pontentiometer to control standard servo

sushiandmorihiko

hello,

now i am planning to rotate standard servo by means of 3-pin potentiometer---so when you turn the knob of the potentiometer,the servo will move the same amount and direction with the potentiometer.
is there any way i can do this?--i have seen the servo driver made by robotic world which have this function--so i would like to make my own too.

thank you for the attention

D Faust

You make the RCTIME circuit for photoresistors (see boe-bot book)··and retieve a value.· Next you run this value through some calculations (do some testing to get it right {extremes and middle, If you give me some values I might be able to help if you need it}) and output it through a pulsout command ie: PULSOUT pulsetime

Hope this helps

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TechnoRobbo

If all you want to do is throttle a servo·with a pot·you could use a 555 timer, potentiometer size not important since it's being used as a voltage divider:





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Have Fun


TR

Post Edited (TechnoRobbo) : 10/5/2007 12:24:35 AM GMT

sushiandmorihiko

many thanks to d faust and technorobbo

i have followed your method ,d faust and it works just great. it works really well and sensitive with RCTIME. here is how i did it: with reference to page 208 of boe-bot book
note--you just have to replace the photoresistor with the potentiometer and voila. ok here is the code:

timeleft VAR Word
x VAR Word


DO
HIGH 0
PAUSE 3
RCTIME 0,1,timeleft

DEBUG HOME, "timeleft=", DEC5 timeleft
PAUSE 1

x = timeleft * 16 + 200

PULSOUT 1,x

and the rest is like what d faust has said----again thank you for the advice(i have been trying this for about an hour and finally figures it out).

i would like to try out technno robbo ideas too but i dont have the ics with me right now and it is considerably quite complex but i bet it packs more functions.
looks really cool--is it the kind of circuit that parallax or lynmotion used for driving servos--wow.

you guys seem really experienced in driving standard servo--perhaps until my project is done i will show you guys--hope it is up to your guys standard

thanks a lot guys

sushiandmorihiko

hi guys
what does centering servo actually means?
-is it turning anyway you like and then it will go back to the centre 90 degree for 180 degree rotation servo, or
-is it turning anyway you like and it will go back to where it first started,or
-is it turining anyway you like then it will go back according to the preset angle of your choice.

if anyone knows about centering--pls help me.
i want my servo to move anywhere around and after i m done it will go back to the preset angle or the degrees that i have set in the first place.

i will gladly accept sample codes for standard servo centering

thank you in advance

Beau Schwabe

sushiandmorihiko,

You might find this link useful:
http://forums.parallax.com/showthread.php?p=629063


"centering" is usually referred to servos that have been modified for continuous rotation. It is the position that keeps the servo stationary. You can adjust this position either with a set screw if that option is available, or you can adjust the PULSE width offset that you are sending to the servo through software.

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Beau Schwabe

IC Layout Engineer
Parallax, Inc.

TechnoRobbo

sushiandmorihiko said...
--is it the kind of circuit that parallax or lynmotion used for driving servos--

Can't speak for Parallax but I highly doubt it - that's an old fashioned analog method -both chips are really inexpensive because there from the stone-age.

sushiandmorihiko said...

i bet it packs more functions.

I've used Parallax PSC's in my projects and those are really flexible. You can drive them straight from a PC using their software or from your Stamp.·They don't cost an arm and a leg either. This chip solves the issue of running multiple servos (16 or more if daisy chained)·and not having to worry about your programs timing loop and data storage. It has smooth ramping built in.·

·
http://www.parallax.com/detail.asp?product_id=28023
Here's the PC direct software:
http://www.parallax.com/dl/sw/SetupPSCI.exe


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Have Fun


TR

Post Edited (TechnoRobbo) : 10/5/2007 10:48:50 AM GMT

stephenwagner

Here is another Parallax link, See application #4.

http://www.parallax.com/dl/appnt/stamps/bs1Appnotes.pdf

SJW

D Faust

Glad to help.

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