[Mr. Lim]

I also highly recommend Kevin's code.

We used it on our FRC last year and it worked PERFECTLY. We also used it with a relatively low-resolution encoder, about 64 ticks per revolution.

Some advantages:
- Uses interrupts, so that you don't have to worry about missing your encoder ticks.
- Reads two quadrature outputs, so that you can detect which direction your encoder is spinning (increment your encoder variable when spun in one direction, decrement it in the other)

Things to look out for:
- The version I used had one interrupt per encoder, and interrupted only on rising edges
- This meant my encoder variable would only increase or decrease after about 4 encoder state changes, dividing my effective encoder resolution by 4
- This wasn't a BAD thing, in fact it was a very good exercise in learning, and implementing two interrupts per encoder, which interrupted on rising AND falling edges, and gave me back full encoder resolution

*hint: don't use two interrupts per encoder... to me external interrupts are more expensive than getting a higher resolution encoder. Last year, we had an interrupt or two to spare after we removed our IR after Pittsburgh. Next year, I know we WON'T have any spare external interrupts. I know it sounds crazy, maybe this advice comes a bit late, but buy an encoder with twice the resolution you expect to require.

It gave me a great opportunity to teach students about interrupts vs. polling, and the concepts of rising edges, falling edges and such. Even the whole concept of quadrature was quite interesting to them. Most didn't think it was that easy to figure out which way an encoder was spinning. In addition, we purchased an inexpensive mechanical encoder where we opened up the back, and you could physically see how the quadrature signal was generated with just a sweeping arm, and a few contacts.

I definitely learned a lot, and so did the students on 188.

Thanks Kevin for your code! We used your IR code too =), and were very successful in our empty gymnasium, but weren't so successful on the actual playing field.

-Shawn...