Hi Alec,

Are you sure that all the servos have been accessed within a 20 ms window.
I don't know how many servos you have connected or what type of program
is running in your PIC.

     -----                   -----
    |     |                 |     |
----|     |-----------------|     |------

---> 1-2ms <----

     <------ <20ms  ------->

This might help

Eric Naus

At 05:09 PM 10/25/97 +0100, you wrote:
>I'm having a bit of difficulty with some cheap RC servo units (being driven
>from a PIC).
>
>Every now and then, the servo unit goes into a funny oscillating mode
>(frequency the same as the driving pulses). It draws lots of current
>(>500mA), and the stiffness of the unit drops off to about zero. If I
>change the length of the pulses, the servo moves off to the right place,
>and (usually) stops oscillating. I've tried adjusting the amount of
>friction in the system, but that doesn't help. I don't think it's a
>'hunting' problem, because you can move the servo a long way off it's
>correct position without any effect.
>
>The driving pulses are quite stable in length - it's not a problem at the
>PIC end, I don't think.
>
>PIC and servo run from different power supplies, Control pulses are between
>~1mSec and ~2mSec applied at about 50Hz.
>
>If anyone's got a clue what's happening, I'd be grateful for their
suggestions.
>
>
>Alec
>
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