The mikroC PRO for AVR provides a library for communication with Lcds (with HD44780 compliant controllers) through the 4-bit interface. An example of Lcd connections is given on the schematic at the bottom of this page.
For LCD Basics: Character LCD Basics
Lcd Library
External dependencies of Lcd Library
The following variables must be defined in all projects using Lcd Library :
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Description :
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Example :
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extern sfr sbit LCD_RS:
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Register Select line.
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sbit LCD_RS at PORTD2_bit;
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extern sfr sbit LCD_EN:
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Enable line.
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sbit LCD_EN at PORTD3_bit;
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extern sfr sbit LCD_D7;
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Data 7 line.
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sbit LCD_D7 at PORTD4_bit;
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extern sfr sbit LCD_D6;
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Data 6 line.
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sbit LCD_D6 at PORTD5_bit;
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extern sfr sbit LCD_D5;
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Data 5 line.
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sbit LCD_D5 at PORTD6_bit;
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extern sfr sbit LCD_D4;
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Data 4 line.
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sbit LCD_D4 at PORTD7_bit;
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extern sfr sbit LCD_RS_Direction;
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Register Select direction pin.
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sbit LCD_RS_Direction at DDD2_bit;
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extern sfr sbit LCD_EN_Direction;
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Enable direction pin.
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sbit LCD_EN_Direction at DDD3_bit;
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extern sfr sbit LCD_D7_Direction;
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Data 7 direction pin.
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sbit LCD_D7_Direction at DDD4_bit;
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extern sfr sbit LCD_D6_Direction;
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Data 6 direction pin.
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sbit LCD_D6_Direction at DDD5_bit;
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extern sfr sbit LCD_D5_Direction;
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Data 5 direction pin.
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sbit LCD_D5_Direction at DDD6_bit;
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extern sfr sbit LCD_D4_Direction;
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Data 4 direction pin.
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sbit LCD_D4_Direction at DDD7_bit;
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Library Routines
Lcd_Init
Prototype
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void Lcd_Init();
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Returns
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Nothing.
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Description
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Initializes Lcd module.
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Requires
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Global variables:
must be defined before using this function.
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Example
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// Lcd pinout settings
sbit LCD_RS at PORTD2_bit;
sbit LCD_EN at PORTD3_bit;
sbit LCD_D7 at PORTD4_bit;
sbit LCD_D6 at PORTD5_bit;
sbit LCD_D5 at PORTD6_bit;
sbit LCD_D4 at PORTD7_bit;
// Pin direction
sbit LCD_RS_Direction at DDD2_bit;
sbit LCD_EN_Direction at DDD3_bit;
sbit LCD_D7_Direction at DDD4_bit;
sbit LCD_D6_Direction at DDD5_bit;
sbit LCD_D5_Direction at DDD6_bit;
sbit LCD_D4_Direction at DDD7_bit;
...
Lcd_Init();
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Lcd_Out
Prototype
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void Lcd_Out(char row, char column, char *text);
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Returns
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Nothing.
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Description
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Prints text on Lcd starting from specified position. Both string variables and literals can be passed as a text.
Parameters :
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Requires
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Example
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// Write text "Hello!" on Lcd starting from row 1, column 3:
Lcd_Out(1, 3, "Hello!");
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Lcd_Out_Cp
Prototype
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void Lcd_Out_Cp(char *text);
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Returns
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Nothing.
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Description
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Prints text on Lcd at current cursor position. Both string variables and literals can be passed as a text.
Parameters :
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Requires
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Example
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// Write text "Here!" at current cursor position:
Lcd_Out_Cp("Here!");
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Lcd_Chr
Prototype
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void Lcd_Chr(char row, char column, char out_char);
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Returns
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Nothing.
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Description
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Prints character on Lcd at specified position. Both variables and literals can be passed as a character.
Parameters :
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Requires
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Example
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// Write character "i" at row 2, column 3:
Lcd_Chr(2, 3, 'i');
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Lcd_Chr_Cp
Prototype
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void Lcd_Chr_Cp(char out_char);
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Returns
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Nothing.
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Description
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Prints character on Lcd at current cursor position. Both variables and literals can be passed as a character.
Parameters :
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Requires
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Example
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// Write character "e" at current cursor position:
Lcd_Chr_Cp('e');
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Lcd_Cmd
Prototype
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void Lcd_Cmd(char out_char);
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Returns
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Nothing.
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Description
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Sends command to Lcd.
Parameters :
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Requires
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Example
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// Clear Lcd display:
Lcd_Cmd(_LCD_CLEAR);
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Available Lcd Commands
Lcd Command
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Purpose
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_LCD_FIRST_ROW
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Move cursor to the 1st row
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_LCD_SECOND_ROW
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Move cursor to the 2nd row
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_LCD_THIRD_ROW
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Move cursor to the 3rd row
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_LCD_FOURTH_ROW
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Move cursor to the 4th row
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_LCD_CLEAR
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Clear display
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_LCD_RETURN_HOME
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Return cursor to home position, returns a shifted display to its original position. Display data RAM is unaffected.
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_LCD_CURSOR_OFF
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Turn off cursor
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_LCD_UNDERLINE_ON
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Underline cursor on
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_LCD_BLINK_CURSOR_ON
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Blink cursor on
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_LCD_MOVE_CURSOR_LEFT
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Move cursor left without changing display data RAM
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_LCD_MOVE_CURSOR_RIGHT
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Move cursor right without changing display data RAM
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_LCD_TURN_ON
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Turn Lcd display on
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_LCD_TURN_OFF
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Turn Lcd display off
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_LCD_SHIFT_LEFT
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Shift display left without changing display data RAM
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_LCD_SHIFT_RIGHT
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Shift display right without changing display data RAM
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Example
The following code demonstrates usage of the Lcd Library routines:
// LCD module connections
sbit LCD_RS at PORTD2_bit;
sbit LCD_EN at PORTD3_bit;
sbit LCD_D4 at PORTD4_bit;
sbit LCD_D5 at PORTD5_bit;
sbit LCD_D6 at PORTD6_bit;
sbit LCD_D7 at PORTD7_bit;
sbit LCD_RS_Direction at DDD2_bit;
sbit LCD_EN_Direction at DDD3_bit;
sbit LCD_D4_Direction at DDD4_bit;
sbit LCD_D5_Direction at DDD5_bit;
sbit LCD_D6_Direction at DDD6_bit;
sbit LCD_D7_Direction at DDD7_bit;
// End LCD module connections
char txt1[] = "Embedded";
char txt2[] = "Projects";
char txt3[] = "Lcd 4 bit";
char txt4[] = "Tutorial";
char i; // Loop variable
void Move_Delay() { // Function used for text moving
Delay_ms(500); // You can change the moving speed here
}
void main(){
Lcd_Init(); // Initialize LCD
Lcd_Cmd(_LCD_CLEAR); // Clear display
Lcd_Cmd(_LCD_CURSOR_OFF); // Cursor off
Lcd_Out(1,6,txt3); // Write text in first row
Lcd_Out(2,6,txt4); // Write text in second row
Delay_ms(2000);
Lcd_Cmd(_LCD_CLEAR); // Clear display
Lcd_Out(1,1,txt1); // Write text in first row
Lcd_Out(2,4,txt2); // Write text in second row
Delay_ms(2000);
// Moving text
for(i=0; i<4; i++) { // Move text to the right 4 times
Lcd_Cmd(_LCD_SHIFT_RIGHT);
Move_Delay();
}
while(1) { // Endless loop
for(i=0; i<7; i++) { // Move text to the left 7 times
Lcd_Cmd(_LCD_SHIFT_LEFT);
Move_Delay();
}
for(i=0; i<7; i++) { // Move text to the right 7 times
Lcd_Cmd(_LCD_SHIFT_RIGHT);
Move_Delay();
}
}
}
Circuit diagram
