I'm using a motor shield to control a normal rotary motor, which runs off a 12V battery. The motor shield appears to provide the motor with full power, the same as an analog switch setup. However, when the motor is presented with any physical resistance, some sort of safety feature appears to kick in via the shield and shut off power to it, regardless of what pwm I write to it, whereas running on a simple analog switch it can produce enough torque to overcome significant physical resistance to its rotation. As it is involved with a robotic arm, this lack of torque is a massive problem for me. Thoughts?
What is the maximum current the motor driver shield can sustain, and what is the stall current of the motor at the voltage you're using?