Parallax Standard Servo

Technics

Hi,
I am having some difficulty wrapping my mind around the idea of servo control. I got a servo with the discovery kit. So I want to control to motor so it rotates continously (360 degrees). I am new to this stuff, so can someone explain to me how to make the motor rotate continuously. Also I want to know how reverse direction.
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Thank you All
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Andy Lindsay (Parallax)

Standard servos are good for controlling the position of something like a boat rudder or an airplane flap. The signal that tells a standard servo where to turn to is a pulse that is delivered every 20 ms. The pulse can range from 0.5 ms to 2.5 ms, and that instructs the servo to turn and hold the horn somewhere between 3 o-clock and 9 o-clock. For example, if you deliver a 1.5 ms pulse every 20 ms (that's in the middle of the pulse duration range), the servo will hold a position in the middle of its rotational range, around 12 o-clock. BTW, that would be PULSOUT 14, 750 because the PULSOUT command times its pulses in terms of 2 us units (2 millionths of a second x 750 = 1.5 thousandth of a second, or 1.5 ms.) So long as the pulses are delivered once every 20 ms, they servo will hold that position. If you try to push the horn out of the position it is holding, it will push back.· When the pulses stop, the servo becomes inert, and you can then rotate the horn and it won't resist.

The easiest way to change from holding a position in a 180 degree range to rotating backwards and forwards in a 360 degree range is to get the Parallax Continuous Rotation Servo. They're only $6.95, and they take the same kind of signals a standard servo takes.

For all kinds of continuous rotation servo control examples, you can download the PDF version of the Robotics with the Boe-Bot text from the Boe-Bot Robot Kit web page.· The best place to start with continuous rotation servo control is Chapter 2, Activity #3, #4, and #6.

One final note, it is not difficult to modify a standard servo to be a continuous rotation servo.· Use these words in Google: Modifying Hobby Servo Motors for Continuous Rotation.· However, I don't recommend it.· A standard servo is nice to have around for a variety of projects, and the price of the continuous rotation servos is much less than any standard hobby servo.· The Parallax Standard Servo is the least expensive·hobby servo·I know of, and it's $12.· You can get two continuous rotation servos for about the same price.

Post Edited (Andy Lindsay (Parallax)) : 6/7/2006 1:01:55 AM GMT