Low Res Optical Encoders for Speed Control

[KrazyCarl92]

This summer, Team 20 is revisiting a problem we experienced during the competition season. We had our shooter wheels powered by Banebots RS550s and on speed control with a 360 count encoder on each shaft connected to CAN jags. However, when our jaguars kept having brown-outs in CAN, we switched to PWM control, which meant we could not use the 360 count encoders for speed control at such high rpms (bye-bye shooting accuracy).

So now we are trying to resolve the CAN issues, but in the event that we cannot, we would like to have a back-up plan to get closed loop control with PWM. This would require a different sensor then we are currently using to measure rotation (we are currently using 360 count US Digital E4Ps).

Has anyone had experience with low-resolution optical encoders? And by low resolution I don't mean 64 or 100 counts per revolution, but more like single digits. I found this while searching on Digi-key:

http://www.digikey.com/product-detai...008S-ND/954400

, but I'm accustomed to using 4 pin connections with encoders (power, ground, A channel, B channel), and the ones I am finding all have 6 pins. The additional 2 pins have something to do with a switch according to the datasheets, but I have no clue how to work with that. Has anyone worked with something similar before or does anyone have other suggestions? The reason I'm interested in low-res optical encoders is because we know how to work with them, but I have seen teams with other solutions, so if there are other simple and effective ways to do the task we'd love to hear about those too.