lcd interfacing with 8051 friendly

8051 HOW-TO GUIDE

Interfacing LCD with

8051

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Contents at a Glance

8051 Friendly Board ......................................................... 3

LCD (Liquid Crystal Display) .............................................. 3

Interfacing LCD ................................................................ 4

Interfacing 4 bit LCD with 8051 ........................................ 5

Pin Assignment with 8051 ................................................ 5

Circuit Diagram to Interface 4 bit LCD with 8051 .............. 6

Source Code .................................................................... 6

C Program to display a text in 4 bit LCD using 8051 ........... 7



8051 Friendly Board

The 8051 Friendly board is specifically designed to help

students to master the required skills in the area of

embedded systems. The kit is designed in such way that all

the possible features of the microcontroller will be easily

used by the students. The kit supports in system

programming (ISP) which is done through serial port.

NXPs 8051 (AT89V51RD2), 8051 friendly Kit is

proposed to smooth the progress of developing and

debugging of various designs encompassing of speed 8-bit

Microcontrollers.

LCD (Liquid Crystal Display)

Liquid Crystal Display also called as LCD is very helpful

in providing user interface as well as for debugging purpose.

A liquid crystal display (LCD) is a flat panel display that uses

the light modulating properties of liquid crystals (LCs). LCD

Modules can present textual information to user.



Interfacing LCD

Fig. 1 shows how to interface the LCD to

microcontroller. The 2x16 character LCD interface card with

supports both modes 4-bit and 8-bit interface, and also

facility to adjust contrast through trim pot. In 4-bit interface

7 lines needed to create 4-bit interface; 4 data bits (D0

D3), three control lines, address bit (RS), read/write bit

(R/W) and control signal (E).

Fig. 1 Interfacing 4 bit LCD to Microcontroller



2x16 CHAR LCD

1 3 20 16

Interfacing 4 bit LCD with 8051

We now want to display a text in 8051 Friendly Board

by using 4 bit LCD module.

The 8051 Friendly board has seven numbers of LCD

connections are needed to create 4-bit interface; connected

with 4 data bits (P0.4 P0.7, D4-D7), address bit (RS-P0.0),

read/write bit (R/W-P0.1) and control signal (E-P0.2) to

make LCD display.

Pin Assignment with 8051

LCD MODULE 8051 LINES 2x16 LCD Selection

CO

NTR

OL

RS P0.0

-LCD SELECT RW P0.1

E P0.2

DA

TA L

INES

D0-D3 NC

D4 P0.4

D5 P0.5

D6 P0.6

D7 P0.7

GN

D

VC

C

VEE

RS

R/W

E D4

D5

D6

D7

LED

+

LED

-

2 3 1

JP7



Circuit Diagram to Interface 4 bit LCD with 8051

Source Code

The Interfacing 4 bit LCD with 8051 program is very

simple and straight forward, which display a text in 2 X 16

LCD module using 4 data lines only. Some delay is occurring

when a single command / data is executed.



C Program to display a text in 4 bit LCD using 8051 ***************************************************************************************

Title : Program to 4 bit LCD display ***************************************************************************************

#include //Define 8051 Registers

#include //Define I/O Functions

#define DATA P0 //Define DATA to Port2

sbit RS = P0^0; //Register Select

sbit RW = P0^1; //LCD Read/Write

sbit lcd_e = P0^2; //LCD Enable

code unsigned char msg[] = (" PS.PRIMER-8051 "); //Display

code unsigned char msg1[] = (" 2x16 LCD DEMO ");

//----------------------------------

// LCD Functions

//----------------------------------

void lcd_init(void);

void lcd_cmd(unsigned char);

void lcd_display(unsigned char);

void DelayMs(int);

//----------------------------------

// LCD command Function

//----------------------------------

void lcd_cmd(unsigned char cmnd)

{

DATA = 0xf0&cmnd; //Masking lower 4

Bits

RS = 0; RW = 0;

lcd_e = 1;

DelayMs(35);

lcd_e = 0;

DATA = cmnd*16; //Masking lower 4

RS = 0; RW = 0;

lcd_e = 1;



DelayMs(35);

lcd_e = 0;

}

//----------------------------------

// LCD Data Function

//----------------------------------

void lcd_display(unsigned char dat)

{

DATA = 0xf0&dat; //Masking lower 4

RS = 1; RW = 0;

lcd_e = 1;

DelayMs(35);

lcd_e = 0;

DATA = dat*16; //Masking lower 4

RS = 1; RW = 0;

lcd_e = 1;

DelayMs(35);

lcd_e = 0;

}

//----------------------------------

// LCD Delay Function

//----------------------------------

void DelayMs(int k)

{

unsigned int a;

for(a=0;a



lcd_cmd(0x28); //2x16 Character 5x7

DelayMs(15); //matrix LCD,4-bit format

lcd_cmd(0x0c);

DelayMs(15);

lcd_cmd(0x06); //Shift

DelayMs(15);

lcd_cmd(0x01);

DelayMs(15);

//-------------------------------------------

// First Line Message Display

//-------------------------------------------

lcd_cmd(0x80);

DelayMs(35);

i=0;

while(msg[i]!='\0')

{

lcd_display(msg[i]);

i++;

}

DelayMs(50);

//-------------------------------------------

// Second Line Message Display

//-------------------------------------------

lcd_cmd(0xc0); //Second

DelayMs(35);

i=0;

while(msg1[i]!='\0')

{

lcd_display(msg1[i]);

i++;

}

DelayMs(50);

}



//----------------------------------

// LCD Main Program

//----------------------------------

void main(void)

{

P0 = 0;

lcd_init(); //LCD Initialization

DelayMs(1);

DelayMs(1);

while(1); //Loop Forever

}



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