From: "Dzidek" <dzidek AT posejdon DOT wpk DOT p DOT lodz DOT pl> (NOSPAM)
To: <paul@pjrc.com>
Subject: LCD with Paulmon 2.1 (2.2) ?
Date: Sat, 8 Sep 2001 13:16:23 +0200

Hello.

I send You, as I promissed, Schematic and LCD procedures for PAULMON 2.1
( I call it 2.2).  I will be glad(?) if you put this in your page (send
me adress if you do it) and write who write this.

I know that many peoples visit your page( I think), so they can read and
use my concept.

My eanglish is not strong enought so please forgive me.


Information(for HTML page) :
--------------------------

Schematic for interface to LCD (HD 44780) --- >schematic1.jpg
Procedures ----> LCD.txt


  This schematic can be seen with the following URL:
  http://www.pjrc.com/tech/8051/contrib/Dzidek_Schematic.jpg


I wrote this procedures and put it in 8051 chip (Atmel). In 4 kB is
enought space to put it. So my Paulmon write some text on power-up. If
enybody want this version, compiled or *.asm, please contact me.

Interface and Procedures was written by:

Ogest    (unknown e-mail)
Rad     (xdzidek@wp.pl)



----------------------------------------------------------------------

> I am a bit concerned about your circuit.  I connected an address
> pin to R/W instead of the WR signal, because the timing diagrams
> I found specified that there was a 40 ns setup time required from
> R/W signal becoming stable to the rising edge of E.  Three NOR
> gates, using a 74HC02 might provide enough delay, but I believe
> the "typical" delay is less than 10 ns for many 74HC02 chips.

Yes, the delay is a bit problem but I use slow (very slow) 7402 chip.
It was not tested on HC or HCT chips.

----------------------------------------------------------------------



;$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
;LCD Procedures
;$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
;		Lcd_int	-LCD Init
;		Lcd_Wc	-Write Command to LCD
;		Lcd_Wd	-Write Data to LCD
;		Lcd_Busy	-IS Busy ?
;		Lcd_Wt	-Send Text to LCD
;		Clr_Scr	-Clear LCD

;*****************************************************************
lcd_int:	mov 	r7,#30			; inicjalizacja wyświetlacza
		lcall	delay_ms
		
		mov	a,#38h
		mov	dptr,#lcd_i
		movx	@dptr,a

		mov	r7,#9
		lcall	delay_ms

		movx	@dptr,a

		mov	r7,#9
		lcall	delay_ms


		movx	@dptr,a

		mov	a,#06h
		lcall	lcd_wc

		mov	a,#0ch
		lcall	lcd_wc

		mov	a,#01h
		lcall	lcd_wc
		ret
;*****************************************************************
lcd_wc:	push	dph
		push	dpl
		mov	dptr,#lcd_i		; wysłanie komndy do wyświetlacza
		lcall	lcd_busy
		movx @dptr,a
		pop	dpl
		pop	dph
		ret
;*****************************************************************
lcd_wd:	push	dph
		push	dpl
		lcall	lcd_busy		;wysłanie danych do wyswietlacza
		mov	dptr,#lcd_d
		movx	@dptr,a
		pop	dpl
		pop	dph
		ret
;*****************************************************************
lcd_rc:		
		lcall	lcd_busy	;pobranie pozycji kursora z wyświetlacza
		mov	dptr,#lcd_i
		clr 	a
		movc	a,@a+dptr
		ret
;*****************************************************************
lcd_busy:	
		push	acc		;sprawdzenie flagi busy

test_b:	clr	a
		mov	dptr,#lcd_i
		movc 	a,@a+dptr
		jb	acc.7,test_b
		pop	acc
		ret
;*****************************************************************
lcd_wt:	lcall	clr_scr
		mov	r1,#0
w:		mov	a,r1
		movc	a,@a+dptr
		jz	text_end
		lcall	lcd_wd
		inc	r1
		cjne	r1,#16,w
		mov	a,#0c0h
		lcall	lcd_wc
		sjmp	w
text_end:
		ret

;*****************************************************************

clr_scr:	mov	acc,#01
		lcall	lcd_wc
		ret

;*****************************************************************
delay_ms:	;daje opoznienie 0.5 ms * r7 przy zegarze 11 mhz	
a00:		mov	r6,#229d
		djnz	r6,*
		djnz	r7,a00
		ret