scan alphanumeric kbd, drive approx. 160x100 LCD, update display in one chip?

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Greetings.

I would like to be able to scan an alphanumeric keyboard and drive the
bare glass of a graphic LCD display (say, 160x100 or 160x160px) in a
device that is essentially an intelligent frame buffer with a keyboard
("very thin client").

That is, the device receives display updates, either as entire frames
or as pixel deltas (changed pixels only). The latter, especially,
would need a small micro.

Since I want this to be cheap, cheap, cheap in very high volumes, I'd
like to do this in an ASIC with as much functionality as economically
justified on the one die.

Does it make economic sense to do the ASIC in a package with a
humongous number of pins (i.e. row and column scanners for the kbd and
row and column drivers for the display plus memory interface for
external RAM/ROM)? That would make over 350 pins, I would think, for
the 160x160 LCD and a 10x10 kbd matrix.

Another issue is drive voltages for the display from such an ASIC;
charge pumps, etc.

Am I nucking futs? Should I just go with a bunch of standard parts? If
so, any suggestions?

John

Re: scan alphanumeric kbd, drive approx. 160x100 LCD, update display in one chip?

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I'd guess there's pretty certainly no point in that.  Reinventing
wheels can be fun at times, but rolling your own LCD controller from
scratch doess seem excessive.

Why use a bare LCD in the first place, instead of something with at
least basic support circuitry exactly where it makes most sense, e.g.
to step a bucket-chain pulser along one edge of the LCD, and (analog)
multiplexers to drive the other?

At the minimum, you'ld end up with a lot less mechanical headaches.
At least to me, neither 320 wires of ribbon cable nor having the LCD
mounted directly on the PCB sound like clever ideas.  And that's not
counting the number of PCB layers you'ld need to safely route 320
lines to two fine-pitched panel connectors of 160 pins each.

Not if you can have a nice standardized panel link using something
like 6 wires and a standard memory-mapped LCD controller frame buffer
instead without having to go ASIC for that.

--
Hans-Bernhard Broeker ( snipped-for-privacy@physik.rwth-aachen.de)
Even if all the snow were burnt, ashes would remain.

Re: scan alphanumeric kbd, drive approx. 160x100 LCD, update display in one chip?

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I'd rather think of a LCD with shift register / buffer chips (like KS0086),
and drive the much narrower serial channel with a micro or ASIC - drops the
pin count appreciably and does not need a high-voltage process. A bare panel
needs 260 to 320 pins with peculiar high-voltage drive.

Tauno Voipio
tauno voipio @ iki fi



Re: scan alphanumeric kbd, drive approx. 160x100 LCD, update display in one chip?
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You need to define 'very high volumes'

 > I'd like to do this in an ASIC with as much functionality as economically
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Why ?

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Think about how many layers will that make the PCB ?

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Stick with proven parts, and work the design in stages.
First get it working, then ramp volumes using that, then as the
market indicates it really does want your widget, work to reduce the
total manufactured price.
  A good display sector to focus on, would be cell phone Chip-on-glass
solutions. This is likely to dominate your BOM anyway.
  They really ARE very high volumes, (so you 'piggy back' on someone
elses production/factory tooling ) and will also slash your pin counts.
  You might then even get the widget onto 2 or even 1 layer PCB !

-jg




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