Subject:
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Re: calculating sensor resistance (Ohm's Law)
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Newsgroups:
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lugnet.robotics
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Date:
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Sat, 7 Apr 2001 03:03:43 GMT
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Viewed:
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538 times
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Pete Sevcik <lego-robotics@crynwr.com> wrote in message
news:3ACE6E90.3FA776D0@austin.rr.com...
> Lauren,
>
> Your diagrahm is correct. Your voltage assumption is not. On RCX the • full
> scale is 2 volts to 5 volts, not 0-5 like you have assumed. Try
> re-calculating with a 3 volt span.
That is not true for passive mode. The scale is 0v = 0 and 5v = 1023 in
passive modes like touch or temperature.
The problem with what Lauren is doing is that the Temperature conversion is
far from linear. There is a piece-wise conversion inside the RCX used to
fit the thermistor's curve. You really need to use the raw digital values.
There are ways to see the raw value using standard RCX code, but not ways to
use the values in a RCX code program. If you need some more background see:
http://www.plazaearth.com/usr/gasperi/lego.htm
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Message has 1 Reply:
Message is in Reply To:
 | | Re: calculating sensor resistance (Ohm's Law)
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| Lauren, Your diagrahm is correct. Your voltage assumption is not. On RCX the full scale is 2 volts to 5 volts, not 0-5 like you have assumed. Try re-calculating with a 3 volt span. - pete. (...) -- Pete Sevcik sevcik@flash.net Techno-stuff Robotics (...) (23 years ago, 7-Apr-01, to lugnet.robotics)
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