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SV: [Lcdproc] HD44780 problems

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  • From: carl AT (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?


-----Ursprungligt meddelande-----
lcdproc-admin AT
[mailto:lcdproc-admin AT]
F=F6r Isaac
Skickat: den 28 augusti 2003 02:10
lcdproc AT
=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
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
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
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
b) If the voltage was this low, would this have caused a latchup and
fried my=20

Thanks a lot for any help,


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