How to control a acoms servo as-12 using a uC
Rasmus Nielsen
I was wondering if anybody knows how to control a acoms servo as-12
with a microcontroller Atmel (8051). I cant get it to work using puls
width modulation as described here
http://www.robologic.co.uk/tutintser.htm
Could it be that it uses a different timing ?? It has 3 wires, black,
red and yellow.
Hope someone can help
Best Regards Rasmus Nielsen
Randy M. Dumse
news:5a20ca79.0212...@posting.google.com...
> I cant get it to work using puls
> width modulation as described here
> http://www.robologic.co.uk/tutintser.htm
> Could it be that it uses a different timing ?? It has 3 wires, black,
> red and yellow.
First question, do you have any standard servos you can try with? If so,
you could verify your RC servo signal with a known standard. I don't
know the servo you are trying to use, but I know that tutorial's diagram
can be very misleading. It says it is not to scale, but it would lead
you to believe the 2ms pulse repeats almost immediately. If you are
updating 50 times a second, that means the total time for a pulse is
20ms. That means your 2ms "on" pulse will be followed 18ms "off" pulse.
(The signal is high only 10% of the time even at the maximum setting,
and 5% at the minimum.) If you crowd the update rate of the servo too
fast, it just won't work.
--
Randy M. Dumse
www.newmicros.com
Caution: Objects in mirror are more confused than they appear.
Gordon McComb
like the others. The overview at Robologic should work. Assuming your
code is correct, then the usual suspects apply:
1. Use a separate power supply for the servos. When turing servos can
draw considerably power. If on a smallish 5v regulated supply, the
voltage can well sink below the brownout level and cause the controller
to reset. Servos do not need tight voltage regulation, so run 'em from
their own 4.8 to 6 V batter pack.
2. If already using a separate power supply, be sure the grounds of the
supplies for the controller and the servo(s) are connected.
3. The color coding on servos is nearly universalm with black or brown
for ground, red or orange for V+, and the remaining color (e.g white,
yellow, etc.) for signal. Be sure this conforms to your wiring.
4. Though rare, sometimes output pins of controllers can't directly
drive the inputs of servos. Route the signal through a buffer chip. If
using an inverting buffer, be sure to re-invert the signal so it's the
correct polarity.
5. Cross your fingers before pressing that reset button. You did do
that, right??? <g>
-- Gordon
Budget Robotics -- http://www.budgetrobotics.com/
<Mark> <McGahee>
which are not standard) see the following link:
http://www.fatlion.com/sailplanes/servos.html
--
Regards,
Mark McGahee
m a r k m c -a_t- s o n i c -d_o_t- n e t
"Rasmus Nielsen" <E01ra...@student.hih.dk> wrote in message
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