I'd love to use 8-bit mode, but I'm out of pins on the PIC!

> -----Original Message-----
> From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On
> Behalf Of Jesse Lackey
> Sent: Sunday, June 10, 2007 5:05 PM
> To: Microcontroller discussion list - Public.
> Subject: Re: [PIC] Interfacing to a Hitachi 44780 LCD in 4-bit mode
> 
> Hello, two comments / questions for you...
> 
> I'm not sure if it is the same LCD driver chip, but the one in an LCD
> from Lumex I used on this project:
> http://www.celestialaudio.com/MC9S12NE64/index.html
> had so many problems in 4-bit mode that I gave up and used it in 8-bit
> mode.  I discuss this a little on the webpage.
> 
> So if possible, for starters anyway, can you switch to 8-bit mode to
> eliminate that source of possible error?
> 
> Secondly, is there a "dimming voltage" on the LCD you are using?  The
> lumex datasheet spec and schematic were given in an unclear way and
> tripped me up.  So for awhile I was doing everything right but no
> display b/c I had that voltage wrong.
> 
> Good luck to you.  I was not happy about the problems I had with this
> LCD as well.
> 
> J
> 
> 
> 
> Matthew Mucker wrote:
> > All,
> >
> > I've been debugging this problem for weeks and haven't found where my
> error
> > is, so I'm turning to the list for help. I'm trying to drive a
> Hitachi 44780
> > LCD module in 4-bit mode from a PIC chip.
> >
> > I have my PIC 16F628 connected to the LCD module as follows:
> >
> > RB4 --> LCD_E
> > RB3 --> LCD_RS
> > RA0 --> LCD_D4
> > RA1 --> LCD_D5
> > RA2 --> LCD_D6
> > RA3 --> LCD_D7
> >
> > I have tested each of these outputs and verified that I can write a
> logic
> > '1' or '0' and get the expected voltage.
> >
> > I've used Myke Predko's page (www.myke.com/lcd.htm) as my main
> reference.
> >
> > According to MPLAB SIM, my code is writing the following when the
> LCD_E line
> > is blipped:
> >
> > 			LCD
> > 			DATA	LCD
> > TIME			7654	RS	notes
> >
> > 0			0011	0	send 0x03, wait 5msec
> > 5.1964		0011	0	send 0x03, wait 160 usec
> > 5.5218		0011	0	send 0x03 a third time, wait 160
usec
> > 5.8472		0010	0	Enable 4-bit mode (following
commands are
> > two nybbles)
> > 6.0126		0010	0
> > 6.1766		1000	0	00101000: 4-bit mode, 2 line
display, 5x7
> > font
> > 6.3248		0000	0
> > 6.5068		1000	0	00001000: disp. Off, cursor off,
blink
> off
> > 6.6730		0000	0
> > 6.8370		0001	0	00000001: clear display, wait
> > 12.0356		0000	0
> > 12.1996		0110	0	00000110: increment cursor/no shift
> > 12.3658		0000	0
> > 12.5298		1100	0	00001100: display on, cursor off,
blink
> off
> > 12.6968		0000	0
> > 12.8608		0010	0	00000010: home cursor
> > 18.0618		0101	1
> > 18.2258		0111	1	Letter 'W', first character to be
> displayed
> >
> > The LCD doesn't seem to initialize and for sure my characters aren't
> being
> > displayed. I'm getting quite frustrated with this project. I'm hoping
> > someone out there can spot the error of my ways for me and help me
> get back
> > on the straight and narrow.
> >
> > Thanks,
> >
> > -Matt
> >
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