Since version mios_v1_5b [[http://www.ucapps.de/mios.html|MIOS]] has supported 4-bit mode for HD44780 compatible displays\\

Usually this mode isn't needed, but some displays have been internally configured for 4-bit operation and don't have all the necessary connections for full 8-bit operation or You might have some other reason to try this mode out.

To configure [[http://www.ucapps.de/mios.html|MIOS]] application to use 4-bit CLCD mode, changes need to be made to the application:\\

First locate\\ **'USER_Init'** section of the source files ((usually in 'main.asm', in MB_SID 'sid_init.inc'))

Then add to its own section just below the 'USER_Init' ((Don't add it in between the initialization commands or you can break something this way)):

 
       ;; use a CLCD, E input of first CLCD at D.7, E of second CLCD @C.4
       ;; using the 4-bit interface:
       ;; -> connect MBHP_CORE:J15:D7-D4 of the core module to D7-D4 of the LCD
       ;; -> left MBHP_CORE:J15:D3-D0 of the core module open!
       ;; -> tie D3-D0 of the LCD to ground
       movlw   0x37 | 0x80     ; E1: D.7, 4bit interface
       movwf   MIOS_PARAMETER1
       movlw   0x24 | 0x80     ; E2: C.4, 4bit interface
       movwf   MIOS_PARAMETER2
       movlw   0x00            ; LCD type 0
       call    MIOS_LCD_TypeSet''

Then you have to Compile the modified application.

See the comments ((marked with ;; in the beginning of the line)) in the code for how to connect the display to the core. In the display side, having the datasheet for it helps a lot.

More: [[http://www.ucapps.de/mios_fun.html#MIOS_LCD_TypeSet|MIOS function reference]]