Motomama arduino motor shield issues

Question

I loaded up the example sketch for the itead Motomama on my Arduino Mega ADK and I see the green led's in the middle of the board slowly going on and off as expected from the sketch. The problem is, as soon as I connect a motor, well, nothing happens and the LED's don't do anything either (on the side that I connect the motor . . . the other side works fine). I use the same motors on the official Arduino Motor Shield and it works fine (using a 12V input).

When I check the voltages comming off the screw terminals I see it going from about -6 volts to 6 volts . . . much like when I check the volts on any PWM pins.

I tried connecting the power directly to the Vin/Ground pins on the shield and got the same result.

And, I connected a BTBee to the XBee socket and added a bit of sample code to send text from the Arduino through BT back to my phone (using a test app) and that part works fine too.

There are a couple of jumpers on the other side of the screw terminals and I can't help but wonder what they do but haven't seen anything in the (sparse) docs about them.

Any ideas?

Answer 1

There are jumpers next to the screw terminals. I can't find anything in the docs about what they do. But on a whim (and since there were no replies here) I switched the jumpers around and IT WORKS. The test program works. I'm a bit nervous about the fact that I input 12 volts and the motor is only getting about 6 volts (see an earlier question) . . . but this chip is WAY BIGGER and even has a heatsync and I feel like it's probably the culprit. There are docs about the L298N chip in the itead website I need to check out.