>Using an actual time value rather than a "number of counts per XX time"
>gives a MUCH improved resolutionn and lower error.  However, if anyone
>offers a method that makes use of the "number of counts per XX time" that is
>within 200 rpm, I'd probably take that.
>
        Here are two answers.

        1. count pulses for 600 ms ( 1/100 th of a minute) and the
        answer is rpm/100.  (ie  a count of 1 == 100 rpm).

        2. On the other hand if you are doing pulse by pulse control,
        for a speed control system, then maybe you could pre-calculate
        the setpoint in pulse period (us) rather than rpm. I have just
        completed a project that did just that.
Ray Gardiner ray@dsp.com.au
mail from: dsp systems

--
http://www.piclist.com#nomail Going offline? Don't AutoReply us!
email listserv@mitvma.mit.edu with SET PICList DIGEST in the body