2. In This Project
• We have made LCD interfacing using
8051 microcontroller .
• We have used :-
• 8051 as CPU.
• LCD Display of 2*16 characters for
displaying “ ENTER PASSWORD “
3. • Basically the circuit has :-
• 1. 8051 IC
• 2. DISPLAY UNIT
• 3. POWER SUPPLY
4. List of Components Used
Sr. no Equipment Quantity
1 IC- AT89C51 μC 1
2 5V-POWER
SUPPLY(ADAPTER)
+DC CONNECTOR
1
3 BREAD BOARD 1 or 2
4 SOLDERING IRON 1
5 CRYSTAL(11.059MHz
)
1
6 CAPACITORS(33pf) 2
7 PUSH BUTTON
SWITCH
1
8 8.2 KΩ RESISTOR 1
9 560 Ω RESISTOR 1
10 LED 1 or 2
11 16×2 LCD DISPLAY 1
12 10K
POTENTIOMETER(to
1
6. LCD Interfacing
• Liquid Crystal Displays (LCDs)
• cheap and easy way to display text
• Various configurations (1 line × 20 characters, 2 lines
×16 characters ).
• The display has two register
– command register
– data register
• By RS you can select register
• Data lines (DB7-DB0) used to transfer data and
commands
7. Alphanumeric LCD Interfacing
• Pinout
– 8 data pins D7:D0
– RS: Data or Command
Register Select
– R/W: Read or Write
– E: Enable (Latch data)
• RS – Register Select
– RS = 0 → Command Register
– RS = 1 → Data Register
• R/W = 0 → Write , R/W = 1 → Read
• E – Enable
– Used to latch the data present on the data pins.
• D0 – D7
– Bi-directional data/command pins.
– Alphanumeric characters are sent in ASCII format.
E
R/W
RS
DB7–DB0
LCD
controller
communications
bus
Microcontroller
8
LCD Module
8. LCD Commands
• The LCD’s internal controller can accept several
commands and modify the display accordingly.
These commands would be things like:
– Clear screen
– Return home
– Decrement/Increment cursor
• After writing to the LCD, it takes some time for it to
complete its internal operations. During this time, it
will not accept any new commands or data.
– We need to insert time delay between any two commands or
data sent to LCD
9. Pin No: Name Function
1 VSS This pin must be connected to the ground
2 VCC Power supply (+5V )
3 VEE Power supply source to control contrast
4 RS Register select,
RS=0 to select command register
RS=1 to select data register
5 R/W Read or write
R/W =0 for write
R/W=1 for read
6 E Enable
7 DB0 8 bit Data bus
8 DB1 8 bit Data bus
9 DB2 8 bit Data bus
10 DB3 8 bit Data bus
11 DB4 8 bit Data bus
12 DB5 8 bit Data bus
13 DB6 8 bit Data bus
14 DB7 8 bit Data bus
15 LED+ Back light LED+
16 LED- Back light LED-
13. Working Of Project
• The 220V AC supply is converted into 5
Volts by using the adapter power supply
section.
• After supplying power to the circuit, it
works according to the programming done
in 8051.
14. Algorithm of LCD Programming
using 8051
Algorithm to send data to LCD:
1. Make R/W low
2. Make RS=0; if data byte is command
RS=1; if data byte is data (ASCII value)
3. Place data byte on data register
4. Pulse E (HIGH to LOW)
5. Repeat the steps to send another data byte
