I really like the look of the Baby Orangutan – it’s within my budget, and from other forum posts I’m sure some better code samples are coming soon.
My main hesitation is that two motors isn’t enough to make the sort of bots I have in mind. But at $25 each, I’d cheerfully buy two of them to drive four motors – but only if I can get them to communicate in some way.
What are my options for getting two Baby Orangutans to communicate? Or, what other options for controlling extra motors should I be considering?
The Orangutans give you direct access to the internal Atmel AVR microcontrollers, so you can program in whatever protocol you choose. You can also use one of our serial motor controllers to add more motor control.
Your protocol can be anything from a couple of lines signalling power on/off for each motor to a parallel interface that allows multiple speeds to be communicated to a serial interface similar to the one we use for our serial products. Serial interfaces are nice since they only require a few pins (or even just one pin), and the mega8 controllers have built-in hardware serial support. But, keep in mind that all of the programming for both sides is up to you.
Another option is to use just one Orangutan and add external H-bridges to control more motors. Typically, you need at least 2 I/O lines per H-bridge. The drawback is that controlling the speed gets more difficult as you add motors to a processor. The built-in H-bridges are connected to the AVR’s hardware PWM outputs, so PWM generation for those two motors does not consume processing time. For additional external H-bridges, you would have to generate the PWM in software.
Thanks, that answers my questions clearly. I haven’t used AVR chips before, but when I do, this board looks like a great way to learn.
It also looks like a fantastic board for building robots of any size – at $25 each, it’s no big deal to add more as needed. I should be able to make them honor the same Pololu protocol that your serial motor and servo controllers use, so that I could chain as many of these (Orangutans and controllers) as I like on the same serial bus. You guys have made an extremely modular, extensible system that is powerful yet has a very low entry cost.
Now, if we could just get some “Orangutans for Complete Ignoramuses” tutorials, we’d be all set!