Lcd Library

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.

Library Dependency Tree

External dependencies of Lcd Library

The following variables must be defined in all projects using Lcd Library :	Description :	Example :
`extern sfr sbit LCD_RS:`	Register Select line.	`sbit LCD_RS at PORTD2_bit;`
`extern sfr sbit LCD_EN:`	Enable line.	`sbit LCD_EN at PORTD3_bit;`
`extern sfr sbit LCD_D7;`	Data 7 line.	`sbit LCD_D7 at PORTD4_bit;`
`extern sfr sbit LCD_D6;`	Data 6 line.	`sbit LCD_D6 at PORTD5_bit;`
`extern sfr sbit LCD_D5;`	Data 5 line.	`sbit LCD_D5 at PORTD6_bit;`
`extern sfr sbit LCD_D4;`	Data 4 line.	`sbit LCD_D4 at PORTD7_bit;`
`extern sfr sbit LCD_RS_Direction;`	Register Select direction pin.	`sbit LCD_RS_Direction at DDD2_bit;`
`extern sfr sbit LCD_EN_Direction;`	Enable direction pin.	`sbit LCD_EN_Direction at DDD3_bit;`
`extern sfr sbit LCD_D7_Direction;`	Data 7 direction pin.	`sbit LCD_D7_Direction at DDD4_bit;`
`extern sfr sbit LCD_D6_Direction;`	Data 6 direction pin.	`sbit LCD_D6_Direction at DDD5_bit;`
`extern sfr sbit LCD_D5_Direction;`	Data 5 direction pin.	`sbit LCD_D5_Direction at DDD6_bit;`
`extern sfr sbit LCD_D4_Direction;`	Data 4 direction pin.	`sbit LCD_D4_Direction at DDD7_bit;`

Lcd_Init

Prototype	void Lcd_Init();
Returns	Nothing.
Description	Initializes Lcd module.
Requires	Global variables: `LCD_D7:` Data bit 7 `LCD_D6:` Data bit 6 `LCD_D5:` Data bit 5 `LCD_D4:` Data bit 4 `LCD_RS:` Register Select (data/instruction) signal pin `LCD_EN:` Enable signal pin `LCD_D7_Direction:` Direction of the Data 7 pin `LCD_D6_Direction:` Direction of the Data 6 pin `LCD_D5_Direction:` Direction of the Data 5 pin `LCD_D4_Direction:` Direction of the Data 4 pin `LCD_RS_Direction:` Direction of the Register Select pin `LCD_EN_Direction:` Direction of the Enable signal pin must be defined before using this function.
Example	// 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();

Lcd_Out

Prototype	void Lcd_Out(char row, char column, char *text);
Returns	Nothing.
Description	Prints text on Lcd starting from specified position. Both string variables and literals can be passed as a text. Parameters : `row:` starting position row number `column:` starting position column number `text:` text to be written
Requires	The Lcd module needs to be initialized. See Lcd_Init routine.
Example	// Write text "Hello!" on Lcd starting from row 1, column 3: Lcd_Out(1, 3, "Hello!");

Lcd_Out_Cp

Prototype	void Lcd_Out_Cp(char *text);
Returns	Nothing.
Description	Prints text on Lcd at current cursor position. Both string variables and literals can be passed as a text. Parameters : `text:` text to be written
Requires	The Lcd module needs to be initialized. See Lcd_Init routine.
Example	// Write text "Here!" at current cursor position: Lcd_Out_Cp("Here!");

Lcd_Chr

Prototype	void Lcd_Chr(char row, char column, char out_char);
Returns	Nothing.
Description	Prints character on Lcd at specified position. Both variables and literals can be passed as a character. Parameters : `row:` writing position row number `column:` writing position column number `out_char:` character to be written
Requires	The Lcd module needs to be initialized. See Lcd_Init routine.
Example	// Write character "i" at row 2, column 3: Lcd_Chr(2, 3, 'i');

Lcd_Chr_Cp

Prototype	void Lcd_Chr_Cp(char out_char);
Returns	Nothing.
Description	Prints character on Lcd at current cursor position. Both variables and literals can be passed as a character. Parameters : `out_char:` character to be written
Requires	The Lcd module needs to be initialized. See Lcd_Init routine.
Example	// Write character "e" at current cursor position: Lcd_Chr_Cp('e');

Lcd_Cmd

Prototype	void Lcd_Cmd(char out_char);
Returns	Nothing.
Description	Sends command to Lcd. Parameters : `out_char:` command to be sent Note : Predefined constants can be passed to the function, see Available Lcd Commands.
Requires	The Lcd module needs to be initialized. See Lcd_Init table.
Example	// Clear Lcd display: Lcd_Cmd(_LCD_CLEAR);

Available Lcd Commands

Lcd Command	Purpose
_LCD_FIRST_ROW	Move cursor to the 1st row
_LCD_SECOND_ROW	Move cursor to the 2nd row
_LCD_THIRD_ROW	Move cursor to the 3rd row
_LCD_FOURTH_ROW	Move cursor to the 4th row
_LCD_CLEAR	Clear display
_LCD_RETURN_HOME	Return cursor to home position, returns a shifted display to its original position. Display data RAM is unaffected.
_LCD_CURSOR_OFF	Turn off cursor
_LCD_UNDERLINE_ON	Underline cursor on
_LCD_BLINK_CURSOR_ON	Blink cursor on
_LCD_MOVE_CURSOR_LEFT	Move cursor left without changing display data RAM
_LCD_MOVE_CURSOR_RIGHT	Move cursor right without changing display data RAM
_LCD_TURN_ON	Turn Lcd display on
_LCD_TURN_OFF	Turn Lcd display off
_LCD_SHIFT_LEFT	Shift display left without changing display data RAM
_LCD_SHIFT_RIGHT	Shift display right without changing display data RAM

Library Example

The following code demonstrates usage of the Lcd Library routines:

Copy Code To Clipboard

// 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[] = "mikroElektronika";    
char txt2[] = "EasyAVR6";
char txt3[] = "Lcd4bit";
char txt4[] = "example";

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();
    }

  }
}

Lcd HW connection

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