Sean,

Actually, I should have read better original post as he indicated the signal
available on the receiver, which yes means after decoded of course. I agree
the signal on the servo is PWM, but the FM transmitted is PPM coded - but
this signal is not the one you care about when you use the one already
decoded by the receiver.


2007/5/7, Sean Breheny <shb7@cornell.edu>:
>
> Hi Ariel,
>
> It IS actually PWM, just PWM where the maximum "on" time is not 100%
> of the period. The frequency is usually around 50Hz, and the "on" time
> varies between 1 and 2 milliseconds (which would be 5 and 10% duty
> cycle).
>
> The signal received by the receiver is PPM encoded, but the receiver
> converts this into PWM for each servo. Note that unlike regular PWM,
> this is not used to directly drive a motor but rather to send a
> command.
>
> Sean
>
>
> On 5/6/07, Ariel Rocholl <arocholl@gmail.com> wrote:
> > Minor correction: PPM for RC is pulse "position" (as opposed to width in
> > PWM) modulation.
> >
> > 2007/5/6, John Ferrell <johnferrell@earthlink.net>:
> > >
> > > The radio output of an RC receiver is a pulse. The width of that pulse
> > > determines the servo position. The accuracy and repeatability as well
> as
> > > the
> > > output power are reflected in the price of the servo. You can either
> work
> > > from that pulse OR use a high quality servo of your choice to turn a
> knob.
> > > Most of that kind of setups balance a bridge.
> > > The chips in the servos have all been unobtainable by me!
> > > Good luck...
> > >
> > > John Ferrell    W8CCW
> > > "Life is easier if you learn to plow
> > >       around the stumps"
> > > http://DixieNC.US
> > >
> > > ----- Original Message -----
> > > From: "Bob J." <rocketbob@gmail.com>
> > > To: "Microcontroller discussion list - Public." <piclist@mit.edu>
> > > Sent: Friday, May 04, 2007 9:17 PM
> > > Subject: [PIC] r/c receiver interfacing
> > >
> > >
> > > >I am looking to build what is essentially an a huge radio-controlled
> > > servo
> > > > with a stepper motor.  In order to drive the stepper motor, I have
> to
> > > > convert the r/c receiver's pulses into step/direction pulses.  To my
> > > great
> > > > surprise I googled for something off-the-shelf to do this, but have
> come
> > > > up
> > > > empty-handed.  Has anyone done this sort of thing?
> > > >
> > > > Regards,
> > > > Bob
> > > > --
> > > > http://www.piclist.com PIC/SX FAQ & list archive
> > > > View/change your membership options at
> > > > http://mailman.mit.edu/mailman/listinfo/piclist
> > > >
> > >
> > >
> > > --
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> > >
> >
> >
> >
> > --
> > Ariel Rocholl
> > Madrid, Spain
> > --
> > http://www.piclist.com PIC/SX FAQ & list archive
> > View/change your membership options at
> > http://mailman.mit.edu/mailman/listinfo/piclist
> >
> --
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>



-- 
Ariel Rocholl
Madrid, Spain
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