>walker, using 3 PIC16C84's (2 legs=4 RCservos to a PIC) and a 68HC11
>...
>(pity the '84 doesn't have the input/output capture facilities of the 68hc11)

I suggest using a PIC16C72 with a 74259 to send the output.  This will
extend your output abilities quite a bit, plus you get 1uS resolution with
4 MHz osc.

>In time I'll hack into the servos to get at the 'error' voltage so that
>I can integrate some kind of force feedback into the system (may have to
>add another PIC to handle this.. but that's the beauty of subsumption I
>guess; just plug in another processor!)

You could then use the A/D channels to read the position of each servo, all
in a single processor.

This is pin-compatible with a '73 to gain more code space and serial-comm
(SPI master/slave or I2C slave or standard rs-232/485).

Andy

==================================================================
Andy Kunz - Montana Design - 409 S 6th St - Phillipsburg, NJ 08865
          Hardware & Software for Industry & R/C Hobbies
        "Go fast, turn right, and keep the wet side down!"
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