Lcd interfacing using 8051 and assembly language programming

1. Dr. Vikas Dongre
HOD Electronics
Government Polytechnic Washim
Maharashtra, India
dongrevj1@gmail.com
With KEIL program and
Proteus Simulation

2. LCD is finding widespread use replacing LEDs
􀂾 The declining prices of LCD, descent looking, less power consumption
􀂾 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
Seven Segment Display
Liquid Crystal Display (LCD)
Liquid Crystal Display

4. LCD Block DiagramLCD Char 5x7 Matrix
16x2 LCD DISPLAY

5. Interfacing Diagram

6. Pin Symbol I/O Description
1 Vss - Ground
2 Vdd - +5V Power Supply
3 Vee - Contrast control power supply
4 RS Register select
RS=0 Command register
RS=1 Data register
5 R/W I R- Write/ W-Read
6 E I Enable
7-14 DB0-DB7 I/O Data Bus
16x2 LCD Display

7. Working of LCD Display controller
1.Command Register: Controls the working of LCD Controller
2.Data Register: Used to store the data to be displayed on LCD
3.Alphanumeric and graphic Character set memory for various
languages

8. 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
0 80 81 82 83 84 85 86 87 88 89 8A 8B 8C 8D 8E 8F
1 C0 C1 C2 C3 C4 C5 C6 C7 C8 C9 CA CB CC CD CE CF
16x2 LCD DISPLAY ADDRESSES
2 ROWS
16 COLUMNS

9. Co
de
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
Co
de
Command to LCD Instruction
Register
0E 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

10. Algorithm
Start
Initialize LCD by providing various
commands to Control register
Send data to be
displayed on Data
register byte by byte
Stop

11. COMNWRT: ;send command to LCD
MOV P0, A ;copy reg A to port 0
CLR RS ;RS=0 for command Register
CLR RW ;R/W=0 for write
SETB E ;E=1 for high pulse
CLR E ;E=0 for H-to-L pulse
ACALL DELAY ;give LCD some time
RET
Subroutine for
Writing in Command Register
DATAWRT: ;send command to LCD
MOV P0,A ;copy reg A to port 1
SETB RS ;RS=1 for Data Register
CLR RW ;R/W=0 for write
SETB E ;E=1 for high pulse
CLR E ;E=0 for H-to-L pulse
ACALL DELAY ;give LCD some time
RET
Subroutine for
Writing in Data Register

12. ORG 0000
MOV A,#38H ;INIT. LCD 2 LINES, 5X7 MATRIX
ACALL COMNWRT ;call command subroutine
MOV A,#0EH ;display on, cursor on
ACALL COMNWRT ;call command subroutine
MOV A,#01 ;clear LCD
ACALL COMNWRT ;call command subroutine
MOV A,#06H ;shift cursor right
ACALL COMNWRT ;call command subroutine
MOV A,#86H ;cursor at line 1, pos. 6
ACALL COMNWRT ;call command subroutine
Program to display the word “WORLD” on 16x2 LCD Display
Initialize Control register

13. MOV A,#“W" ;display letter W
ACALL DATAWRT ;call display subroutine
MOV A,#“O" ;display letter O
ACALL DATAWRT ;call display subroutine
MOV A,#“R" ;display letter R
ACALL DATAWRT ;call display subroutine
MOV A,#“L" ;display L
ACALL DATAWRT ;call display subroutine
MOV A,#“D" ;display D
ACALL DATAWRT ;call display subroutine
Send data to be
displayed on Data
register

14. COMNWRT: ;send command to LCD
MOV P0,A ;copy reg A to port 1
CLR P1.0 ;RS=0 for command
CLR P1.1 ;R/W=0 for write
SETB P1.2 ;E=1 for high pulse
CLR P1.2 ;E=0 for H-to-L pulse
ACALL DELAY ;give LCD some time
RET
COMMAND WORD SUBROUTINE

15. DATAWRT: ;write data to LCD
MOV P0,A ;copy reg A to port 1
SETB P1.0 ;RS=1 for DATA
CLR P1.1 ;R/W=0 for write
SETB P1.2 ;E=1 for high pulse
CLR P1.2 ;E=0 for H-to-L pulse
ACALL DELAY ;give LCD some time
RET
DATA WORD SUBROUTINE

16. DELAY: MOV R3,#255 ;OUTER COUNT
HERE2: MOV R4,#255 ;INNER COUNT
HERE: DJNZ R4,HERE ;stay until R4 becomes 0
DJNZ R3,HERE2
RET
END
DELAY SUBROUTINE

17. Output with KEIL program and Proteus Simulation

18. Thank you !!!
Dr. Vikas Dongre
HOD Electronics
Government Polytechnic Washim
dongrevj1@gmail.com