Hi Robert,
I have tried this code. Use 16x2 character LCD, 4 bit mode, use RA3-0 to LCD.
It is success.

Note : Be carefull for the delay. It uses maximum delay, because it does not
read the flag (read mode).

;///////////////////////////////////////////////////////////
;***********************************************************
;  LCD Initialization
;***********************************************************
LCD_initialization
  call    Dlay5                  ;  Wait 20 msecs before Reset
  call    Dlay5
  call    Dlay5
  call    Dlay5
;----------------------- once 4 bit ---------------------
  bcf  STATUS,C
  movlw       0x03                    ;  Reset Command (data was in 'W')
  call          NybbleOut               ;  Send the Nybble
  call          Dlay5    ;  Wait 5 msecs before Sending Again

  bcf          STATUS,C
  movlw      0x03
  call          NybbleOut               ;  Send the Nybble
  call          Dlay160                   ;  Wait 160 usecs before Sending the
Third Time

  bcf          STATUS,C
  movlw      0x03
  call          NybbleOut               ;  Send the Nybble
  call          Dlay160                   ;  Wait 160 usecs before Sending the
Third Time

  bcf           STATUS, C
  movlw       0x02                    ;  Set 4 Bit Mode
  call           NybbleOut
  call           Dlay160

;----------------------- twice 4 bits --------------------
  movlw 0x028                    ;  Note that it is a 2 Line Display
  call SendINS

  movlw 0x008                    ;  Turn off the Display
  call SendINS

  movlw 0x001                    ;  Clear the Display RAM
  call SendINS
  call    Dlay5


  movlw 0x006                    ;  Enable Cursor Move Direction
  call SendINS

  movlw 0x00C                    ;  Turn the LCD Back On
  call SendINS

  return

Regards,
Harry Febianto


"Robert A. LaBudde" wrote:

> I have to admit I'm confused about how to interface to a Hitachi 44780
> controlled LCD via 4-bits.
>
> I've got a number of sample programs from books and websites, and there
> doesn't appear to be a unanimity on how to accomplish initialization of the
> LCD.
>
> The most common initialization sequence is (after 15 ms startup delay):
>
> 1. Send 0x'3' (8-bit interface, 1/2 of command)
> 2. Wait > 4.1 ms
> 3. Send 0x'3'
> 4. Wait 100 us
> 5. Send 0x'3'
> 6. Wait 100 us
> 7. Send 0x'2' (4-bit interface)
> 8. Wait 40 us
> 9. Send 0x'28 (4-bit interface, 2-line)
> 10. Wait 40 us.
>
> When I try this sequence with my 20 x 4 display, it doesn't reliably
> initialize. So I went to the 44780 controller specification from the
> Hitachi website, and I found that they recommended the following sequence
> (after the 15 ms startup delay):
>
> 1. Send 0x'2'. (4-bit interface, 1/2 of command)
> 2. Wait 40 us.
> 3. Send 0x'28' (4-bit, 2-line)
> 4. Wait 40 us.
>
> This sequence initializes the LCD reliably. It also makes sense, since the
> 0x'2' command would be logically interpreted by the controller as a switch
> to 4-bit mode. Then the 0x'28' would be executed completely.
>
> My question is: What's with the extraneous three 0x'3' commands recommended
> and used by others? Why are these even hypothetically necessary, since the
> controller comes up in 8-bit mode by default anyway?
>
> ================================================================
> Robert A. LaBudde, PhD, PAS, Dpl. ACAFS  e-mail: ral@lcfltd.com
> Least Cost Formulations, Ltd.                   URL: http://lcfltd.com/
> 824 Timberlake Drive                            Tel: 757-467-0954
> Virginia Beach, VA 23464-3239                   Fax: 757-467-2947
>
> "Vere scire est per causae scire"
> ================================================================