Re: LCD module - PC Parallel port



>>
> I don't know if the parallel port wired correctly, but the resistor
> on pin 3 of the LCD should be a 10k pot, wired between +5 and GND
> and the center of the pot to pin 3 of the LCD. Right now you have a fixed
> contrast and you want it variable.
> rw

rw is right,
and this could be a contender for the '16-black boxes', the
contrast is too high. Have you used the circuit with the pot (incorrectly
wired in the diagram as rw has already mentioned), or the circuit without
the pot. My recommendation...you need the pot (not all LCDs behave the same
in my experience).

Also, how did you measure the 0V level?. Did you measure it when the PC was
attempting to write to the display? or did you measure it when the PC was
idle?. If you have a scope it would be better to capture a data burst and go
from there.

Don't shoot me down, but you did measure the data port signal with respect
to your parallel port 0V and you have connected the parallel port 0V to your
5V supplys 0V? It doesn't show this connection on the schematic. If you are
using an isolated 5V supply (a battery?), then you do need to connect the
parallel port 0V to your 5V supply 0V line.

Jim
www.picmodules.com



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Relevant Pages

  • Re: LCD module - PC Parallel port
    ... on pin 3 of the LCD should be a 10k pot, wired between +5 and GND ... but you did measure the data port signal with respect to your parallel port 0V and you have connected the parallel port 0V to your 5V supplys 0V? ...
    (comp.arch.embedded)
  • Re: LCD module - PC Parallel port
    ... on pin 3 of the LCD should be a 10k pot, wired between +5 and GND ... but you did measure the data port signal with respect to your parallel port 0V and you have connected the parallel port 0V to your 5V supplys 0V? ...
    (comp.arch.embedded)
  • Re: LCD module - PC Parallel port
    ... on pin 3 of the LCD should be a 10k pot, ... but you did measure the data port signal with respect to your parallel port 0V and you have connected the parallel port 0V to your 5V supplys 0V? ...
    (comp.arch.embedded)
  • Re: LCD module - PC Parallel port
    ... Have you used the circuit with the pot ... > any of the Green pins on the printer port is GND. ... The problem was solved when I connected parallel port GND to +5V power ...
    (comp.arch.embedded)
  • Re: LCD module - PC Parallel port
    ... I've wired up the LCD module to the Parallel Port of PC as shown here: http://www.codeproject.com/csharp/cspplcds.asp ... Signals on Parallel port is working fine. ... on pin 3 of the LCD should be a 10k pot, ...
    (comp.arch.embedded)