Discussing using LCD for interacting with system user

1. 1
04-Interfacing LCD
Displays.
By : Mohamed Fawzy
Programming AVR Microcontrollers
© Mohamed F.A.B 2015

2. Lecture Notes:
2
o Set Your Phone To Vibration Mode.
o Ask any time.
o During labs, Feel Free To Check Any Materials or
Internet.
o Slides are self content.
o Feel Free To Share This Materials With Your Friends.
o Work Hard For Achieving Most Of This Course.
© Mohamed F.A.B 2015

3. 3
Don't Forget !!!!
© Mohamed F.A.B 2015
Any Expert Was Once A Beginner


4. 4
Lesson(10).
© Mohamed F.A.B 2015
Lesson (10):
Interfacing LCDs displays with Microcontroller.

5. 5
Lesson (10) Topics.
© Mohamed F.A.B 2015
► Intro to LCDs screens.
► LCD Hardware Connections.
► LCD built in Functions in MIKROC.
► Displaying Numbers On LCD.
► How to Display Custom Symbols or Characters on LCD.
► How to Connect Multiple LCD With MC using Same Pins.
► Let's Have Fun With LCD.

6. 6
Intro To LCDs Screens.
© Mohamed F.A.B 2015
 LCD stands for Liquid Crystal Display.
 It can be used to display anything (virtually
anything!).
 There are two common types of LCDs:
 Character LCD : Used For
Displaying Only
Characters, Numbers and
some Custom Symbols.
 Graphical LCD : Used For
Displaying almost
everything (Text, symbols
and images).
“Will be discussed on Level 2”

7. 7
LCDs Memory.
© Mohamed F.A.B 2015
 Memory in LCD divided into Three types:
 DDRAM Memory: storing characters to be
displayed.
 CGROM Memory: contains standard
character map with all characters that
can be displayed on the screen.
 CGRAM Memory: a part from standard
characters, the LCD display can also
display symbols defined by the user itself.
We can use CGRAM to display custom symbols on LCD.
NOTE:

8. 8
LCD Hardware Connections.
© Mohamed F.A.B 2015
• Pins[RS,R/W,EN] Control Lines.
• Pins[D0:D7] Data Lines.
Don't swap power pins to
avoid damaging your LCD.
Take Care:

9. 9
alcd.h functions.
© Mohamed F.A.B 2015
 Initializing the LCD controller
void lcd_init(unsigned char lcd_columns);
EX:
Lcd_init(16); //for 2*16 LCD
 Writing character to LCD
void lcd_putchar(char c);
EX:
Lcd_write (‘A’); //display A on LCD
 Defining position of cursor (x,y)
void lcd_gotoxy(unsigned char x, unsigned char y);
EX:
lcd_gotoxy(0,0); //start from column 0 and row 0
 write the string str located in SRAM to the LCD
void lcd_puts(char *str);
EX:
lcd_puts(“Hello LCD !!!”);

10. 10
alcd.h functions. Cont’
© Mohamed F.A.B 2015
 Clearing the LCD
void lcd_clear(void);
EX:
lcd_clear(); //delete any data on LCD
 Write byte to the LCD character generator or LCD CGRAM
void write_byte(unsigned char address, unsigned char data);
EX:
void write_byte(char0, 0);
 Writing command to LCD
void _lcd_write_data(unsigned char cmd);
EX:
void _lcd_write_data(0x0E); //display LCD cursor

11. 11
LCD useful commands codes.
© Mohamed F.A.B 2015
Code Function
0x0C Cursor OFF
0x0E Cursor underline
0x0F Cursor ON
0x10 Move cursor left by one character.
0x14 Move cursor right by one character.
#define _LCD_CURSOR_OFF 0x0C
#define _LCD_CURSOR_UNDERLINE 0x0E
#define _LCD_CURSOR_ON 0x0F
#define _LCD_CURSOR_LEFT 0x10
#define _LCD_CURSOR_RIGHT 0x14
TIP

12. 12
Displaying Numbers On LCD.
© Mohamed F.A.B 2015
• LCD displays data into ASCII format. ASCII Symbol
Do (00:99) UP Down Counter With Two Buttons.
Exercise:

13. 13
Displaying Custom Symbols On LCD.
© Mohamed F.A.B 2015
 In some cases you may need to
display characters and symbols that
not defined in CGROM.
 You need to define your symbol into
CGRAM.
1
2
3
 We use “LCD Custom Char Builder” to draw our pattern.
http://extremeelectronics.co.in/avrtutorials/download/LCDCustomCharBuilder.zip

14. 14
Displaying Custom Symbols On LCD. Cont’
© Mohamed F.A.B 2015
Exercise:
#include <io.h>
#include <alcd.h>
#include <delay.h>
// Declare your global variables here
flash unsigned char char0[8]={0x0A, 0x1F, 0x1F, 0x1F, 0x1F, 0x0E, 0x04, 0
void define_char(unsigned char flash *pc, unsigned char char_code){
unsigned char i,a;
a=(char_code<<3)|0x040;
for (i=0;i<8;i++)lcd_write_byte(a++,*pc++);
}
void main(void)
{
lcd_init(16);
lcd_gotoxy(0,0);
while (1)
{
define_char(char0,0);
lcd_puts("I ");
lcd_putchar(0);
lcd_puts(" AVR");
}

15. 15
Connecting Multiple LCD with same I/O Pins.
© Mohamed F.A.B 2015
 What if we need to use multiple LCD in one project ??!!!!.
 We can do that using latch IC 74HC573.
 Simply, this IC pass data from input pins to output pins in
case we enables that action.
We need to interface 2 LCDs with MC using
PORTC, then displaying “LCD_1”on first LCD
and displaying “LCD_2” on second LCD.
Exercise:
LCD_1 LCD_2

16. 16
Let's have Fun With LCD .
© Mohamed F.A.B 2015

17. 17
Questions:
© Mohamed F.A.B 2015

18. Thank You All 
18
mo7amed.fawzy33@gmail.com
01006032792
fawzy.fab@gmail.com
© Mohamed F.A.B 2015