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How to stop a continuous rotation servo?

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johnwarfin:
actually has little to do with the mcu and 1.5ms rarely works to stop a servo. removing pulses entirely is the best method. most srvos will stop dead.

Duane Degn:

--- Quote from: johnwarfin on April 28, 2013, 10:37:06 PM ---actually has little to do with the mcu and 1.5ms rarely works to stop a servo. removing pulses entirely is the best method. most srvos will stop dead.

--- End quote ---

It has a lot to do with the microcontroller. Some uCs pulse the servos in the background and you have take action to turn the pulsing off.

1.5ms will always stop a CR servo that has been properly adjusted with a trim pot. Many servos jitter pretty bad when they don't receive a pulse on schedule but I haven't tested completely stopping the pulses.

johnwarfin:
as a developer of radio control products ive collected over 40 different models of rc servos (towerpro, turnigy, gws, etc) and about half of them converted to continuous rotation. in no case did i experience jitter when removing pulses. however jitter is 100% a problem with 1.5ms pulse. and with the slightest change in temperature or voltage like battery dropping it almost always starts turning one way or the other. slowly at first then picks up speed with time. was never able to adjust this out with trimmer and fixed divider even worse.

this is just my experience. i suppose its possible there are exceptions but  hard to believe with the limited number of servo ics out there.

Duane Degn:
Well that's something I didn't know. I've just seen so many programs with misbehaving servos caused by not supplying the servos with a 50Hz pulses. It just seems wrong to me not to send any pulses. It sounds like you've done this with a greater variety of servos than I have so I'll take your word for it.

It still just seems wrong to starve the poor servo of its refresh pulses but if it will turns off the servo, it's a lot easier than trying to add a relay.

jwatte:
Hobby servos are designed to stop applying torque if they lose the controlling pulse. This is a safety feature for when a transmitter is turned off or goes out of range, for example. All servos I've used have behaved like this. You may also have experienced this: If you power on a servo before you provide a pulse to it, it will not apply any power!

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