INTERFACING LCD WITH 8051 MIROCONTROLLER with code

Page Contents

• 1 16×2 LCD:
• 2 LCD PIN DISCRIPTION
• 3 LCD interfacing WORKING
• 4 LCD INTERFACING WITH 8051 MICROCONTROLLER
• 5 TO INITIALIZE LCD for interfacing with 8051 microcontroller
• 6 Video simulation of lcd interfacing with 8051 microcontroller
• 7 CODE of lcd interfacing with 8051 microcontroller

16×2 LCD:

We can use any type of LCD like 16×2, 8×1, 16×4, 8×2, 16×1, 20×1, 20×2 etc. Here we will use 16×2 Liquid Crystal Display. It can display 32 characters at a time in two rows. LM016L is a 16×2 LCD module.There are 16 pins in this LCD module, the pin configuration us given below:

LCD PIN DIAGRAM:

LCD PIN DISCRIPTION

Pin 1                GND   (0v)

Pin 2                Vcc      (5v)

Pin 3                VEE    (contrast adjustment through variable resistor)

Pin 4                RS       (command register when low, data register when high)

Pin 5                R/W     (high for read from register, low for write to the register)

Pin 6                EN       (sends data to data pins when high to low pulse is given)

Pin 7-14           DB0-DB7 (8-bit data pins)

Pin 15              LED+  (backlight, Vcc 5v)

Pin 16              LED-   (backlight, GND 0v)

LCD interfacing WORKING

EN pin is for enabling the module. A high to low transition at this pin will enable the LCD module. ThisLM016L has two built in registers namely:

• Data register
• Command register

Data register: It is for placing the data which is to be displayed. Data can be any character, alphabet or number.High logic at the RS pin will select the data register. By making RS pin high and putting data in the 8 bit data line (DB0 to DB7), the LCD module will recognize it as a data to be displayed.

Command register:It is for placing the commands. There is a set of commands for LCD to perform specific tasks. Low logic at the RS pin will select the command register.By making RS pin low and putting data on the data line, the LCD module will recognize it as a command.Some of the instructions/commands are given below:

Code (in Hex)                         Working of LCD commands

0x01                                        Clear displays

0x02                                        return home

0x06                                        for entry mode

0x80                                        Force cursor to beginning of 1^st line

0xC0                                       Force cursor to beginning of 2^nd line

0x90                                        Force cursor to beginning of 3^rd line

0xD0                                       Force cursor to beginning of 4^th line

0x08                                        Display off, cursor off

0x0E                                        Display on, cursor on

0x0C                                       Display on, cursor off

0x0F                                        Display on, cursor blinking

0x10                                        Shift cursor position to left

0x14                                        Shift cursor position to right

0x38                                        2 lines and 5×7 matrix (8-bit mode)

0x28                                        2 lines and 5×7 matrix (4-bit mode)

R/W pin is for selecting between read and write modes. High level at this pin enables read mode and low level at this pin enables write mode.

DB0 to DB7 are the data pins. The data to be displayed and the commands are placed on these pins.

For glowing backlight LED, LED+ (anode of back light LED)is connected to Vcc through a suitable series current limiting resistor (for contrast adjustment). LED-(cathode of the back light LED) is connected to ground.

LCD INTERFACING WITH 8051 MICROCONTROLLER

This LCD can be operated in 4-bit mode (using only 4 data lines) or 8-bit mode (using all 8 data lines). Here we will useit in 8-bit mode. First of all LCD is initialized and then it can be used for sending data and commands. Reset and Enable of LCD is connected to port 1 of 8051 microcontroller. Data lines of LCD are connected to port 2 of 8051 microcontroller. R/W is connected to ground since we have to just write data and command (not read operation). This gives a little ease so that we don’t need to make this pin low in the code.

TO INITIALIZE LCD for interfacing with 8051 microcontroller

To initialize LCD with 8051 microcontroller, following instruction are to be executed:

0x38    (is used for 8-bit data initialization)

0x0C   (display on, cursor off)

0x01    (for clearing screen)

0x80    (force cursor to beginning of 1^st line)

TO SENDDATA:

For displaying any character whether it is number, alphabet or character, following steps should be follow:

• For display data, register select (RS pin) should be high, RS = 1.
• Place data byte on the data register.
• Pulse the Enable pin (EN pin) from high to low.
• Configure the R/W to write mode. For write mode,R/W = 0.
• Repeat above steps for sending another data.

TO SEND COMMAND:

To instruct LCD for performing specific task for example displaying character in second row instead of one, following steps should be taken:

• For command mode, register select (RS pin) should be low, RS = 0.
• Place data byte on the command register.
• Pulse the Enable pin (EN pin) from high to low.
• Read/Write should be low (write mode), R/W = 0.
• Repeat above steps for sending another command.

PROTEUS SIMULATION of lcd interfacing with 8051 microcontroller:

Video simulation of lcd interfacing with 8051 microcontroller

CODE of lcd interfacing with 8051 microcontroller

#include<reg51.h>

voidlcd_init(void);

voidwritecmd(int);

voidwritedata(char);

void delay(int);

sbit RS = P1^0;

sbit E  = P1^1;

sbit led = P1^2;

inti=0;

void main()

{

P0 = 0x00;   //not used

P1 = 0x00;   //output port for setting RS and EN

P2 = 0x00;   //used as data output port

P3 = 0x00;   //not used
led = 1;
lcd_init();

writedata(‘W’);

delay(5000000);

writedata(‘e’);

delay(5000000);

writedata(‘l’);

delay(5000000);

writedata(‘c’);

delay(5000000);

writedata(‘o’);

delay(5000000);

writedata(‘m’);

delay(5000000);

writedata(‘e’);

delay(5000000);

writedata(‘ ‘);

delay(5000000);

writedata(‘T’);

delay(5000000);

writedata(‘o’);

delay(5000000);
writecmd(0x01);                      //clear display
writedata(‘w’);

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INTERFACING LCD WITH 8051 MIROCONTROLLER with code