[En-Nut-Discussion] Ideas from an outsider

Don Ingram don at led.com.au
Sat Nov 2 22:29:17 CET 2002

Just to further complicate the discussion...

Instead of using discrete or CPLD why not FPGA.  The devices are dirt cheap
& there are free Xilinx tools available.  A good example of the approach
which would be applicable is the Tiger addon from Ed at JED.

The Tiger modules are programmed in Basic ( yeech ) but the data for the
FPGA is stored in the basic program & downloaded at system boot. This both
eliminates the separate EEPROM and also allows the user to keep with the
basic program downloader for the Tiger family.

The FPGA is able to be reconfigured to carry out quite complex functionality
well beyond just address decoding. The additional hardware cost is
negligible ( < $3 ).  The learning curve is considerable to get a handle on
the Xilinx tools but the end result is extremely versatile & very powerful.

This is the very reason as to why the field has taken off. It allows a bunch
of devices to be stuck on the board & the logic with all its little extra
delays, gotchas and so on to be worked out later in software instead of
additional PCB runs. It also opens an entirely new field of enut
development, that is, addon VHDL modules for high speed counters, encoders,
DSP, CRC generation, HDLC etc.  Most manufacturers are providing code for
simple processors to run within their FPGA's


Don Ingram

----- Original Message -----
From: "Austin Schutz" <tex at off.org>
To: <en-nut-discussion at egnite.de>
Sent: Thursday, October 31, 2002 9:14 AM
Subject: Re: [En-Nut-Discussion] Ideas from an outsider

> On Thu, Oct 31, 2002 at 08:57:31AM +1000,
peter.scandrett at transport.alstom.com wrote:
> > Harald,
> >
> > This may sound like heresy, but what about laying out 2 (or even 3)
> > options. That is layout can handle a gates version, and at least one
> > version. By carefully choosing a CPLD pin-out common to several
> > manufacturers and product ranges, you may be able to get the best of
> > worlds.
> >
> You guys with your good cpld/whatever ideas should submit schematics
> and patches.
> To make it worthwhile whatever the solution is should be:
> a. Flexible
> b. Easily programmable without extra hardware tools
> c. Configurable with included or freely available software
> d. Understandable by those of us lacking experience
> Show us the money :)
> Austin
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