Lcd Library

mikroPascal PRO for PIC32 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.

Library Dependency Tree

Lcd Library Dependency Tree

External dependencies of Lcd Library

The following variables must be defined in all projects using Lcd Library : Description : Example :
var LCD_RS : sbit; sfr; atomic; external; Register Select line. var LCD_RS : sbit at LATD0_bit;
var LCD_EN : sbit; sfr; atomic; external; Enable line. var LCD_EN : sbit at LATD1_bit;
var LCD_D7 : sbit; sfr; atomic; external; Data 7 line. var LCD_D7 : sbit at LATB3_bit;
var LCD_D6 : sbit; sfr; atomic; external; Data 6 line. var LCD_D6 : sbit at LATB2_bit;
var LCD_D5 : sbit; sfr; atomic; external; Data 5 line. var LCD_D5 : sbit at LATB1_bit;
var LCD_D4 : sbit; sfr; atomic; external; Data 4 line. var LCD_D4 : sbit at LATB0_bit;
var LCD_RS_Direction : sbit; sfr; atomic; external; Register Select direction pin. var LCD_RS_Direction : sbit at TRISD0_bit;
var LCD_EN_Direction : sbit; sfr; atomic; external; Enable direction pin. var LCD_EN_Direction : sbit at TRISD1_bit;
var LCD_D7_Direction : sbit; sfr; atomic; external; Data 7 direction pin. var LCD_D7_Direction : sbit at TRISB3_bit;
var LCD_D6_Direction : sbit; sfr; atomic; external; Data 6 direction pin. var LCD_D6_Direction : sbit at TRISB2_bit;
var LCD_D5_Direction : sbit; sfr; atomic; external; Data 5 direction pin. var LCD_D5_Direction : sbit at TRISB1_bit;
var LCD_D4_Direction : sbit; sfr; atomic; external; Data 4 direction pin. var LCD_D4_Direction : sbit at TRISB0_bit;

Library Routines

Lcd_Init

Prototype

procedure Lcd_Init();

Description

Initializes Lcd module.

Parameters

None.

Returns

Nothing.

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 module connections
var LCD_RS : sbit at LATD0_bit;
var LCD_EN : sbit at LATD1_bit;
var LCD_D4 : sbit at LATB0_bit;
var LCD_D5 : sbit at LATB1_bit;
var LCD_D6 : sbit at LATB2_bit;
var LCD_D7 : sbit at LATB3_bit;

var LCD_RS_Direction : sbit at TRISD0_bit;
var LCD_EN_Direction : sbit at TRISD1_bit;
var LCD_D4_Direction : sbit at TRISB0_bit;
var LCD_D5_Direction : sbit at TRISB1_bit;
var LCD_D6_Direction : sbit at TRISB2_bit;
var LCD_D7_Direction : sbit at TRISB3_bit;
// End LCD module connections

...
Lcd_Init();
Notes

None.

Lcd_Out

Prototype

procedure Lcd_Out(row, column: word; var text: string);

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
Returns

Nothing.

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!');
Notes

None.

Lcd_Out_Cp

Prototype

procedure Lcd_Out_Cp(var text: string);

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!');
Notes

None.

Lcd_Chr

Prototype

procedure Lcd_Chr(row, column: word, out_char: byte);

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
Returns

Nothing.

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');
Notes

None.

Lcd_Chr_Cp

Prototype

procedure Lcd_Chr_Cp(out_char: byte);

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
Returns

Nothing.

Requires

The Lcd module needs to be initialized. See Lcd_Init routine.

Example
// Write character "e" at current cursor position:
Lcd_Chr_Cp('e');
Notes

None.

Lcd_Cmd

Prototype

procedure Lcd_Cmd(out_char: byte);

Description

Sends command to Lcd.

Parameters
  • out_char: command to be sent
Returns

Nothing.

Requires

The Lcd module needs to be initialized. See Lcd_Init table.

Example
// Clear Lcd display:
Lcd_Cmd(_LCD_CLEAR);
Notes

Predefined constants can be passed to the function, see Available Lcd Commands.

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 ClipboardCopy Code To Clipboard
program Lcd_COG_2x16;

// LCD module connections
var LCD_RS : sbit  at LATB2_bit;
var LCD_EN : sbit  at LATB3_bit;
var LCD_D4 : sbit  at LATB4_bit;
var LCD_D5 : sbit  at LATB5_bit;
var LCD_D6 : sbit  at LATB6_bit;
var LCD_D7 : sbit  at LATB7_bit;

var LCD_RS_Direction : sbit at TRISB2_bit;
var LCD_EN_Direction : sbit at TRISB3_bit;
var LCD_D4_Direction : sbit at TRISB4_bit;
var LCD_D5_Direction : sbit at TRISB5_bit;
var LCD_D6_Direction : sbit at TRISB6_bit;
var LCD_D7_Direction : sbit at TRISB7_bit;
// End LCD module connections

var txt1 : array[16] of char;
    txt2 : array[10]  of char;
    txt3 : array[8]  of char;
    txt4 : array[7]  of char;
    i    : byte;                       // Loop variable

procedure Move_Delay();                // Function used for text moving
  begin
    Delay_ms(500);                     // You can change the moving speed here
  end;

  begin
    CHECON := 0x32;
    AD1PCFG := 0xFFFF;                 // Configure AN pins as digital I/O

    txt1 := 'mikroElektronika';
    txt2 := 'LV32MX v6';
    txt3 := 'Lcd4bit';
    txt4 := 'example';

    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(500);

    // Moving text
    for i:=0 to 3 do                   // Move text to the right 4 times
      begin
        Lcd_Cmd(_LCD_SHIFT_RIGHT);
        Move_Delay();
      end;

    while TRUE do                      // Endless loop
      begin
        for i:=0 to 7 do               // Move text to the left 7 times
          begin
            Lcd_Cmd(_LCD_SHIFT_LEFT);
            Move_Delay();
          end;

        for i:=0 to 7 do               // Move text to the right 7 times
          begin
            Lcd_Cmd(_LCD_SHIFT_RIGHT);
            Move_Delay();
          end;

      end;
  end.

Lcd HW connection

Lcd HW connection

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