2015 Control System Alpha Testing

[AustinSchuh]

I'm curious how the rRio deals with a second high bandwidth USB device being used at the same time as the usb radio. Are both ports connected to the same root hub so that they share the bandwidth? Having written a USB driver for work, I have learned enough to be skeptical of USB.

I'm also curious what the bandwidth is to the various digital inputs and outputs. How fast can you actually read them by polling? I have seen other controllers (Chumby Botball Controller, I'm looking at you) get this very wrong. Hook up an encoder, and count the edges in polling code. See how fast you can spin it before loosing counts.

What rate can the controller actually read encoders? Edges/second. How many encoders can it support?

We used (before it lost us a regional) a feature in WPILib which let us read an encoder immediately after a hall effect had a positive edge by firing an interrupt. This was awesome since we could use it to figure out when a joint passed the homing position without having a polling delay. Does this work in the new version?

How is the timing jitter? +- ?% Am I going to have to work really hard to get my timing accurate to avoid control loop problems like on the cRIO? I can't count how many control loop problems ended up being timing jitter problems...