Re: USB programmable Open Source Hardware

On Sep 29, 3:40 am, rickman <gnu...@xxxxxxxxx> wrote:
Yes, that is true, but not my point.  A single ground plane does
nothing to reduce noise on the power rails.  The capacitor that is
formed by parallel planes spaced 10 mil in a PWB is the best power
supply decoupling device you can provide.  Even on a very small board,
these planes provide significant noise elimination, both in terms of
minimizing the effect on the chips and also in terms of reducing
EMI.

I realize that many designs just don't have a need for this, but my
point was that a general purpose development/eval board needs to
consider a wide range of designs including ones that push the speed of
the device and have a number of outputs switching at high edge rates.
Capacitors alone will not normally address the problem adequately in
these cases.

I'd generally agree - a demoboard such as this, should not be a
'minefield for the unwary', but the design itself should be paste-able
into someone's project.
(unless it is some highly specific FPGA subset, that only uses half a
dozen IOs, but that's a different type of demoboard... )

A better place to drive the PCB cost down, is simply to reduce the
area.

-jg
.

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