Subject:
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Re: Reading encoder forward/reverse
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Newsgroups:
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lugnet.robotics.handyboard
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Date:
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Wed, 22 Nov 2000 13:15:48 GMT
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Viewed:
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890 times
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In lugnet.robotics.handyboard, Richard Giuly writes:
> I would like to tell which way my optical incremental encoder is turning. It
> has two outputs, one offsett from the other. Is there any library around that
> can count and give direction? (the "encoders.c" functions seem to only count
> regardless of direction) If no premade software handles this, would it be
> difficult to write it?
>
> thanks
> rgiuly@bigfoot.com
Hello Richard
I think you should use a Gray code (consecutive decimal numbers are
represented by binary expressions that differ in the state of one, and only
one, one bit. Synonym: reflected or mirrored code). Its very simple for two
bits:
00
01 10
11
This code only changes one bit position between two adjacent code-words. So
no problem whith glitches, and... ¡It has direction info!
Theoretical complexity of higher order Gray-binary conversion is O(N-1),
where N is the word length. But there are algorithms with lower complexity.
Next is for a DSP, use it as "pseudocode" and translate:
unsigned short binaryToGray(unsigned short num)
{
return (num>>1) ^ num;
}
unsigned short grayToBinary(unsigned short num)
{
unsigned short temp = num ^ (num>>8);
temp ^= (temp>>4);
temp ^= (temp>>2);
temp ^= (temp>>1);
return temp;
}
Hope it works with you.
Juan José Escobar Mira
www.fractals.8m.com
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Message is in Reply To:
 | | Reading encoder forward/reverse
|
| I would like to tell which way my optical incremental encoder is turning. It has two outputs, one offsett from the other. Is there any library around that can count and give direction? (the "encoders.c" functions seem to only count regardless of (...) (24 years ago, 21-Nov-00, to lugnet.robotics.handyboard)
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