Hi,

I have built a simply PWM DC motor circuit that I have in a book about lasers. I use it to spin mirrors at different speeds inorder to produce a laser light show. The circuit has just a 555 timer, couple passive components, a transistor to handle the current, and a variable resistor to vary the PWM. The motor I use is a little hobby motor like out of a remote control car. What I would for your problem is use a similar circuit. The cpu will be the 555 timer circuit. Just add the transistor circuit to handle the power. Then "play" with the PWM command to get your speed range. This can be measure using a make-break IR led/IR detector circuit and a wheel with a hole on it attatched to the motor. Maybe hooking the detection to an interrupt pin? Don't know how that would affect the PWM command usage though. Well, written a book. Gotta go. Please let me know if you need the circuit. I can email it to you.

TTYL,
Dave