Arduio Motor Control CLASS

I have, for the most part, finished the write-up for the motor control portion of the Arduino Project. The code works, the breadboarding is complete and the class is written. It's about time to move on to sensing input with the Arduino. However, for your enjoment, I have included a snippet from the class:

The Class

What is an H-bridge?

That’s a really good question. It is a device that allows voltage to be applied in either direction. The “H” is due to the graphical representation of the circuit used to control DC motor direction.

When controlling motors, especially drive motors, it is usually desirable to be able to not only control the motor speed with PWM, but to control the motor direction as well. To do that with a DC motor (the component used for this demonstration), one must reverse the polarity of the motor connections. Of course, this may be done with a relay, but a relay is not particularly advantageous for robotic control. One would like to be able to switch the motor direction at transistor speeds. It is possible to build a H-bridge with discreet components, but a low-cost H-bridges are available in DIP packages in such quantity that is makes more sense to try to find one of those to fit the project instead of “rolling your own”.

More information may be found on Wikipedia: http://en.wikipedia.org/wiki/H-bridge

This project uses the SN754410 Quadruple Half H-Driver. This particular unit was purchased from Sparkfun. It is a 16-pin DIP and will control two motors; 4.5 – 36 volts, one amp continuous rating. At this writing, Sparkfun offers the chip for $2.35.

The H-bridge has three distinct features that are interesting for this demonstration:

1) It can control two motors at significantly more power drain than the Arduino can

2) It is switchable at transistor speeds, direction AND speed; it supports PWM

3) It’s cheap

It also breadboards easily.

The way the H-bridge is controlled in this demonstration ...
 
And that is your tittilating tidbit for today. Enjoy!