At 06:36 PM 1/31/01 -0000, you wrote:

>
>Basically I have to use this synch pulse to contol the motor
>(keep at a constant rmp) via the chips PWM output.
>
>This sounds complicated too me, but hopefully someone out there
>will be able to make sense of it!

Use the synch pulse to determine the RPM (or the period), and
use a PID controller (in software) to control the output (say,
from 0..100%), and then feed that to your PWM module.

>If you want to know what level I am at with a PIC, then I have
>quite a bit of experience but have never done any PWM work.

The PWM is dead simple. The PID controller will require some
tuning and implementation but it is not so hard either, at least
in a case such as this one.

If you need a very close control of the RPM or some such thing
there may be other problems. You may have to alter the system
response in software by adding a digital filter or by adding some
weight to the motor shaft. Try to get only one pulse per
revolution (or divide the signal by two) to avoid jitter problems.

Good luck!


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