----- Original Message ----- 
From: "Phil Cross" <pj_cross@hotmail.com>
To: <piclist@mit.edu>
Sent: Friday, September 15, 2006 5:40 PM
Subject: [PIC] - LCD module interface power-up initialization.


> There is lots of stuff on this topic, and I have looked at lots, but I
> find
> it bewilderingly inconsistent. Finally, I decided to use Microchip AN587
> as
> my guide.
>
> I have assembler programmed an 18F452 to initialize a Powertip PC1602F
> 16X2
> display, which I believe to be compatible with the HD44780. I use the
> 4-bit
> interface. I have tested it by running power-up initialization, and then
> sending a 'T'. However, it doesn't work, and I am really at a loss to know
> what is wrong.


..
Hello Phil & PIC.ers,

I've been using the self-same Powertip 1602 lcd for a number of years.
No problems, here is the intialisation segment:-


INIT_LCD ;initialise lcd, execute once only @ pup

call     DELAY_100ms
         movlw 0x03
         movwf scratch1  ;use reg as scratch iter
init_lcd1
         movlw 0x03  ;this looping per Hitachi specs to initialise
         call      lcdwrite1 ;blast out a nibble from w contents
          call     DELAY_5ms
         decfsz scratch1,same
         bra      init_lcd1
         movlw 0x02
         call      lcdwrite1
         call      DELAY_200us
         bcf      lcd_next_rs_flag ;take rs LO for cmd function set
         movlw b'00101100' ;function set. 2lines:5x10pixel:4bit tx
        call       lcdwrite2 ;blast out full byte to 8574 ->powertip
        movlw  b'00001000'
        call        lcdwrite2 ;cmd. display off
         movlw b'00001100'
        call       lcdwrite2 ;cmd. display on:cursor off:blink off
        movlw  b'00000110'
         call      lcdwrite2 ;cmd. increment cursor:no shifting
         movlw b'00000001'
         call      lcdwrite2 ;cmd. cls:reset cursor to 00
         call     DELAY_5ms
    return


Most of this should be self-explanatory.
Routine lcdwrite1 sends a nibble to the 44780,
as in:

lcdwrite1 ;send single nibble out to 8574->powertip. enter routine with w
               ;loaded  x rs rw en  n  n  n  n        ;rs+nibble preset
..
..
return

lcdwrite2 sends two nibbles.


I'd give you those routines but at the risk of just adding confusion, they 
are
written in my apps. for transmitting data over an i2c bus to the 44780.
Hope this helps.



    best regards,   John

email from the desk of John Sanderson.
JS Controls, Manufacturer & Purveyor of laboratory force testing
apparatus.
PO Box 1887, Boksburg 1460, Rep. of S. Africa
Tel / Fax: +27 11 893 4154
Cell: 082 741 6275
Web: www.jscontrols.co.za



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