1. UNIVERSAL COLLEGE OF ENGINEERING & TECHNOLOGY

2. Microcontroller & Interfacing
E.C Engg. Parmar Ramendra ( ) Guided by :- Prof. Parth Patel (E.C Department)

3. LCD (Liquid Crystal Display ) Interfacing with ATmega32

4. What is LCD ?
LCD stands for Liquid Crystal Display, it is an electronic device which is used for data display. LCDs are preferable over seven segments and LEDs as they can easily represent data in form of alphabets, characters, numbers or animations. LCDs are very easy to program and make your work quite attractive and simple. Numerous types of LCDs are available in market such as 16X2, 16X4, 20X2, 20X4, graphical LCDs (128X64) etc.
The LCD which we are using is 16X2 alphanumeric LCD, it display 32 characters in two rows means in one row we have 16 characters.

5. Pin Description of LCD Pins Symbol Functions 1 Vss Supply pin (+5V DC)2
Vdd
Ground pin 3
VEE
Contrast pin 4 RS
Register selection pin (Either Data or Command)
RS=0 Command register
RS=1 Data register 5 RW
Selects Read or Write operation
RW=0 Write operation
RW=1 Read operation 6 E
Enable pin

6. Pin Description of LCD Pins Symbol Functions 7 DB0 Data bus bit 0 89
DB2
Data bus bit 2 10
DB3
Data bus bit 3 11
DB4
Data bus bit 4 12
DB5
Data bus bit 5 13
DB6
Data bus bit 6 14
DB7
Data bus bit 7 (Also used as Busy pin)

7. How to Program LCD ?
Basically there are two registers, command and data. When we are giving command to LCD, we select command register and when we are sending data to LCD for display, we select data register. Command is an instruction given to LCD in order to perform required function according to the given command. In order to display textual information, data is send to LCD.

8. Sending Commands & Data on LCD
For sending commands on LCD we have to write command on data pins. For this, selects:
RS = 0 selects command register
RW = 1 selects write operation
E = make enable pin from high to low
Sending Data :-
For sending data on LCD we have to write data on data pins. For this, selects:
RS = 1 selects data register
RW = 0 selects write operation

9. LCD Interfacing circuit with ATmega32

10. Code for interfacing LCD
We use Atmel studio 6 for development of code and the code is written in C language.
#include<avr/io.h>
#include<util/delay.h>
#define LCD_data PORTA
#define ctrl PORTB
#define en PB2
#define rw PB1
#define rs PB0

11. Continue….
void LCD_cmd(unsigned char cmd); void init_LCD (void); void LCD_write(unsigned char data); void LCD_write_string(); unsigned int press; int main (void) { DDRA=0XFF; DDRB=0X07; init_LCD(); LCD_write_string("Ramendra Parmar");

12. Continue….
LCD_cmd(0xc0); return 0; } void init_LCD(void) { LCD_cmd(0x38); _delay_ms(1);

13. Continue….
_delay_ms(1); LCD_cmd(0x38); LCD_cmd(0x06); LCD_cmd(0x0c); LCD_cmd(0x01);

14. Continue….
LCD_cmd(0x02); _delay_ms(1); return ; } void LCD_cmd(unsigned char cmd) { PORTA=cmd; ctrl=(0<<rs)|(0<<rw)|(1<<en); ctrl=(0<<rs)|(0<<rw)|(0<<en); _delay_ms(150);

15. Continue….
return; } void LCD_write(unsigned char data) { PORTA=data; ctrl=(1<<rs)|(0<<rw)|(1<<en); _delay_ms(1); ctrl=(1<<rs)|(0<<rw)|(0<<en); _delay_ms(150);

16. Continue….
void LCD_write_string(unsigned char *str) { int i=0; while(str[i]!='\0') LCD_write(str[i]); i++; } return;

17. Basic commands used in LCD display
Hex Command
Functions
0x01
Clear screen
0x02
return home
0x04
Cursor decrement
0x05
Display shifts to right
0x06
Cursor increment
0x07
Display shifts to left
0x08
Cursor and display OFF
0x10
Cursor position Shifts to left
0x14
Cursor position shifts to right

18. Basic commands used in LCD display
Hex Command
Functions
0x80
Move cursor to the beginning of first line
0x0C
Display ON, cursor OFF
0XC0
Move cursor to the beginning of second line
0x0A
Display OFF, cursor ON
0x0E
Display ON, cursor blinking
0x30
For display in one line in 8-bit mode
0x20
For display in one line in 4-bit mode
0x18
Shift complete data to left side
0x1C
Shift complete data to right side

19. Thank You….