LCD Interfacing with 8051 Microcontroller

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Power Point presentations , Simulators are used in the demostrations of the code

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D714D613D512D411D310D29D18D07

E6RW5RS4

VSS1 VDD2 VEE3

LCD Interfacing with 8051 Microcontroller

TVLNH Prasad

Asst. Professor Dept. Of Physics & Electronics Bhavan’s Vivekananda College, Sainikpuri.

B V C Dept. Of Physics and Electronics 2 Objectives

List of reasons for considering LCD

Functions of the pins of a typical LCD

Command codes for programming LCD

interface LCD to the 8051

Programming techniques

B V C Dept. Of Physics and Electronics 3 Introduction

Alphanumeric displays are used in a wide range of applications, including palmtop computers, word processors, photocopiers, point of sale terminals, medical instruments, cellular phones, etc.

The 16 x 2 intelligent alphanumeric dot matrix display is capable of displaying 224 different characters and symbols. (note these symbols can vary between brand of LCD used).

(LCD is finding widespread

use replacing

LEDs)

The declining prices of LCD

The ability to display numbers, characters, and graphics

Incorporation of a refreshing controller into the LCD, thereby relieving the CPU of the task of refreshing the LCD

Ease of programming for characters and graphics

(Various LCDs)

D714D613D512D411D310D29D18D07

E6RW5RS4

VSS1 VDD2 VEE3

LCD1

LM020L

16 X 1 ALPHA NUMERIC

D714D613D512D411D310D29D18D07

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VSS1 VDD2 VEE3 LCD2 LM016L

D714D613D512D411D310D29D18D07

E6RW5RS4

(Various LCDs)

D714D613D512D411D310D29D18D07

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VSS1 VDD2 VEE3

LCD4

LM041L

CE15

RD5C/D4

VSS1 VDD2 VO3 WR6 D07 FS119

D18 D29 D310 D411 D512 D613 D714 RST16 MD218 HALT20

VEE17

LM3228

128 x 64 GRAPHICAL LCD

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Power Point presentations , Simulators are used in the demostrations of the code

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B V C Dept. Of Physics and Electronics 7 LCD

pin description

Pin

No Name I / O Function

1 Vss -- Ground (0V)

2 VDD -- Supply voltage; 5V (4.7V – 5.3V) 3 V_EE -- Contrast adjustment; through a

variable resistor

4 Register Select I RS = 0 for Command register RS = 1 for Data register

5 Read/write I Low to write to the register; High to read from the register

6 Enable I / O Sends data to data pins when a high to low pulse is given

7 DB0 I / O

8-bit data pins

8 DB1 I / O

9 DB2 I / O

10 DB3 I / O

11 DB4 I / O

12 DB5 I / O

13 DB6 I / O

14 DB7 I / O

15 Led+ -- Backlight VCC(5V)

16 Led- -- Backlight Ground (0V)

D714D613D512D411D310D29D18D07

E6RW5RS4

VSS1VDD2VEE3 LCD2 LM016L

B V C Dept. Of Physics and Electronics 8 LCD pin

description

There are two very important registers inside LCD they are

Instruction Command code register and Data register

The RS pin is used for their selection If RS = 0

Instruction Command code register is selected

If RS = 1 The data register is selected RS (Register Select)

description

Input allows the user to write information to the LCD or read information from it.

R/ W = 1 when reading R/W = 0 when writing R/ W , read / write

description

A high – to – low pulse must be applied to this pin in order to latch the data present on data pins.

This pulse width must be a min of 450ns wise.

E , Enable

Command codes

Code (Hex) Command to LCD Instruction Register 01 Clear display screen

02 Return home

04 Decrement cursor (shift cursor to left) 06 Increment cursor (shift cursor to right) 05 Shift display right

07 Shift display left 08 Display off, cursor off 0A Display off, cursor on 0C Display on, cursor off 0E Display on, cursor blinking 0F Display on, cursor blinking 10 Shift cursor position to left 14 Shift cursor position to right 18 Shift the entire display to the left 1C Shift the entire display to the right 80 Force cursor to beginning to 1st line C0 Force cursor to beginning to 2nd line 38 2 lines and 5x7 matrix

Command codes

Code (Hex)

Command to LCD Instruction Register

38

2 lines and 5x7 matrix

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Power Point presentations , Simulators are used in the demostrations of the code

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Timing diagram and

Program COMNWRT: ;send command to LCD MOV P1,A ;copy reg A to port 1 CLR P2.0 ;RS=0 for command CLR P2.1 ;R/W=0 for write SETB P2.2 ;E=1 for high pulse LCALL DELAY ;give LCD some time CLR P2.2 ;E=0 for H-to-L pulse RET

P2.0 P2.1 P2.2

B V C Dept. Of Physics and Electronics 14 Circuit

diagram

0 1 2 3 5 4 6 7

01234567D714D613D512D411D310D29D18D07

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XTAL2 18

XTAL1 19

30 ALE 31 EA 29 PSEN

9 RST

P0.0/AD0 39 P0.1/AD1 38 P0.2/AD2 37 P0.3/AD3 36 P0.4/AD4 35 P0.5/AD5 34 P0.6/AD6 33 P0.7/AD7 32

P2.7/A15 28 P2.0/A8 21 P2.1/A9 22 P2.2/A10 23 P2.3/A11 24 P2.4/A12 25 P2.5/A13 26 P2.6/A14 27

1 P1.0 2 P1.1 3 P1.2 4 P1.3 5 P1.4 6 P1.5 7 P1.6 8 P1.7

P3.0/RXD 10 P3.1/TXD 11 P3.2/INT0 12 P3.3/INT1 13 P3.4/T0 14

P3.7/RD 17 P3.6/WRP3.5/T1 1615 U1

80C51

RV1(1) 10K

LCD Interfacing with 8051 Microcontroller

TVLNH Prasad

Dept. Of Physics & Electronics Bhavan’s Vivekananda College, Sainikpuri.

Asst. Professor

B V C Dept. Of Physics and Electronics 15 Programming

LCD (Displaying

Single characters)

;To send any of the commands to the LCD, make pin RS=0. For data,

;make RS=1. Then send a high-to-low pulse to the E pin to enable

;the internal latch of the LCD. This is shown in the code below.

;calls a time delay before sending next data/command

;P1.0-P1.7 are connected to LCD data pins D0-D7

;P2.0 is connected to RS pin of LCD

;P2.1 is connected to R/W pin of LCD

;P2.2 is connected to E pin of LCD

ORG 0H

MOV A,#38H ;initialisation of LCD 2 LINES, 5X7 MATRIX LCALL COMNWRT ;call command subroutine

LCALL DELAY ;give LCD some time MOV A,#0EH ;display on, cursor on LCALL COMNWRT ;call command subroutine LCALL DELAY ;give LCD some time MOV A,#01 ;clear LCD

LCALL COMNWRT ;call command subroutine LCALL DELAY ;give LCD some time MOV A,#06H ;shift cursor right

Contiuation …..

LCD (Displaying

Single characters)

(Delay Program)

LCALL COMNWRT ;call command subroutine LCALL DELAY ;give LCD some time MOV A,#84H ;cursor at line 1, pos. 4 LCALL COMNWRT ;call command subroutine LCALL DELAY ;give LCD some time MOV A,#’B’ ;display letter B LCALL DATAWRT ;call display subroutine LCALL DELAY ;give LCD some time MOV A,#’V’ ;display letter V LCALL DATAWRT

LCALL DELAY

MOV A,#’C’ ;display letter C LCALL DATAWRT

LCALL DELAY

AGAIN: SJMP AGAIN ;stay here

DELAY: MOV R3,#50 ; R3 = 50 HERE2: MOV R4,#255 ;R4 = 255

HERE: DJNZ R4,HERE ;stay until R4 becomes 0 DJNZ R3,HERE2

RET Contiuation …..

LCD (Subroutines)

DATAWRT: ;write data to LCD MOV P1,A ;copy reg A to port 1 SETB P2.0 ;RS=1 for data CLR P2.1 ;R/W=0 for write SETB P2.2 ;E=1 for high pulse LCALL DELAY ;give LCD some time CLR P2.2 ;E=0 for H-to-L pulse

RET

COMNWRT: ;send command to LCD MOV P1,A ;copy reg A to port 1 CLR P2.0 ;RS=0 for command CLR P2.1 ;R/W=0 for write SETB P2.2 ;E=1 for high pulse LCALL DELAY ;give LCD some time CLR P2.2 ;E=0 for H-to-L pulse RET

END

LCD (Output)

0 1 2 3 5 4 6 7

01234567D714D613D512D411D310D29D18D07

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XTAL2 18

XTAL1 19

9 RST

1 P1.0 2 P1.1 3 P1.2 4 P1.3 5 P1.4 6 P1.5 7 P1.6 8 P1.7

P3.0/RXD 10 P3.1/TXD 11 P3.2/INT0 12 P3.3/INT1 13 P3.4/T0 14 P3.7/RD 17 P3.6/WRP3.5/T1 1615 U1

80C51

RV1(1) 10K

LCD Interfacing with 8051 Microcontroller TVLNH Prasad

Asst. Professor

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Power Point presentations , Simulators are used in the demostrations of the code

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B V C Dept. Of Physics and Electronics 19 Sending

information to LCD using

MOVC instruction

ORG 300H

MYCOM: DB 38H,0EH,01,06,84H,0 ; commands and null MYDATA: DB “Hello”,0

ORG 00h

AGAIN: MOV DPTR,#MYCOM

C1: CLR A

MOVC A,@A+DPTR

LCALL COMNWRT ;call command subroutine LCALL DELAY ;give LCD some time INC DPTR

JZ SEND_DAT SJMP C1

SEND_DAT: MOV DPTR,#MYDATA

D1: CLR A

MOVC A,@A+DPTR

LCALL DATAWRT ;call command subroutine LCALL DELAY ;give LCD some time INC DPTR

JZ AGAIN SJMP D1

SJMP AGAIN ;stay here

B V C Dept. Of Physics and Electronics 20 Sending

information to LCD using

MOVC instruction

0 1 2 3 5 4 6 7

01234567D714D613D512D411D310D29D18D07

E6RW5RS4

XTAL2 18

XTAL1 19

9 RST

1 P1.0 2 P1.1 3 P1.2 4 P1.3 5 P1.4 6 P1.5 7 P1.6 8 P1.7

P3.0/RXD 10 P3.1/TXD 11 P3.2/INT0 12 P3.3/INT1 13 P3.4/T0 14

P3.7/RD 17 P3.6/WRP3.5/T1 1615 U1

80C51

RV1(1) 10K

LCD Interfacing with 8051 Microcontroller TVLNH Prasad

Asst. Professor

B V C Dept. Of Physics and Electronics 21 Outcome

We learned how to interface real – world devices such as LCD

We described the operation modes of LCD How to program the LCD by sending data or

command to it via its interface to the 8051 We got an idea how to work with Alpha

numeric LCD

B V C Dept. Of Physics and Electronics 22

Thank You

Simulators used in this presentation are

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Jubin Mitra 8085 simulator for the lab experiments demonstrations…

Dia0.97.2 is used during the classes which is a program for drawing structured

diagrams….

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https://vlab.amrita.edu/index.php

Physics experiments in this tool are used for practice sessions …

http://www.olabs.edu.in/?pg=topMenu&id=40

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This is a free version, which contains ads. The full documentation is available at ecstudiosystems.com/help

Electric Circuit Studio is a set of tools used for building electronic circuits, SPICE simulation, and calculation of circuits. These tools are complemented by the information center containing resources, connector pinouts and short interactive book explaining basic electrical theorems, laws and circuits. It is a useful application for all electronics hobbyists, students, or other people

with an interest in electronics.

https://phet.colorado.edu/

this simulator is having windows as well as android versions

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https://www.falstad.com/circuit/

https://circuitverse.org/simulator http://eleceng.dit.ie/dsp/elab/

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Tinkercad.com

Deeds Digital Circuit Simulator

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