Subject:
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Re: (no subject)
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Newsgroups:
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lugnet.robotics
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Date:
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Tue, 29 Dec 1998 13:42:33 GMT
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Original-From:
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mwalimub@aol.!IHateSpam!com
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Viewed:
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1124 times
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No. The 10k resistor that pulls up the input line and a resister that is put
across the connection form a voltage divider. The formula given calculates
the fraction of the voltage that will be at the junction of the two resisters.
That voltage is represented by the value returned by the port. Two 10k
resistors return one half ( 10000/20000= 1/2) of whatever you're reading, so
you see 512 for raw values or 50 if it's percent.
I don't know about the other details, but I have built a prototype sensor and
it works with the values I predicted (with some allowance for varying
resistance due to defects, temperature, ect.).
chris
--
Did you check the web site first?: http://www.crynwr.com/lego-robotics
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Message has 1 Reply:
 | | Re: sensor input mux calculations
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| (...) Here is my understanding of the circuit: AVcc | Rp 10k | A/D input ---...---+---...--- | | | | | | S0 S1 S2 S3 Rc | | | | | R0 R1 R2 R3 | | | | | GND +----+----+----+---- GND Where Rp is the pullup resistor and Rc is the impedence of the (...) (26 years ago, 29-Dec-98, to lugnet.robotics)
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