[sdiy] Multiple LCD connection sanity check please

[Mike Pepper]

> You could save some time by having separate delay counters for each
> dispay in your background process, so the wait periods can be in parallel.
>
> In other words, if display A is waiting, you don't have to block display
> B too until A is ready. Would probably need separate FIFOs for
> each display however, otherwise it may get confusing to find out what's
> still left to send.
>
> Chris
>
>
>
> On Tue, 11 Jan 2011 15:51:27 +0000 Neil Johnson
> <neil.johnson97 at ntlworld.com> wrote:
>
> > Hi Tom,
> >
> > > I'm ok with that. Following advice I received here in the past, I've
written a buffered LCD output routine. You can stuff long messages into a
buffer, and then a background task sends a character to the LCD every 0.5mS.
The only clever bit is that you can also send delays to the LCD buffer,
which makes it easy to deal with LCD commands that take more than a single
0.5mS time period.
> >
> > Well, if you have lots of displays then you'll presumably have lots of
> > data to display on them?  In which case 2000 bytes/s may not be fast
> > enough.  In principle you can send characters to the LCD drivers in
> > sub 100us.  Some commands take longer (RETURN is typically >1ms).
> >
> > > Failing that (simply paralleling them all up) I guess I'd be looking
at adding a tristate buffer between the LCD inputs and the bus, would I?
> >
> > You could probably get away without using tristate buffers, unless
> > these were hanging off a system data bus.  I don't think that's the
> > case here though.
> >
> > > Well, 6 or 8 would be nice. Shall I give it a whirl and let everyone
know how I get on?!
> >
> > I guess it all boils down to your specific application, so yes do try
> > it and let us know!
> >
How about using a simple PIC as an I2C to parallel tranceiver for each
display. It could also buffer the writes, and even take care of pwer-on
intialisation. That way you could just write the data to the PIC's RAM, and
let it take care of the updating. You then reduce your panel wiring
problems, and you'd be using multiple instances of the same code at
different addresses. I guess the PIC module would be a re-usable desgn too.

Just a thought

||\/||ike