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LCD Library

 

LCD Library 

The mikroC PRO for PIC 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 creating a set of custom Lcd characters use Lcd Custom Character Tool.   

 

 

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 RB4_bit;
extern sfr sbit LCD_EN: Enable line. sbit LCD_EN at RB5_bit;
extern sfr sbit LCD_D7; Data 7 line. sbit LCD_D7 at RB3_bit;
extern sfr sbit LCD_D6; Data 6 line. sbit LCD_D6 at RB2_bit;
extern sfr sbit LCD_D5; Data 5 line. sbit LCD_D5 at RB1_bit;
extern sfr sbit LCD_D4; Data 4 line. sbit LCD_D4 at RB0_bit;
extern sfr sbit LCD_RS_Direction; Register Select direction pin. sbit LCD_RS_Direction at TRISB4_bit;
extern sfr sbit LCD_EN_Direction; Enable direction pin. sbit LCD_EN_Direction at TRISB5_bit;
extern sfr sbit LCD_D7_Direction; Data 7 direction pin. sbit LCD_D7_Direction at TRISB3_bit;
extern sfr sbit LCD_D6_Direction; Data 6 direction pin. sbit LCD_D6_Direction at TRISB2_bit;
extern sfr sbit LCD_D5_Direction; Data 5 direction pin. sbit LCD_D5_Direction at TRISB1_bit;
extern sfr sbit LCD_D4_Direction; Data 4 direction pin. sbit LCD_D4_Direction at TRISB0_bit;

Library Routines

 

 

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 RB4_bit;
sbit LCD_EN at RB5_bit;
sbit LCD_D7 at RB3_bit;
sbit LCD_D6 at RB2_bit;
sbit LCD_D5 at RB1_bit;
sbit LCD_D4 at RB0_bit;

// Pin direction
sbit LCD_RS_Direction at TRISB4_bit;
sbit LCD_EN_Direction at TRISB5_bit;
sbit LCD_D7_Direction at TRISB3_bit;
sbit LCD_D6_Direction at TRISB2_bit;
sbit LCD_D5_Direction at TRISB1_bit;
sbit LCD_D4_Direction at TRISB0_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:

// LCD module connections
sbit LCD_RS at RB4_bit;
sbit LCD_EN at RB5_bit;
sbit LCD_D4 at RB0_bit;
sbit LCD_D5 at RB1_bit;
sbit LCD_D6 at RB2_bit;
sbit LCD_D7 at RB3_bit;

sbit LCD_RS_Direction at TRISB4_bit;
sbit LCD_EN_Direction at TRISB5_bit;
sbit LCD_D4_Direction at TRISB0_bit;
sbit LCD_D5_Direction at TRISB1_bit;
sbit LCD_D6_Direction at TRISB2_bit;
sbit LCD_D7_Direction at TRISB3_bit;
// End LCD module connections

char txt1[] = "mikroElektronika";    
char txt2[] = "EasyPIC6";
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(){
  ANSEL  = 0;                        // Configure AN pins as digital I/O
  ANSELH = 0;
  C1ON_bit = 0;                      // Disable comparators
  C2ON_bit = 0;

  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(2,5,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<8; i++) {             // Move text to the left 7 times
      Lcd_Cmd(_LCD_SHIFT_LEFT);
      Move_Delay();
    }

    for(i=0; i<8; i++) {             // Move text to the right 7 times
      Lcd_Cmd(_LCD_SHIFT_RIGHT);
      Move_Delay();
    }
  }
}

 

Circuit Diagram

Lcd Library example circuit

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