Quote:
Originally Posted by Ether
I think you have that backwards.
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Quote:
Originally Posted by techhelpbb
At best that is a matter of 2 differring terms for the same thing.
Yes using cycle in that context seemingly eliminates the idea you can get 4 pulses from the decoder circuit, but it ignores that not all decoders are 4x decoders.
What is the difference between a cycle and a pulse in a 1x decoder? Nothing. Even over time, a bunch of pulses and a bunch of cycles, still nothing.
Granted: to the point of the OP, U.S. Digital's use of the term is what matters so I will accept the cycles per revolution in their case is 4x lower than the potential PPR as they use the terms. I prefer to think of them the other way and simply assume the quadrature encoder circuit is 1x unless provided as part of the encoder assembly.
Still a lot of good information in here on the point, minus the ambiguity of the terms.
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I like that US Digital doesn't take the decoder into account. Their encoders don't come with decoders, so why should it be their job to decide things for you? They do provide both CPR and PPR if you want to calculate your counts per revolution given your own decoder. All US Digital encoders (to my knowledge) are 4 pulses per cycle, that is, A high, B high, A low, B low, so for them it makes sense to count it that way.
Your point about the 1x decoder seeing CPR and PPR as the same is valid, but then the designer would have to determine that themselves. Are we defining pulses as the actual counts the decoder spits out, or just the step changes coming in from the encoder?
AFAIK FRC encoder decoders (TalonSRX and RoboRio) count all the step changes/pulses anyway, so for the purposes of this discussion I think using PPR = 4 x CPR is the best way to define it.
EDIT: On topic: The results of the poll are pretty interesting. It looks like most people are using 256 or 512 CPR encoders, with a few people using 64 CPR (or just picked the wrong option in the poll... I should have used CPR instead).