Arduino mega Pin3 (PWM) Not for Servo ?

Using Arduino Motors, Mechanics, Power and CNC
1

hi all,

i found a fact what seems mysterious to me

had built an Relais - Array with servos, what presses/releases microswitches
to switch model railway circuits. that works wonderful except one servo
got warm and buzzed continously even without any order to do anything..

4 pwm pins of A.mega where used (3,4,5,6) , the one "buzzer" used pin3

watching the pin-diagram for A.mega i realized that pin 3 was marked as PWM/Int ,
the others only with PWM.

does Int causes the servo to act mysterious ?

then i connected same servo to pin7 (pwm) and all worked fine !

who can explain me what the int (interrupt ?) means on an pwm-pin ?

2

Please post your sketch, using code tags when you do

Use of the Servo library does not require a PWM capable pin to be used for the servo

3

Hi, @lupus51

Any reason you haven't used relays, as microswitches are just ON/OFF devices?
Does the servo get warm and buzz if connected on its own?

Tom.... :smiley: :+1: :coffee: :australia:

5

A number of pins can have more than one functionality. Based on your description, pin 3 can be an interrupt pin (input) or a pwm output or a general purpose IO pins.

6

hi..what do you mean with this ?

by the way, i have tried that with bistable relays - that was discussed in older thread -, but they switched ocasionally without order too..that was not a solution..

my goal was to strongly separate controlling and powering circuits and use this with model railway with and without protocol..

as i have no oscilloscope i cant see whats going on at pin3

7

If you have just the troublesome servo connected, the others disconnected, does its fault happen?

Can you please post a link?

Tom... :smiley: :+1: :coffee: :australia:

8

hi tom..im sorry, maybe that was discussed in a different forum

forum-modellbahn.com/search.php?maxage=&minage=&q=bistabil+relais&type=all&matchtype=or&im_feld=text&orderdirection=DESC&orderby=date

what is in german language completely

the fault happend isolated too !

9

And why couldn't you get such a simple concept to work?

Bistable relays, why? Did you try the usual type?

Tom... :smiley: :+1: :coffee: :australia:

10

Have you got some code that JUST operates that servo, no other code, no other servos connected.
Just a simple bit of code?

A copy of your existing code would help too.

Thanks.. Tom.. :smiley: :+1: :coffee: :australia:

11

It's a very strange idea to use a servo/microswitch combination instead of a simple relais ( not bistable). Why didn't you try with simple relais? I use lots of relais on my model railway without any problem. I use servos to set turnouts only :wink:

12

hi,

as i was adjusting the servo-arms for postions to press the microswitches correctly,
i was not aware that problem and didnt realize it, because the on-job-times were
rather short.
The code for adjusting a servo is like example inVarSpeed-lib, only pin modified..
the speed is at 150.