Ah ha...i did not know that a servo motor only needs to be "updated" around 20ms . I thought it needed a continous pulse.. Again i pose the question though, o n a basic stamp i assume they do that, update the pulse around 20ms, but how can i check if my program is running when 20ms has elapsed? timmer intterupt? cau se what if my main loop is longer then 20ms, it wont get bak to the line to upda te the servo's in time correct? On Thu, 18 Nov 1999 13:13:07 -0600 Dan Creagan wrote: >No. The PWM for a servo is different than a continuous PWM >signal needed for a regular motor. Hobby servos have their >own electronics and only require a moderately frequent >signal to keep the motor going. The signal, for most 90 >degree motors, is between 1 ms and 2 ms with a gap of about >20 ms between updates. A signal of 1.5 ms will drive the >servo to the middle position. The exact specs are just a >little bit different for different servos. > >After updating the servo, there is a wait time before the >next update of about (avg) 20 ms. > >That kind of a signal can be sent as part of the general >chores of the checking sensors and outputting other >information. > >For a good summary of how to command the servo, see >http://www3.sympatico.com/donroy and look at the >instructions for the 1stBot kit. > >Dan > >-----Original Message----- >From: Mike M >To: PICLIST@MITVMA.MIT.EDU >Date: Thursday, November 18, 1999 6:17 AM >Subject: [OT] Re: PWM background > > >>How do basic stamps 1 or 2 run servo motors? Dont they use >16C56 that also does not have a pwm port??? >> >>On Wed, 17 Nov 1999 17:26:23 -0500 Sean Breheny > wrote: >>>At 08:55 AM 11/18/99 +1200, you wrote: >>>>I haven't done this myself yet but I can't see why a PWM >of lowish >>>>freq and not too high a resolution couldn't be run from >the timer >>>>overflow interrupt. >>> >>> >>>Yes, it certainly can be done. I did it in a robotics >project. Take a look at: >>> >>>http://www.hobbyrobot.com/info/SoccerBot/index.html >>> >>>and specifically the PIC source code >>> >>>http://www.hobbyrobot.com/info/SoccerBot/code/bot11.asm >>> >>>It is true that I only achieved a PWM frequency of a few >kHz at 7-bit >>>resolution (I think the maximum possible rate for a 10MHz >PIC was about >>>10kHz for 8 bit resolution). >>> >>>Sean >>> >>> >>>| >>>| Sean Breheny >>>| Amateur Radio Callsign: KA3YXM >>>| Electrical Engineering Student >>>\--------------=---------------- >>>Save lives, please look at http://www.all.org >>>Personal page: http://www.people.cornell.edu/pages/shb7 >>>mailto:shb7@cornell.edu ICQ #: 3329174 >>> >> >>Send someone a cool Dynamitemail flashcard greeting!! And >get rewarded. >>GO AHEAD! >http://cards.dynamitemail.com/index.php3?rid=fc-41 > Send someone a cool Dynamitemail flashcard greeting!! And get rewarded. GO AHEAD! http://cards.dynamitemail.com/index.php3?rid=fc-41