Arduino H-Bridge Help

Forum 2005-2010 (read only) Hardware Interfacing
1

I have a Arduino Duemilanove, the robot that I am building has 4 DC Motors (13.1v 1.1amp).
Two of the motors will spin the same way and speed (so one h-bridge).
I need the motors to spin both directions. So i need three h-bridges?

I found this tutorial showing a basic circuit for one motor and an h-bridge.
https://sites.google.com/a/divinechildhighschool.org/electronics/Home/Arduino-Lessons/h-bridge

It leads me to think that i will need three wires per h-bridge. Is this correct? If it is then i am left with only two digital pins after the motors (i knew i should have bought the mega ;)).
The two motors that are alone on a h-bridge need to be able to spin different directions at the same time and different speeds (with a pwm pin).

So my main questions:
Do the h-bridges require three wires (for controlling)?
Or is there a more efficient way of wiring them up?

2

Two of the motors will spin the same way and speed (so one h-bridge).

The link is a little confused; it says:

An h-bridge motor controller is used for two very useful purposes: one is to control two motors at the same time

That's not generally true: an H-bridge will control normally one motor, but the 293D has two H-bridges in the same package.

3

I see.
Regardless of the controlled motors, would it still need three wires from the Ardunio for control?

Thanks

4

It depends on how much control you need over the motor - whether or not you can have free-wheeling, or you need braking, and whether or not you can have external logic take care of some of the signalling.

Two wires per motor (speed and direction) would be the bare minimum, normally, but again with some external logic, you could probably share a direction signal (at the expense of one or more other signal pins) round several motors, because you don't have to change that very often.

5

Thanks
I found this tutorial that explained everything to me. I wish I paid more attention in my hardware classes :wink:
After looking at the datasheet for the SN754410 and L293D i realized they may not be the best choice for my motors due to amps.
So i will be making the one this guy is talking about.

http://www.mcmanis.com/chuck/robotics/tutorial/h-bridge/bjt-bridge.html