Pages: [1]   Go Down
Author Topic: Pull down resistor on servo signal line?  (Read 1051 times)
0 Members and 1 Guest are viewing this topic.
Pittsburgh
Offline Offline
Newbie
*
Karma: 0
Posts: 28
It's full of stars.
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

I have a project I'm working on that uses a lower end HiTech servo.

It's being powered by 5v from the arduino board (BBB, Modern Devices).

Once and awhile I can faintly hear the servo kind of "hiccup" (just a slight bzzzzzt lasting a fraction of a second with no perceivable movement in the servo horn). I have a feeling the signal line is picking up some interference? Would a pull-down resistor on the signal line solve this (10k?)? My gut tells me though the servo's electronic package already pulls the signal line to ground though so I'm not sure.

Any ideas? I'd like to eliminate this annoyance issue.


Logged

Manchester (England England)
Offline Offline
Brattain Member
*****
Karma: 620
Posts: 33991
Solder is electric glue
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

I doubt that a pull down would make any difference, I think you have another problem but there is not enough information supplied to hazard a guess.
If you want to post the code and a schematic theat might be something some one can spot.
Logged

Johannesburg. UTC+2
Online Online
Faraday Member
**
Karma: 91
Posts: 4257
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

I'd rather suspect the problem is insufficient power on the supply, not a problem on the control line.

Try hooking the servo 5V and ground to its own supply, not from the Arduino, making sure to connect the servo ground to the Arduino ground.
Logged

Roy from ITCrowd: Have you tried turning it off an on again?
I'm on LinkedIn: http://www.linkedin.com/in/jimbrownza

the land of sun+snow
Offline Offline
Faraday Member
**
Karma: 159
Posts: 2916
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

From my experience, I would also think it's a power supply problem, and not a signal
problem. The power leads should be short and heavy. Also, I always put bypass [100 nF]
and electrolytic caps [100-220 uF] across the servo power buss to help filter noise.

All in all, you should probably try different things to get more info. Eg, start with tacking
a pulldown on the signal wire, and see if that helps, on and on.
Logged

0
Offline Offline
Tesla Member
***
Karma: 141
Posts: 9560
Arduino rocks
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Typical servo external power supply setup. I've seen servos occasionally twitch when being controlled by an arduino, but don't remember the cause or fix.

Logged

Consider the daffodil. And while you're doing that, I'll be over here, looking through your stuff.   smiley-cool

Manchester, New Hampshire
Offline Offline
Edison Member
*
Karma: 4
Posts: 1363
Propmaker
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Are you doing anything else in the code besides updating the servos?  Specifically anything which uses interrupts or disables them?  I've found that when the timing of the pulses that goes to the servos isn't perfect the servo will do that since it thinks it's slightly off from there it should be.
Logged

Pages: [1]   Go Up
Jump to: