Hi all,
I bought a MotoMama shield the other day and tested it tonight. As you may know it uses a 298.
I didn't bother with a sketch in the Uno, just used the Uno as a 5v power supply to the logic side of the MM board, and breadboarded some other 5v and ground lines to hard wire the motor enable and direction.
Then I hooked up a "toy" 3v motor and a 2x AA power pack and expected to see the motor spin. Nothing.
Dismantled, put 3v on the motor, and it ran.
So then read the MM datasheet more carefully, it says the motor input must be 3.3v minimum; measured my 2x AAs at 3.2.
Then I dug out my 6v Magician motors and their battery pack (measured at 6.2 iirc), put one in in place of the 3v motor and 3.2v supply and it ran as advertised.
Moral of the story... when the MM datasheet says 3.3v minimum, they really mean that. (Interesting that, since the motors themselves ran fine with the 3.2.... obviously something in the MM or 298 that prevents output under 3.3.)
Anyway, now I know that both channels of the MM board are good and both Magician motors run in both directions....