Transcript
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04-Interfacing LCD Displays.
By : Mohamed Fawzy
Programming AVR Microcontrollers
© Mohamed F.A.B 2015
Lecture Notes:
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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
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Don't Forget !!!!
© Mohamed F.A.B 2015
Any Expert Was Once A Beginner
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Lesson(10).
© Mohamed F.A.B 2015
Lesson (10):
Interfacing LCDs displays with Microcontroller.
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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.
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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”
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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:
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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:
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alcd.h functions.
© Mohamed F.A.B 2015
Initializing the LCD controllervoid lcd_init(unsigned char lcd_columns);
EX:
Lcd_init(16); //for 2*16 LCD
Writing character to LCDvoid 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 LCDvoid lcd_puts(char *str);
EX:
lcd_puts(“Hello LCD !!!”);
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alcd.h functions. Cont’
© Mohamed F.A.B 2015
Clearing the LCDvoid lcd_clear(void);
EX:
lcd_clear(); //delete any data on LCD
Write byte to the LCD character generator or LCD CGRAMvoid write_byte(unsigned char address, unsigned char data);
EX:
void write_byte(char0, 0);
Writing command to LCDvoid _lcd_write_data(unsigned char cmd);
EX:
void _lcd_write_data(0x0E); //display LCD cursor
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LCD useful commands codes.
© Mohamed F.A.B 2015
Code Function0x0C 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
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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:
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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.
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We use “LCD Custom Char Builder” to draw our pattern.http://extremeelectronics.co.in/avrtutorials/download/LCDCustomCharBuilder.zip
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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, 0x00};
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");
}
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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
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Let's have Fun With LCD .
© Mohamed F.A.B 2015
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Questions:
© Mohamed F.A.B 2015
Thank You All
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mo7amed.fawzy33@gmail.com
01006032792
fawzy.fab@gmail.com
© Mohamed F.A.B 2015
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