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Liquid Crystal DisplayLiquid Crystal DisplayAn LCD is electronically

modulated optical device shaped into a thin, flat panel made up of any number of color or monochrome pixels filled with liquid crystals.

It is often used in battery - powered electronic devices because it requires very small amounts of electric power

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Liquid Crystal DisplayLiquid Crystal DisplayLCDs have become a cheap and easy way to

get text display for an embedded system.Common displays are set up as 16 to 20

characters by 1 to 4 lines. The most commonly used ALPHANUMERIC

displays are 1x16 (Single Line & 16 characters), 2x16 (Double Line & 16 character per line) & 4x20 (four lines & Twenty characters per line). 

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An Example

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UNDERSTANDING LCD

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Dot MatrixDot MatrixA 5X7 display consists of

a matrix of lights or mechanical indicators arranged in a rectangular configuration.

By switching on or off selected lights, text or graphics can be displayed.

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Dot Matrix ExampleDot Matrix Example

7

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Pin Out

15 – VCC (Backlight) , 16- GND

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Pinout

Pin-Description 8 data pins D7:D0: Bi-directional data/command pins. Alphanumeric characters are sent in ASCII format.

  RS:  Register Select RS = 0 -> Command Register is selected RS = 1 -> Data Register is selected

  R/W: Read or Write 0 -> Write 1 -> Read

  E: Enable (Latch data) Used to latch the data present on the data pins. A high-to-low edge is needed to latch the data.

  VEE : contrast control

 

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Important Note:

For Contrast setting a 10K pot should be used as shown in the figure.

Two types of data is given to the LCD data to be displayed, command or special instruction.

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Display Data Ram (DDRAM)

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For a 2x16 LCD the DDRAM address for first line is from 80h to 8FH & for second line is C0H to CFH.

So if we want to display 'H' on the 7th position of the first line then we will write it at location 87h.

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LCD Commands Table

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INTERFACING LCD TO 8051

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Project Assignment 4

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Embedded C Program#include<reg52.h>sfr ldata = 0x90;sbit rs = P2^0;sbit rw = P2^1;sbit en = P2^2;void lcdcmd(unsigned char

value);void lcddata(unsigned char

value);void msdelay(unsigned int

itime);

void main(){lcdcmd(0x38);msdelay(150);lcdcmd(0x0E);msdelay(150);lcdcmd(0x01);msdelay(150);lcdcmd(0x07);msdelay(150);lcdcmd(0x8B);msdelay(150);

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lcddata('C');msdelay(150);lcddata('H');msdelay(150);lcddata('I');msdelay(150);lcddata('P');msdelay(150);lcddata('A');msdelay(150);

lcddata('D');msdelay(150);lcddata('R');msdelay(150);lcddata('O');msdelay(150);lcddata('I');msdelay(150);lcddata('T');msdelay(150);lcddata('S');}

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void lcdcmd(unsigned char value)

{ldata=value;rs=0;rw=0;en=1;msdelay(1);en=0;return;} void lcddata(unsigned char

value){ldata=value;

rs=1;rw=0;en=1;msdelay(1);en=0;return;}void msdelay(unsigned int

itime){unsigned int i,j;for(i=0;i<itime;i++)for(j=0;j<1275;j++);}

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THANKS

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