursor(0, 1); lcd.print(inData.substring(16, 32)); (Second Line)
• A physical buzzer acts as a notification layer, sounding a piercing "BEEP-BEEP!" to alert the room the moment a brand new message arrives!

Wireless Output Requisites

• Arduino Uno/Nano (Standard architecture).
• HC-05 or HC-06 Bluetooth Slave Module (Requires a physical 1k/2k Resistor Voltage Divider stepping down the Uno's 5V TX pin so it doesn't fry the delicate 3.3V HC-05 RX logic!).
• 16x2 I2C Character Display Module (I2C saves 10 wires!).
• Standard Active Piezo Buzzer as the auditory notification system.