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SV: [Lcdproc] HD44780 problems


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  • From: carl AT demesta.com (Carl Nordlund)
  • Subject: SV: [Lcdproc] HD44780 problems
  • Date: Thu Aug 28 11:47:01 2003

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-----
Fr=E5n:
lcdproc-admin AT lists.omnipotent.net
[mailto:lcdproc-admin AT lists.omnipotent.net]
F=F6r Isaac
Skickat: den 28 augusti 2003 02:10
Till:
lcdproc AT lists.omnipotent.net
=C4mne: [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=20
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=20
hooked to a floppy connector. With the data pin, the voltage from Vcc to
GND=20
is 1.6V, and with the floppy connector it's 2.5V. On one of the data
pins=20
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=20
controller?

Thanks a lot for any help,

Isaac

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