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Unread 06-03-2011, 21:39
BigJ BigJ is offline
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Re: Question: how many encoders can be used on the robot?

Quote:
Originally Posted by apalrd View Post
The rate bug is in the FPGA image, so it affects all languages.
It affects every other encoder, so any number of encoders will have a few which do not return rate (the first one will be affected, the second will not).

If you only need distance, you can use the broken FPGA encoder modules for distance only, and not use Rate.
I have some questions for you experienced encoder-folk. This year 1675 has finally made its way into the world of motor feedback loops (at least on our test benchtop system).

We are using the rate on the encoder, and setting the distance per pulse to scale to -1.0 to 1.0 for the PIDController that goes to the motor controller.

I was perusing the WPILib users guide, at first because we were planning on using 5 encoders (4 drive, 1 lift) and assumed they could all be 4x (thankfully, I saw this thread!). I am under the assumption from reading the Guide that a 2x Encoder can still determine direction (our lift encoder would be a simple counter, it does need to count up and down though).

If a 2x Encoder can indeed tell direction, is the reduction in accuracy enough to make it a bad choice for drive? We'd need 4 encoders that can do rate for our current desired drive code system.