Subject:
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Re: What about multiplexing sensors?
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Newsgroups:
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lugnet.robotics
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Date:
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Wed, 11 Nov 1998 20:57:33 GMT
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Original-From:
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Larry Coffin <lcoffin@pointSAYNOTOSPAMinfinity.com>
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Viewed:
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2822 times
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> Hang on - if you use all 3 outputs to control the MUX (which leaves me
> wondering why you'd bother - trees falling in forests and all that) you
> can get 24 inputs, even if you only treat each output as binary.
Sure, if you want to give up all three output ports -- which most
people don't want to do. A no output RCX seems to have a pretty limited set
of applications to me. At least with two output ports you can drive and
steer a robot.
I was using the single output port as a ternary state output --
off, on forward, and on backwards. Which gave me 9 sensors. Using all three
output ports you could get up to 81 input sensors. Or 27 using two output
ports.
If you could decode the eight power levels the RCX can produce, you
could theoretically use each output port as a 17-ary state output -- 14,739
sensors using all three output ports! But decoding the power levels has
proven to be a bit difficult.
Or rather than using each output port as an n-ary state output you
could use it as a 'clock' (i.e. turning the output port on and off) to
increment an n-bit counter to cycle on every pulse through however many
sensors you want.
This can possibly be applied in such a way as to free up all the
output ports by using one of the input ports to produce the clocking signal
-- switching between a touch sensor and a light sensor can be used to
produce two different voltage levels.
If we can get at the hardware directly from software once the
firmware/ROM has been decoded, it might be possible to do a lot more using
just the input ports. (That is if we can control the voltage through the
input ports ourselves.)
---Larry
+-----------------------------------------------------------------------+
Larry Coffin lcoffin@PointInfinity.com
Point Infinity http://www.PointInfinity.com
Nantucket, Massachusetts 508-325-6677 * fax: 325-6676
+-----------------------------------------------------------------------+
Cold, adj.:
When the local flashers are handing out written descriptions.
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