pic: FRC973 Presents Emperor Swerve

[Joe Ross]

Originally Posted by AdamHeard

If you try to read more than 4 encoders at 4x resolution, the remaining encoders will always repeat a zero value. After hours of debugging, seeing the encoders actually generate pulses, but not increment, we were going crazy.

This is documented in the WPI Robotics Library User’s Guide. It looks like Java and LabVIEW give errors if more then four 4x encoders are allocated, but not C++.

Originally Posted by Tom Bottiglieri

Ugh, don't get me started on encoders and the cRIO. We used a ton of encoders and it seems every combination you can think of using 4x, 2x, and 1x decoding would break something or other. I guess that's what happens when everything on the FPGA is a black box.

Did you have problems with anything other then the rate output? That was the only reported problem. That's been fixed in off-season updates for C++ and LabVIEW.

Originally Posted by Gdeaver

The C-rio only has 4 4x encoders. Why not save them for velocity needs?

I recommend the opposite if you're using the FPGA's rate. With 4x encoding, you get more noise in the velocity due to quadrature phase errors in the encoder wheel. I recommend 1x for velocity and 4x for distance.