LCD_IO 4 Example

This is a connection mode 4 Driver to demonstrate LCD features. This for the 16F877A, but, it can easily be adapted for other microcontrollers.

A 2 by 16 LCD is assumed.

    #chip 16F877A,20

    'Use LCD in 4 pin mode and define LCD pins
    #define LCD_IO 4          ' <<< the constant that selects 4-bit connection mode
    #define LCD_RW PORTE.1
    #define LCD_RS PORTE.0
    #define LCD_Enable PORTE.2
    #define LCD_DB4 PORTD.4
    #define LCD_DB5 PORTD.5
    #define LCD_DB6 PORTD.6
    #define LCD_DB7 PORTD.7
    #define LCD_WIDTH 16                ;this example assumes a 16-character-wide LCD; the library default is 20

    ;----- Main Program

    do forever

            Print "GCBASIC 2021"
            wait 3 s
            CLS

    loop
    end

Key line: #define LCD_IO 4 — selects the 4-bit parallel connection mode, which requires LCD_RS, LCD_RW, LCD_Enable, and only the upper four data lines (LCD_DB4 through LCD_DB7) to be wired to the microcontroller.

See Also:

  • LCD_IO 4 — full reference for this connection mode
  • LCD_WIDTH — setting the display width, as used above
  • LCD_IO 8 Example — the 8-bit parallel equivalent
  • LCD_IO 2 Example — a shift-register based alternative needing fewer pins
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