Hi,

Well, I'll assume you wanna control a DC motor:

    To control a speed of a DC motor, usually we send a
pulse-width-modulated-signal.
    You must care about two little problems when you do this:
    1st) A DC motor is an inductance, and you must protect the rest of
the circuit - remember that you are sending pulses!
    2nd) You CANNOT control the speed of your motor directly, only the
force that his axis make on the load. When the load is a constant, the
speed will be proportional to the input current. If your load is
variable, you are in big trouble... :)   (In this case, get the output,
compare to the input and increase/decrease the PWM signal)

    If you can choose, use stepper or servo motors, ther control is
easier.

    Take a look at: http://olympus.math.niu.edu/~behr/RC/pwm.html


            see you!

                        Roberto Neto

Aaron wrote:

> Can anyone help I am wanting to control a motor from my pic 16c84.  I
> want to be able to vary the speed of the motor. regard Aaron Bott

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