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Unread 16-03-2011, 11:55
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Alan Anderson Alan Anderson is offline
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Re: Robots not under driver control- does it happen- do you determine why?

Quote:
Originally Posted by willishf View Post
Optical encoders generating interrupts...
Encoders do not interrupt the cRIO. They are always handled by the FPGA. 4x encoders use dedicated quadrature circuitry, while 1x and 2x use dedicated counter circuitry.

Quote:
Originally Posted by willishf View Post
The encoders give 720 points of resolution but when I rotate our wheel 10 times by hand I get very close to 7800. I have performed this test multiple times on two different wheels and aways get 7800+/-small error. If the resolution per turn was 720 then I would expect 7200+/-small error. I can work with the 780 but just indicates something isn't working as expected.
Where did you get encoders with 720 counts per revolution? The ones in the Kit of Parts this year are 360 cpr, and 250 cpr encoders are common. Is the wheel on the same shaft the encoder is on, or is there a chain and sprocket? Has the "distance per count" for the encoder been set in software, or is it left at its default value?