Re: Spinner Replacement for Omega Race

From: Ed Henciak <>
Date: Fri Aug 01 2008 - 03:15:26 EDT

> 3) functions, so based on my experience you might want to stick a
> 74HC14 on the inputs to the
> 5) What's the crystal for?
My guess is that 3 & 5 are related :-)!

Basically, you can deglitch by simply filtering out the previous 3 or 4
samples. If your past four samples are all '1's, you know you have a
valid '1'....same with zeroes. Then, you stay in your one or zero state
until you sense a deglitched 1 or 0. I made a Xilinx PLB peripheral
with this and lots of other features for some robotics applications.
The function is very lite in terms of logic utilization.

> 4) A little MCU might be more flexible than the CPLD if you wanted to
> support more input/output formats. With a ~12MHz AVR I can read four
> channels of quadrature encoders and still have time to do light gun
> sensing and other tasks and still get 1000's of times oversampling.
> Can't outrun it with the shaft connected to a power drill. ;-) You
> don't need pullup resistors either since the AVR has 'em built in and
> even the smallest AVR could have multiple programs built in for
> different input/output formats. Also allows you to get around input
> noise issues in software too, so you save the 'HC14(s)...
Oh you and your AVRs :-P !!! What fun is that :-P (just kidding). A
microcontroller is going to give you a lot more flexibility....but the
function seems so simple that a PLD would be so much straightforward in
this case....I guess its designer preference :-)! Just curious Bill,
what is your resource utilization in the PLD? I see you're using a 72
macrocell device....I kind of think a 36 macrocell device would work
here just to save you a few cents.

This is a dumb idea, but you can implement a simple sigma-delta DAC in a
PLD/FPGA....I wonder how difficult it might be to make an optical
solution for Star Wars / Spy Hunter controllers...I hate those pots.
Aren't they up to $15 a piece for those industrial ones? I understand
that once you install them for home use, you'll never need them again,
but I am sure those are going to be harder to source someday soon.


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Received on Fri Aug 1 03:16:11 2008

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