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Unread 07-01-2015, 16:32
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Re: CAN mode question

Quote:
Originally Posted by ozrien View Post
If you really want the details checkout the Talon user's guide and Talon software ref manual at....
http://www.crosstheroadelectronics.c...ol_system.html
Also the FRC screensteps page has lots of good info...
http://wpilib.screenstepslive.com/s/...ribution-panel
I skimmed the software manual, and I would like to buy a Mountain Dew or beverage of choice for the people behind the firmware. The Talon firmware solves SO many problems with using advanced features on the Jag:
  • Unsolicited position and velocity feedback. You had to poll the Jag and you could only get feedback for the closed loop mode you were in.
  • PIDF with automatic and triggerable integral anti-windup. The PID on the Jag was nigh useless without feedforward and anti-windup.
  • On the fly gain schedule switching and single frame parameter setting. Setting P, then D, then I while closed loop is live would be pretty terrifying.
  • Slave mode. You couldn't use the onboard PID on the Jag anyways if you were planning on driving a system with more than one motor. Now if your lift is underpowered, slap a second motor on and slave the Talon to your primary.
  • Single edge count up feedback. Cause it makes flywheel shooters easier and you can't on a Jag.
  • No more BDC Comm.
  • No more BDC Comm.
Thanks not even mentioning the vastly improved electrical specs and positively miniscule size and weight.

However, I do have a few suggestions/feature requests for future firmware releases. Some are admittedly based on my assumptions about how you're doing things, since the firmware source code isn't available and we don't have our Talons or a system to test them on yet. So far it's three things that aren't mentioned in your firmware feature list in the SRM:
  1. Velocity averaging. I'm assuming right now you're just counting pulses per PID cycle, which can make for pretty coarse feedback in some cases. 2^n rolling average should be pretty simple to implement, and would stabilize values.
  2. Analog filtering. Either same 2^n rolling average, or a simple exponential filter to deal with a noisy signal.
  3. 1/period velocity feedback. It's a lot more accurate at low speeds/counts, and sometimes even better for flywheel feedback.
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