We have had one plane with a tiny autopilot that had significant
jitter just after power-up and the jitter dissapeared after a while or
after moving the sticks in manual. This was quite some time ago so I
should check but I think we just powered the servo's from the ESC
instead and replaced the jittering servo with a better quality one and
it was solved. Now I'm just not sure anymore which of both actions
actually solved it. I do remember checking that the pulse to the servo
was perfectly good after power-up so it was not code but some
interference/power supply servo interaction. Powering servo's other
than at most 2 micro servo's in a very small MAV from the tiny supply
is not recommended at all if you ask me.
On Wed, Jul 13, 2011 at 6:02 PM, Steffen Spies<address@hidden
I checked my files and I can clearly say, that I don't use you
airframe file, Christophe. Also the define is not part of my
My receiver is a 35MHz ACT DSL4top "MK", which I also use on my
Mikrokopter. It already sends all channels, so no PPM Encoder is
Powersupply: the jitter appears with only one Servo connected and
the supplied voltage is perfectly stable.
I took a screenshot of my scope. The signal on the top is channel
3 output of the Tiny board. The signal at the bottom comes from
The signals "stay" perfectly - no jitter.
Am 13.07.2011 08:47, schrieb Christophe De Wagter:
> Dear Dee,
> You are not by any chance using a copy of my
./conf/airframes/CDW/chimu_tinyfw_spi.xml ? This one has
ultra-fast servo updates (120Hz) with awesome performance on
digital servo's but can burn and will jitter any old analog servo?
> If you have the following define in your airframe file, remove
it or change it to 8 or 10:
> <define name="NB_CHANNELS" value="4" />
> Other possibilities include: an older PPM-ENCODER (8MHz crystal)
which has significant "digital noise" due to the interrupt routine
that needs to measure 8 channels so whenever 2 pulses are of
almost the same length one will be read with a (small) but
> A last one we saw quite often: when too many (1 or 2) small and
fast servo's are powered by the tiny/twog then it drains too much
current from the 2Amp switching supply. This also makes servo's
jitter and is very dangerous to fly with. Power the 5V of your
servo's from the BEC/ESC instead.
> If all of this is not the case, a scope would be useful to
debug. How constant are the given pulses? What is the update rate?
> On Wed, Jul 13, 2011 at 7:18 AM, Steffen Spies
> Hi Dee,
> that is a BIG surprise to me.
> Yesterday evening I made the same experience while I did
some testing: one of my servos (Multiplex Tiny S) burned out!
> And I also noticed big jitter even in manual mode sometimes
and disappears when you move the sticks - but will return.
> I use a Tiny V2.11
> Am 13.07.2011 06:54, schrieb Long Di:
> > Hello all,
> > I have started using the new paparazzi distribution
for fixed-wing. Everything works fine for my implementation except
the servo motors. Both of my servos jitter even under manual mode,
and the right servo got burned out today after a long testing.
> > The strange thing is that when I moved the joystick
handle, sometimes the jitter just disappeared, then it came back
again. I tried to seal my servo with copper tape and added a
glitch buster, didn't help. I also tried to play with the servo
parameters (min, neutral, max), didn't get solved either.
> > I also noticed the old PPM_FILTERING code doesn't
exist any more, wondering whether that should help.
> > I am using Hitec MG-82 servos. Anyone has had similar
problems? Any inputs are appreciated.
> > Dee
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