>complex.  Has anyone tried this?  Can you point me to any code or
>references?

Yes, several have, but they're all commercial (aveox.com, maxcim.com and
others) and I doubt they would share their code.

The simple method (no great tough stuff) is to use the encoder outputs as
the index into a lookup table, the entries in the table consisting of the
bits to write to the ports controlling the FETs.  You can still use the PWM
hardware to control the RPM with a little extra circuitry.

>Is there a way to implement a feedback control loop on these without using
>encoders?

Yes, but it requires that you either

a) Monitor the currents into the FET gates (this is being done in some
hobby-oriented controllers)

OR

b) Push the motor at a constant RPM (only good for low-load motors) by
commutating based upon a timer.

Andy

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