Re: Multiple CPLDs on a PCB.

NickNitro wrote:
Hi,

Apologies if this isn't the best group, but there doesn't appear to be
a comp.arch.cpld group.

I'm going to start learning about CPLDs to use them in my projects,
but the algorithm I've developed will require a few CPLDs working on
different parts of the algorithm in sequence. So part A of the
algorithm may require 5 CPLDs, part B 8 CPLDs and part C 3 CPLDs.

Probably not the best direction.

They
are all complete guesses at the moment, as I know next to nothing
about PLDs in general, but I know that for my algorithm to run as fast
as required, I will require multiple PLDs. I'm choosing CPLDs as from
what I've read FPGAs can be a bit overbearing for a beginner due to
the amount of features/number of gates they have,

You do not have to use all features on the first pass :)

also CPLDs have more predictable timing?

On simple designs, yes. As multiple CPLDs get into the frame, it gets
harder.


So, I'm wondering just how difficult using multiple CPLDs on a custom
PCB actually is? I'm sure it's achievable, but I would like to know
how difficult this could be.

The real fish-hook comes, when you find "Part B" really needed 9 devices!

Also, could any simulators be used to
simulate a complex design with multiple CPLDs on a PCB?

Not easily. You _could_ have two designs, one that is partitioned
into the smaller blocks, and another that is the whole system.
The whole system one would simulate - but you may have spotted by
now, that such a whole systemm design, is a FPGA design flow :)

Finally, could
anybody recommend any books for getting started in the CPLD world -
I'm unsure to use Verilog or VHDL at the moment?

Download the development tools, and try some code in each.
Search for come examples close to what you want to do.
The tools can target BOTH cpld, and FPGA (& both languages),
so you can actually get quite advanced in the design, before you commit to a PCB design. (or even a final device)

There are also cross-over CPLDs like MAX II and MachXO, and
also the FLASH FPGAs from Actel and Lattice to look into.

Give a short list if what your design needs to do, and someone here
might suggest a device family, and an expected speed range.

-jg


.

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