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SV: [Lcdproc] HD44780 problems

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  • From: isaacsorge AT (Isaac)
  • Subject: SV: [Lcdproc] HD44780 problems
  • Date: Thu Aug 28 16:07:02 2003

For what it's worth (and if anyone cares), I fixed this by tying pin 5 (R/w)
to GND. Haven't yet tried it using the data pin for power (still on the PSU),
but hopefully this will also work.

Thanks for the help! :)


On August 28, 2003 08:45 am, Carl Nordlund wrote:
> Although I am a newbie w/ electronics, linux and lcdproc, I had a
> similar problem with one of my machines running an hd44780 lcd on my par
> port. The solution was pull-up resistors, i.e connecting a bunch of
> resistors between the datapins and GND, thus forcing the potential on
> the data pins up. Then I connected the data pins to the hd44780. This
> might be the problem here?
> /Carl
> -----Ursprungligt meddelande-----
> Från:
> lcdproc-admin AT
> [mailto:lcdproc-admin AT]
> För Isaac
> Skickat: den 28 augusti 2003 02:10
> Till:
> lcdproc AT
> Ämne: [Lcdproc] HD44780 problems
> I just bought an Optrex DMC20481 with an HD44780 controller on it; I got
> around to wiring it up today and I can't seem to get it to work right.
> I've got a pot hooked up for contrast, and only at its most-grounded
> setting
> can i see anything, and then it's just the 1st and 3rd lines filled with
> blocks. I've tried it hooked to a data pin for +5V, and i've also tried
> it
> hooked to a floppy connector. With the data pin, the voltage from Vcc to
> is 1.6V, and with the floppy connector it's 2.5V. On one of the data
> pins
> it's 4.6V, and the rest are all ~2.5V.
> My two questions are:
> a) Why is the voltage so low at the pins? I don't understand this at
> all.
> b) If the voltage was this low, would this have caused a latchup and
> fried my
> controller?
> Thanks a lot for any help,
> Isaac
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