I'm using a air of mini gearmotors HP 50:1 with the Zumo shield.
I feed it with 6.8V from a bench power supply.
I use a 1 uF ceramic de-coupling capacitor across the terminals.
When I set the shield to go, without motors connected, I can measure appropriate voltage on the output.
When setting PWM to 192 out of 255, I get about 5.1V.
When setting pins 9/10 to high (no PWM) I get the 6.8V.
When I hook up a gear motor directly to power supply, it runs very well.
However, when I hook up the same gear motor to the motor output on the shield, it just beeps vaguely, as if it's being fed a too-weak PWM signal.
Curiously, this happens even if I just set the "PWM" pins high with no PWM.
What is going wrong here?
Secondly, it seems like one of the two gear motors doesn't run. It measures infinite resistance, and doesn't run even when power is applied. The other motor measures about 4 Ohms of resistance.
Other weird thing: The blue and red LEDs are indicated as "direction LEDs" in the documentation, but they are just all on all the time.