Servo rotation CW/CCW vs control pulses?

Using Arduino Motors, Mechanics, Power and CNC
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Hi Everyone,
I have looked over all the Servo library stuff and some servo information and I do not find a simple explanation of "standard" servo rotation direction (CW/CCW):

  • Looking down at a typical servo output shaft
    -- Varying the Servo library write data value from 0 to 180 degrees (or just 1000 to 2000 uS)
    Does the servo rotate Clockwise?? Or Counter-clockwise??

I have 3 servos here and 2 of the 3 rotate CCW as the data to: myservo.write(value) goes from 0..180. But one, a SpringRC SM-SS4306B rotates Clockwise.

I am helping a university that has art students who use 3 to 8 servos at a time for various art installations. They will be using FEETECH FS5106B servos, mostly. There is an actual FEETECH spec sheet that says:

|旋转方向 Rotating direction|Counterclockwise (when 1000～2000 µsec)|

How consistent is this "Standard"?? I have found little information on this online.

Thanks!
Regards, Terry King
...In The Woods In Vermont
The one who dies with the most Parts LOSES! WHAT DO YOU NEED??

2

Interesting question.
In mathematics an increasing angle comes from CCW rotation.
Looking at tools, mills, drill bits,.... the standard (most commonly used) is "right hand", CW. Looking down at the work of a drill bit CW is the common one. Okey, left hand drill bits exist but they are considered as rare, special.
What a mess, total absensens of any standard.
Use the same kind of servos and state that as the standard in the project, for the university. All other turning servos are considered as "bastards"...

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There is not and never has been a "standard". All you can say is that a short pulse (may be 1000us or less) will send the servo to the end stop in one direction and a long pulse (2000us or more, 2400 is typical) will send it all the way in the other direction.

A specific type will operate the same way, usually all the models of a particular make will work the same way. But e.g. Futaba and Hitec servos have always turned in opposite directions even 40 years ago when I was first using them.

Steve

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I don't think the radio-controlled toys market has any industry-standards body working to harmonize the different brands and promote inter-working :slight_smile:

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Thanks guys... I know the school has some SpringRC servos in stock. We'll just document them VS the FEETECH.

I've used servos for many years but I didn't notice this issue until I started testing 4 or 5 types on the bench.

I have another question about servo dynamic current draw but that's really a separate subject so I'll start a thread for that, for future searches.

Thanks!

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