LCD interfacing to 8051
In recent years LCD
is finding widespread use replacing LEDs
1. The
declining prices of LCD
2.The ability
to display numbers, characters, and
graphics
3.Incorporation
of a refreshing controller into the LCD, thereby relieving the CPU of
the task
of refreshing the LCD
4.Ease of
programming for characters and Graphics
LCD pin description
The LCD has
16 pins . The function of each pin is given below:
Vcc, Vss and Vee
While Vcc and Vss provides +5v and ground
,respectively, Vee is used to control the contrast of LCD.
RS(register select)
There are two very important registers inside the
LCD. The RS pin is used to select them.If RS =0, the instruction command code
register is selected allowing the user to send a command such as clear display
etc. If RS=1 , data register is selected ,allowing the user to display data on
LCD.
R/W(read/write)
This pin is used to select the read and write
operation of LCD.
E(enable)
This pin is used to latch the data into the LCD
presented on data pins. A high to low pulse must be applied to latch the data.
D0-D7
These are the data pins of LCD,used to send the data
and command to LCD.
Led+,Led-
These two pins are used to provide +5v and ground to
the backlight LED.
Pin Description
1. Ground
2. +5v
power supply
3. Supply to control contrast
4. To select register(RS)
5. To
select read or write
operation(R/W)
6. enable pin(E)
7-14. 8 bit
data bus
15. Led+
16. Led-
Commands for LCD
Code(hex) Command to LCD
instruction register
1 Clear display screen
2 Return home
4 Shift cursor to left
6 Shift cursor to right
5 Shift display right
7 Shift display left
8 Display off, cursor off
A Display off ,
cursor on
C Display on, cursor off
E Display
on, cursor blinking
F Display on ,cursor blinking
10 Shift cursor position to left
14 Shift cursor position to right
18 Shift the entire display to left
1C Shift the entire display to right
80 Force cursor to beginning of 1s line
C0 Force cursor to beginning of 2n line
38 2 lines and 5x7 matrix
PROGRAM TO DISPLAY CHARACTERS ON LCD
P1 is connected to data pins of LCD
P3.1 is connected to RS pin of LCD
P3.2 is connected to R/W pin of LCD
P3.0 is connected to E pin of LCD
#include <reg51.h>
void MSDelay(unsigned int );
void lcdcmd(unsigned char);
void lcddata(unsigned char);
sbit rs = P3^1;
sbit rw = P3^2;
sbit en = P3^0;
void main()
{
lcdcmd(0x38);
lcdcmd(0x0E);
lcdcmd(0x01);
lcdcmd(0x06);
lcdcmd(0x86);
lcddata(‘M’);
lcddata(‘S’);
lcddata(‘K’);
}
void lcdcmd(unsigned char value)
{
P1 = value;
rs = 0;
rw = 0;
en = 1;
MSDelay(1);
en = 0;
}
void lcddata(unsigned char value)
{
P1 = value;
rs = 1;
rw = 0;
en = 1;
MSDelay(1);
en = 0;
}
void MSDelay(unsigned int itime)
{
unsigned int i, j;
for(i=0;i<itime;i++)
for(j=0;j<1275;j++);
}
PROGRAM TO DISPLAY
STRING ON LCD
#include<reg51.h>
void delay(unsigned int );
void lcdcmd(unsigned char);
void lcddata(unsigned char);
sbit rs = P3^1;
sbit rw = P3^2;
sbit en = P3^0;
void main ()
{
unsigned char str[]="MANPREET SINGH AKALI";
unsigned char i=0;
unsigned char str[]="MANPREET SINGH AKALI";
unsigned char i=0;
P2=0x00;
P1=0x00;
P3=0x00;
while(1)
{
lcdcmd(0x38);
delay(50);
lcdcmd(0x0E);
delay(50);
lcdcmd(0x01);
delay(50);
lcdcmd(0x80);
delay(50);
while
(str[i]!='\0'){
lcddata(str[i]);
if(i==15)
{
lcdcmd(0x0C0);
delay(50);
}
delay(1500);
i++;
}
delay(5000);
}
}
void
lcdcmd(unsigned char value)
{
P1=
value;
rs =
0;
rw = 0;
en = 1;
delay(1);
en = 0;
return;
}
void lcddata(unsigned char value)
{
P1=value;
rs=1;
rw=0;
en=1;
delay(1);
en=0;
}
void delay(unsigned int time)
{
unsigned
int i,j;
for(i=0;i<time;i++)
for(j=0;j<50;j++);
}
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