How does the servo work?

stevebzzzzz · 2011-07-17 13:44

Hi,

I'm a little confused as to how the servo works in the BS2 stamp kit. I (Maybe Incorrectly) assumed that a constant HIGH on the input would result in a constant motion. In fact, I plugged the white control into VDD and only got a slight jerk. So am I to understand that the servo responds only to high/low pulses as opposed to a constant HIGH? And if so, why?

Cheers.....

Leon · 2011-07-17 13:50

http://en.wikipedia.org/wiki/Servomechanism#RC_servos

stevebzzzzz · 2011-07-17 14:04

Leon wrote: »

http://en.wikipedia.org/wiki/Servomechanism#RC_servos

:blank:

Wow, now I'm sorta even more confused! So essentially, there is a "BS2" inside the servo controlling all of this feedback stuff huh ?

Mike Green · 2011-07-17 14:22

There's some kind of cheap small microcontroller in there although it could be done all with analog devices and was at some point in the evolution of R/C servos. It's cheaper and simpler now with a cheap small microcontroller.

stevebzzzzz · 2011-07-17 14:28

Mike Green wrote: »

There's some kind of cheap small microcontroller in there although it could be done all with analog devices and was at some point in the evolution of R/C servos. It's cheaper and simpler now with a cheap small microcontroller.

Wow, a small microcontroller inside the servo? It must be about the size of that tiny surface mounted led on my Homework board

This is all so mind boggling. I guess that servo design is a whole science by itself. And the fact that it even reverses directions when I manually pulse the VDD is making my head explode

Cheers....

Publison · 2011-07-17 14:32

Read this, and if you have any questions, please post.

http://www.parallax.com/Portals/0/Downloads/docs/prod/motors/900-00005StdServo-v2.1.pdf

Mike Green · 2011-07-17 14:37

Yep. Here's one example of a 6 pin device in an itsy-bitsy package, 750 words of flash for instructions, 24 bytes of data, a 2 channel analog to digital converter and a timer, all for less than 40 cents.

stevebzzzzz · 2011-07-17 14:45

Wow, 2 x 3 x 1 Millimeters! Is that even visible? Plus an 86 Page Manual! So at that level, you're almost programming molecules to move around huh

How does the servo work?

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