Thread: 775pro encoders
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Unread 21-01-2016, 23:01
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Re: 775pro encoders

Quote:
Originally Posted by Munchskull View Post
My one of my mentors wants to know if they can handle 19000rpm
Well, it was designed specifically for the 775Pro whose free speed is 18730 so I would hope the sensor can mechanically and electrically handle that speed. Andrew, can you post an oscope trace at full speed?

As for the FPGA, the new higher FPGA sampling speed should handle it, even with the quadrature errors shown on the oscope trace posted earlier in this thread:

Code:
19000	rpm
316.7	revs/sec
3	cycles per rev (assuming 6-pole magnet w Hall sensor)
4	edges per cycle (quadrature)
12	edges per rev (quadrature)
3800	edges/sec (quadrature)
40.7	quadrature error (degrees)
182.6%	quadrature error (percent)
6937	edges/sec (with quadrature error)
If you are going to use this for speed control of a shooter wheel, follow the advice Richard gave in his earlier post and use rising edges only in one channel only, to give the cleanest (jitter-free) speed signal (especially if using bang-bang control).


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Last edited by Ether : 21-01-2016 at 23:27.
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