[sdiy] FPGA digital audio

[Magnus Danielson]

From: patchell <patchell at silcom.com>
Subject: Re: [sdiy] FPGA digital audio
Date: Sat, 05 Jan 2002 17:51:38 -0800

> 
> 
> harry wrote:
> 
> > Since it was my first design, I had the luxury of an experienced engineer, who
> > looked at my design and assured me the smallest available FPGA was more
> > than big enough.
> >
> > I learned the syncronous design the hard way... after having the design fail to
> > work as suggested in the simulation.  I also found that straight decoding using
> > and gates (etc) worked very well. In the "real world" you would never do it that
> > way... for the board space you'd burn up.
> 
>     Actually, it is amazing how in the gate array, things you would do with IC's to
> save board space actually use up more gate array realestate.  After I had completed
> my first design, and got it working, I read some document that Xilinx had on how the
> router worked with the gate array and it had lots of suggestions on how to save
> space.  After following the suggestions from the Xilinx literature, I was amazed
> that I gained about 5% or so.  Sometimes, what looks redundent on the schematic end
> up using fewer resources.

Indeed. All this is the tricks of trade, but the situation is
different and therefore you have to learn new tricks. What is "the
right thing" in one way can be really about the worst things you can
come up with in another situation.

There is a learning curve to become really efficient in craming out
the most of an FPGA. But you don't have to learn *that* much to start
enjoying working with them. If you do not attempt to pump them full,
if you are not attempting to use them to the limit of their marked
speed, then it can be pretty painless. Also, if you do your homework
by simulation upon simulation with testbenches, you have improved upon
your way of designing.

I actually took my experience with testbenching modules in VHDL over
to my software work, and boy did the quality of code improve?

You can learn alot by the assumed methods of working...

Cheers,
Magnus