DIY Digital Synth

[jbv]

>
>
>     Designing what goes inside of the FPGA is actually not _too_ hard.  I have done
> quite a few Xilinx designs and am just starting to use Altera.  In both cases the design
> can be entered either as a schematic or in some sort of HDL, or both.  If you have done
> logic design in the past, the FPGA will be a breeze.  Plus, the major vendor also has
> some sort of logic blocks or mega functions that will allow you to plop down a 16x16
> muliplier or 24 bit adder into your design which really makes things a lot easier.  In
> my opinion the hardest part of doing an FPGA design is getting the data into the part
> and hooking it up.  Testing can be a bit of a drag too, since there is not way to clip a
> scope probe anywhere you want in the design.  Altera and Xilinx both supply a simulator
> so that you can debug the design, although the altera simulator has some limitations,
> but there are ways to deal with it.
>

Your remarks confirm the feeling I had after reading both Xilinx & Altera datasheets
and application notes.

I think I also remember reading somewhere that getting large internal data buses
(24 bits or more) between blocks can be a bit tricky...
And what about having large amounts of ROM & RAM in the design (I mean : not
as external chips, but inside the FPGA design) ?
And is it easy to get a pipe-line structure ? Are basic blocks latched ?

I guess another tricky step is to choose the right chip to work with, since the offer
of each company seems quite large...

And could you tell us a bit more about cost ? And what about integrating the
FPGA chip in some larger circuitry once it's programed ?

I really hope my questions aren't a drag...

Thanks in advance...

jbv