Let's Make Robots!

Help with Power HD Micro Servo HD-1900A

I just bought this micro servo from Pololu. http://www.pololu.com/catalog/product/1041

 

Is this a standard servo or a continuous one? It works like a standard servo (stop at position) from .416 ms to 2.12 ms.

From .8 us to .4152 ms, it's continuously rotating left, with increasing speed as the pulse-width decrease. Anything more than 2.12 ms does not result in clockwise rotation.

 

What's the pulse-width to make it continuously rotate clockwise?

Comment viewing options

Select your preferred way to display the comments and click "Save settings" to activate your changes.

It is a standard servo that apparently doesn't have enough of a grip on the potentiometer to stop rotating once an out of range signal is sent to it. Most servos are "standard" until you make them otherwise. The abuse the servo is taking right now, operating out of it's normal signals range, has the potential of making it unusable for standard operation.

Continuous servos should turn either direction when given normal servo pulse signals, around 1 ms for one direction, 2 ms for the other direction and 1.5 ms for stop, if they have been modified correctly. 

Oh, that explains the weird behavior. However, the rotation range is very limited. 1 ms ~ 45 deg left, thus total angle is only about 90 deg. Is there any way to expand the range?
With a standard 1 ms to 2 ms signal, most servos will only travel about 90 degrees. Most are capable of about 180 to 200 (standards anyway) and get the extra range from out of bounds signals, usually going no further than 750 us on up to 2250 us. Going further can cause problems, some servos will grind and strip gears trying to go further.