Electronic Notice Board Using 8051 Microcontroller

Introduction

An electronic notice board is a digital replacement for traditional notice boards used in institutions, offices, and public places. By using a microcontroller such as the 8051, we can create an efficient and programmable electronic notice board. This article explores the design, components, and implementation of an electronic notice board using the 8051 microcontroller.

Components Required

1. 8051 Microcontroller: The core processing unit for the project.

2. LED Display or LCD Module: To display the messages.

3. UART Interface: For serial communication.

4. Power Supply: To provide necessary voltage to the circuit.

5. Resistors, Capacitors, and other Passive Components: For building the supporting circuitry.

6. Programming Cable and Software: For uploading the code to the microcontroller.

Working Principle

The electronic notice board displays messages received via serial communication. The 8051 microcontroller processes these messages and updates the display accordingly. Users can send messages from a computer or other devices using a UART interface.

Circuit Design

1. Microcontroller (8051): The heart of the project, connected to the display module and the UART interface.

2. LED/LCD Display: Interfaced with the microcontroller to show the received messages.

3. UART Interface: Facilitates communication between the microcontroller and the input device (e.g., a computer).

4. Power Supply: Ensures stable voltage and current for the circuit components.

Circuit Diagram

Here's a simplified connection outline:

• 8051 Microcontroller Pins:

• P1: Connected to Data Lines of the Display.

• P2: Control Lines for the Display.

• RXD/TXD: Connected to the UART interface for receiving and transmitting data.

Software Implementation

1. Initializing UART: Set up the UART for serial communication.

2. Reading Data: Continuously check for incoming messages via UART.

3. Display Update: Update the LED/LCD display with the new message.

#include <reg51.h>

// Define pins for LCD

sbit RS = P2^0;

sbit RW = P2^1;

sbit EN = P2^2;

// Function prototypes

void UART_Init(void);

void UART_TxChar(char ch);

char UART_RxChar(void);

void LCD_Init(void);

void LCD_Cmd(unsigned char cmd);

void LCD_Char(unsigned char char_data);

void LCD_String(char *str);

void delay(unsigned int time);

void main(void) {

    char msg[32];

    int i = 0;

    UART_Init(); // Initialize UART

    LCD_Init();  // Initialize LCD

    while (1) {

        msg[i] = UART_RxChar(); // Read character from UART

        if (msg[i] == '\r') {   // Check for carriage return

            msg[i] = '\0';      // Null terminate the string

            i = 0;              // Reset index for next message

            LCD_Cmd(0x01);      // Clear the LCD

            LCD_String(msg);    // Display the message

        } else {

            i++;

        }

    }

}

// UART initialization function

void UART_Init(void) {

    TMOD = 0x20; // Timer 1 in mode 2

    TH1 = 0xFD;  // 9600 baud rate

    SCON = 0x50; // 8-bit data, 1 stop bit, 1 start bit

    TR1 = 1;     // Start timer

}

// UART transmit character function

void UART_TxChar(char ch) {

    SBUF = ch;  // Load character into buffer

    while (TI == 0); // Wait until transmission is complete

    TI = 0;     // Clear transmit interrupt flag

}

// UART receive character function

char UART_RxChar(void) {

    while (RI == 0); // Wait until data is received

    RI = 0; // Clear receive interrupt flag

    return SBUF; // Return received character

}

// LCD initialization function

void LCD_Init(void) {

    LCD_Cmd(0x38); // 2 lines, 5x7 matrix

    LCD_Cmd(0x0C); // Display ON, cursor OFF

    LCD_Cmd(0x06); // Increment cursor

    LCD_Cmd(0x01); // Clear display

    delay(10);     // Wait for initialization

}

// LCD command function

void LCD_Cmd(unsigned char cmd) {

    P1 = cmd; // Send command to data pins

    RS = 0;   // Command mode

    RW = 0;   // Write operation

    EN = 1;   // Enable pulse

    delay(1);

    EN = 0;

}

// LCD data function

void LCD_Char(unsigned char char_data) {

    P1 = char_data; // Send data to data pins

    RS = 1;   // Data mode

    RW = 0;   // Write operation

    EN = 1;   // Enable pulse

    delay(1);

    EN = 0;

}

// Function to display string on LCD

void LCD_String(char *str) {

    int i;

    for (i = 0; str[i] != '\0'; i++) {

        LCD_Char(str[i]);

    }

}

// Delay function

void delay(unsigned int time) {

    int i, j;

    for (i = 0; i < time; i++)

        for (j = 0; j < 1275; j++);

}

Conclusion

Building an electronic notice board using the 8051 microcontroller is a straightforward and practical project that introduces fundamental concepts of microcontroller programming and serial communication. This project can be expanded by adding features like wireless communication using Bluetooth or Wi-Fi modules and improving the display interface with more advanced graphical displays.

This guide should give you a good start on building your electronic notice board project. Happy coding!

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