Out of curiousity is your LCD 4 bit for data?

John

--- Stewart Abel <stew@stewartabel.co.uk> wrote:

> Ok, I've totally rewritten my code.  I have tried
> different length delays
> but still to no avail.  I have also tried different
> rated Pots on the
> contrast circuit, but still nothing.  Here is my new
> code, commented better
> this time!!!
> 
> 	include	p16f73.inc
> 	list p=16f73
> 	;include	XLCD.inc
> 
> 	CBLOCK 0x020
> 		Delay_i
> 		DelayCount
> 		data_to_send
> 		LCD_temp
> 	endc
> 
> 	RS	equ		4			;RS bit
> 	E	equ		5			;E bit
> 	D4	equ		0			;Data bits
> 	D5	equ		1
> 	D6	equ		2
> 	D7	equ		3
> 	LCD_PORT	equ	PORTB	;Port LCD connected to
> 	LCD_TRIS	equ	TRISB	;Tris LCD connected to
> 
>  org 0
> 	
> 	goto init
> 
>  org 4
> 
> init 	bsf 	STATUS, RP0
> 		movlw 	0x00
> 		movwf	LCD_TRIS			;Set LCD_TRIS to
> Outputs
> 		bcf		STATUS, RP0
> 		clrf	LCD_PORT	;clear LCD_PORT	
> 
> init_lcd
> 		movlw	0x014		;Delay to wait for LCD to initalise
> 		call	Dlay
> 		movlw	0x03
> 		call	send_w		;Send Reset
> 		movlw	0x05
> 		call	Dlay		;Delay 5ms
> 		movlw	0x05
> 		call	send_w		;cycle Reset
> 		call	Dlay_500us
> 		movlw	0x05
> 		call	send_w		;cycle reset again
> 		movlw	0x002
> 		call	send_w		;Set to 4 bit mode
> 		movlw	b'00101000'
> 		call	send_w_data	;Set Interface Length
> 		movlw	b'00010000'
> 		call	send_w_data	;Disable shifting of display
> 		movlw	b'00000001'	;clear display
> 		call	send_w_data
> 		movlw	b'00000110'	;enable cursor increment
> 		call	send_w_data
> 		movlw	b'00001110'	;turn display & cursor on
> 		call	send_w_data
> 
> mainline
> 		bsf		LCD_PORT, RS	;Put LCD into data mode
> 		nop
> 		nop
> 		nop
> 		nop
> 		movlw	'H'
> 		call	send_w_data
> 		movlw	'E'
> 		call	send_w_data
> 		movlw	'L'
> 		call	send_w_data
> 		movlw	'L'
> 		call	send_w_data
> 		movlw	'O'
> 		call	send_w_data
> 		goto $
> 
> Dlay	movwf	DelayCount		;Calls Dlay_1ms number of
> times
> stored in w_reg
> Dlay_loop
> 		call 	Dlay_1ms
> 		decfsz	DelayCount, f
> 			goto Dlay_loop
> 		return
> 
> Dlay_1ms
>         movlw 	0xff			;1ms Delay on 4Mhz Oscillator
>         movwf 	Delay_i
> 		goto	L1
> Dlay_500us
>         movlw 	d'156'			;aprox 500us Delay on 4Mhz
> Oscillator
>         movwf 	Delay_i
> L1	    nop
>         decfsz 	Delay_i, f
>         	goto 	L1
>         return
> 
> send_w_data
> 		movwf	data_to_send
> 		swapf	data_to_send, f
> 		movlw	0x00F
> 		andwf	data_to_send, w
> 		call	send_w
> 		swapf	data_to_send, f
> 		movlw	0x00F
> 		andwf	data_to_send, w
> 		call	send_w
> 		return
> 
> send_w	bsf		LCD_PORT, E
> 		nop
> 		nop
> 		nop
> 		nop
> 		nop
> 		nop
> 		movwf	LCD_PORT		;Sends data to LCD_PORT
> 		nop
> 		nop
> 		nop
> 		nop
> 		nop
> 		nop
> 		bcf		LCD_PORT, E
> 		nop
> 		nop
> 		nop
> 		nop
> 		nop
> 		return
> 		
>  end
> 
> stew
> 
> > -----Original Message-----
> > From: piclist-bounces@mit.edu
> [mailto:piclist-bounces@mit.edu] On Behalf
> > Of Alan B. Pearce
> > Sent: 28 June 2006 14:34
> > To: Microcontroller discussion list - Public.
> > Subject: Re: [PIC] LCD Interface HD44780
> > 
> > > Thanks for this Jinx, I will try it out.  Is
> there anything I need to
> > > change as far as timings are concerned, I am
> using a 4mhz oscillator
> > 
> > One of the queries this problem often brings up is
> the question "are you
> > really using a 44780, or one of the clones"? Many
> of the clones require
> > longer delays, especially when initialising the
> chip, and the general
> > consensus seemed to be to start with delays that
> are significantly longer,
> > and then once you have the display working,
> shorten them.
> > 
> > 
> > --
> > http://www.piclist.com PIC/SX FAQ & list archive
> > View/change your membership options at
> > http://mailman.mit.edu/mailman/listinfo/piclist
> 
> -- 
> http://www.piclist.com PIC/SX FAQ & list archive
> View/change your membership options at
> http://mailman.mit.edu/mailman/listinfo/piclist
> 


__________________________________________________
Do You Yahoo!?
Tired of spam?  Yahoo! Mail has the best spam protection around 
http://mail.yahoo.com 
-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist