Cheaper Alternative to Tallon

[bharrison6]

Is there any pwm or CAN operated motor controllers that are cheaper to buy than what is normally used for FRC. Reason I am asking.

I am a teacher implementing a Robotics class. I have almost 0 funds. My team is a team ran by two high schools with again almost 0 funds. We only have two roborio's so this is the plan for our class.

Raspberry Pi2 Model B has some pretty impressive features. I am looking into how I might produce pwm signals from them to run motor controllers or possibly a CAN signal. They cost ~$35 each.

For motor controllers I found.
http://www.ebay.com/itm/like/201336780734?lpid=82&chn=ps
These use PWM but I don't believe they will work like a talon because they are speed "forward" only. There are some that have a reverse switch which could possibly be programmed to automatically switch when you need to reverse but I think half the PWM being used for forward and half for reverse like FRC motor controllers would be easier. Any alternatives in that $15 range?

[Scott Kozutsky]

I was looking into similar stuff recently and this is the best (read: cheapest) I could find:

http://www.banggood.com/HSP-HPI-320A-Brushed-Speed-Controller-ESC-p-86639.html

This is a speed controller intended for an RC car. With the recent rise in brushless motors it's gotten harder to find brushed speed controllers (all FRC legal motors so far have been brushed). I would not run CIMs with this speed controller as I really doubt it could handle the stall current but it may be worthwhile to experiment (they're less than $15 so not too much is lost). They should be fine for bag motors or banebots though. I have not actually purchased or used these so take this recommendation with a grain of salt.

Also keep in mind that this isn't actually rated for 12v. It should be able to handle it but this may require more testing.

Look for more ESCs for RC vehicles-they're all PWM and you should be able to find relatively cheap stuff.

edit:
cheaper ones:
http://www.hobbyking.com/hobbycity/store/RC_PRODUCT_SEARCH.asp?strSearch=turnigy+Brushed+ES C

[GeeTwo]

There are several arduino motor shields that are suitable for 25mm motors. You can get a controller shield that will manage four motors for less than one Talon. Not exactly CAN or PWM, but libraries already in place to program them. If you really want PWM, you can probably program the arduino plus the shield as a 4-motor PWM controller.

[efoote868]

Is there any pwm or CAN operated motor controllers that are cheaper to buy than what is normally used for FRC.

What size motor are you looking to drive?

For my senior design project two years ago we used a pair of L298N Full H-Bridges to control a couple of vex 269 motors. The control wasn't fancy, just a duty cycle at about 20kHz to keep it above the audible range.

Sparkfun has these and breakout boards for pretty cheap -
https://www.sparkfun.com/products/9479
https://www.sparkfun.com/products/9540

The nice part about VEX was the integrated encoders, the less mechanical design us EEs and CompEs had to do the better.