Actuator
Using PWM fan speed control makes the software to control the fan simple, requiring only that we connect one pin on the Javelin Stamp to the gate on the power transistor, and then drive that pin with a PWM virtual peripheral in the code.
The PWM object runs in the background, delivering a constant pulse train to the fan at the duty cycle specified to the update routine.
There’s a minimum pulse train duty cycle that will actually rotate the fan; the fan we used didn’t rotate for PWM values below 30 or 35. For that reason, we incorporated this logic into the main loop of the controller to keep the motor either shut off or rotating slowly.