> I've had a hard time getting my 320x200 graphics display with
> the Seiko SED1335 chipset to work.

What is it doing / not doing?

Is it just giving you a blank screen (update frequency and/or contrast
voltage magnitude or polarity problems) scrolling band on the display
(system setup problem), or is the screen blank or filled with garbage but
stable (if it is, you're nearly there!)?

> I'm using an F84 with an i2c port expander
> (Philips PCF8574) for the 8-bit data bus (at least the i2c
> stuff is working
> even if the display isn't :) ) and 3 I/O pins for read, write
> and address.

I've only used it with an 8051-core controller, but assuming that bit is
timing the bus correctly, it should be similar.  IIRC, there was a pin to
set for different processor interfaces, check you have the correct option
(I think it set whether there were separate RD and WR pins or all on one
pin.  What stage have you got to with it, do you have logic analysers etc
available, or a 'scope?  If it's doing the scrolling band, check the sync
outputs to the LCD, see if they change frequency when you run your startup
code.

If the sync outputs don't change frequency, either your setup is very close
to the power up settings, or, more likely, your processor isn't talking to
the controller.

My design was on a 192x192 then moved to a 320x240 display, I worked
through the formulae in the documentation to get the various settings.  In
the setup command, screen width is calculated in characters, (0x28 = 40
chars = 320 pixels for visible width, try 0x2C = 44 for addressable width),
and height is in pixels, 0xC8 = 200 pixels).

> The Seiko documentation wasn't very helpful for me. They even had a
> pseudo-code example but it didn't help either (my brain must
> be fried).

The documentation is a bit obscure, and it took me a while to get going
first time.  Once all the system set parameters were working, the rest was
straightforward.

> you have any code (even just a snippet showing
> initialization) that you can share?

No, sorry, I used the 1335 in my last job, which I left about a month ago,
I can still remember snippets of it though...

Nigel
--
Nigel Orr, Design Engineer                     nigel@axoninstruments.co.uk
Axon Instruments Ltd., Wardes Road, Inverurie, Aberdeenshire, UK, AB51 3TT
              Phone: +44 1467 622 332   Fax: +44 1467 625 235
                      http://www.axoninstruments.co.uk

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