Lcd Library

The mikroBasic 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 creating a set of custom Lcd characters use Lcd Custom Character Tool.

Library Dependency Tree

External dependencies of Lcd Library

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

Lcd_Init

Prototype	sub procedure 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 module connections dim LCD_RS as sbit at PORTD2_bit LCD_EN as sbit at PORTD3_bit LCD_D7 as sbit at PORTD4_bit LCD_D6 as sbit at PORTD5_bit LCD_D5 as sbit at PORTD6_bit LCD_D4 as sbit at PORTD7_bit dim LCD_RS as sbit at DDD2_bit LCD_EN as sbit at DDD3_bit LCD_D7 as sbit at DDD4_bit LCD_D6 as sbit at DDD5_bit LCD_D5 as sbit at DDD6_bit LCD_D4 as sbit at DDD7_bit ' End Lcd module connections ... Lcd_Init()

Lcd_Out

Prototype	sub procedure Lcd_Out(dim row as byte, dim column as byte, dim byref text as string)
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	sub procedure Lcd_Out_Cp(dim byref text as 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!")

Lcd_Chr

Prototype	sub procedure Lcd_Chr(dim row as byte, dim column as byte, dim out_char as byte)
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	sub procedure Lcd_Chr_Cp(dim out_char as byte)
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	sub procedure Lcd_Cmd(dim out_char as byte)
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

program  Lcd_Test

' LCD module connections
dim LCD_RS as sbit at PORTC2_bit
dim LCD_EN as sbit at PORTC3_bit
dim LCD_D4 as sbit at PORTC4_bit
dim LCD_D5 as sbit at PORTC5_bit
dim LCD_D6 as sbit at PORTC6_bit
dim LCD_D7 as sbit at PORTC7_bit

dim LCD_RS_Direction as sbit at DDC2_bit
dim LCD_EN_Direction as sbit at DDC3_bit
dim LCD_D4_Direction as sbit at DDC4_bit
dim LCD_D5_Direction as sbit at DDC5_bit
dim LCD_D6_Direction as sbit at DDC6_bit
dim LCD_D7_Direction as sbit at DDC7_bit
' End LCD module connections

dim txt1 as char[17]
    txt2 as char[10]
    txt3 as char[9]
    txt4 as char[8]
    i    as byte                      ' Loop variable

sub procedure Move_Delay()            ' Function used for text moving
  Delay_ms(500)                       ' You can change the moving speed here
end sub

main:
    txt1 = "mikroElektronika"
    txt2 = "EasyAVR6"
    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                      ' Move text to the right 4 times
      Lcd_Cmd(_LCD_SHIFT_RIGHT)
      Move_Delay()
    next i

    while TRUE                        ' Endless loop
      for i=0 to 6                    ' Move text to the left 7 times
        Lcd_Cmd(_LCD_SHIFT_LEFT)
        Move_Delay()
      next i
      for i=0 to 6                    ' Move text to the right 7 times
        Lcd_Cmd(_LCD_SHIFT_RIGHT)
        Move_Delay()
      next i
    wend
end.

Lcd HW connection

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