Re: [lcd4linux] Data pins seem to be shorted on HD44780

[Aaron K. <aar...@ro...>]

Hi Michael;
Oooh quick reply here :)
Test screen does mean the alternating black bars...and yeah i had fun
when i first connecting this thing to the power wondering why i couldn't
see anything.
As for the wiring the pins go 1-16 and are label with text like Vss Vdd
DB5...etc so unless they printed the thing wrong.
And the flashback light is a symptom but it is kind cool.
 as for what happens when i run lcd4linux:

root@linux:~# lcd4linux -Fvv
Version 0.10.1-CVS starting
plugin_cfg.c: Variable minute = '60000' (60000)
plugin_cfg.c: Variable tack = '100' (100)
plugin_cfg.c: Variable tick = '500' (500)
lcd4linux.c: initializing driver HD44780
HD44780: using model 'generic'
HD44780: using parallel port
HD44780: using 1 Controller(s)
HD44780: using 8 bit mode
HD44780: using ppdev /dev/parport0
HD44780: wiring: DISPLAY:RS        - PARPORT:INIT   (Pin 16)
HD44780: wiring: DISPLAY:RW        - PARPORT:AUTOFD (Pin 14)
HD44780: wiring: DISPLAY:ENABLE    - PARPORT:STROBE (Pin  1)
HD44780: wiring: DISPLAY:ENABLE2   - PARPORT:GND
HD44780: wiring: DISPLAY:ENABLE3   - PARPORT:GND
HD44780: wiring: DISPLAY:ENABLE4   - PARPORT:GND
HD44780: wiring: DISPLAY:BACKLIGHT - PARPORT:GND
HD44780: wiring: DISPLAY:GPO       - PARPORT:GND
HD44780: using busy-flag checking
initializing layout 'Default'
lcd4linux.c: starting main loop
lcd4linux.c: got signal 2
lcd4linux.c: leaving main loop
HD44780: shutting down.

Thanks again
Aaron

On Sun, 2006-25-06 at 20:38 +0200, Michael Reinelt wrote:
> Hi Aaron,
> 
> > FIrst off here is my LCD info:
> > it is a HD44780 (or compatible) 20x4 backlight display from:
> > http://cgi.ebay.ca/HD44780-characte...QcmdZ ViewItem
> This link does not work...
> 
> > Basically the problem is that all the data pins seem shorted...sort
of.
> > I get the the test screen okay when i connect the power. But if i
don't
> > connect the power and just have the parallel port connected and the
> > backlight turned on (i put a swtich in) the backlight kinda flashes.
> > What i eventually figure out is that somehow and signal being sent
along
> > the data pins is being sent to the 5+ pin for the controller which
> > shares a [ath with the backlight so it causes the backlight to
flash. As
> > well there is a non-inf resistance between the data pins and the +5v
pin
> > (about 3 k one way (with +data pin and -the 5+ pin) and 20k the
other
> > way)
> 
> The resistance look fine to me. As for the flashing backlight... I've
> never tried it this way.
> 
> Are you sure you're using the correct wiring? I've seen displays where
> the pins are not 1-2-3..14-15-16, but 15-16-1-2-3...13-14!
> 
> What do you mean by "test screen"? alternating black/white bars? Then
> the display should be ok, and it means that your contrast voltage is
in
> a reasonable range (don't ask how much hours I've spent looking for
> bugs, when everything was fine, but due to wrong contrast settings I
was
> unable to see the display running correctly :-) (Sam, are you
listening?
> SCNR)
> 
> What happens if you connect everything and run lcd4linux?
> 
> 
> bye, Michael
>