Subject:
|
Re: "Servo" Driver for NQC
|
Newsgroups:
|
lugnet.robotics
|
Date:
|
Sat, 2 Feb 2002 17:09:55 GMT
|
Original-From:
|
Steve Baker <sjbaker1@airmail.NOSPAMnet>
|
Reply-To:
|
sjbaker1@NOSPAMairmail.net
|
Viewed:
|
1068 times
|
| |
|
|
Matthias Jetleb wrote:
>
> > But it doesn't need to. The 'power' settings built into the RCX firmware
> > are already using pulse-width modulation to adjust the amount of power
> > the motor delivers.
>
> Yes, but only one of 8 settings (why not all 256??? I don't understand
> why they limited this). Sometimes only 8 settings doesn't give you
> enough finesse.
That was explained earlier. They are using an 8 bit number to store
the *pattern* of the modulation. With 8 bits, there are only 8 different
ratios of 1's to 0's - and one of those is to have no power at all. Hence
there are seven power levels.
I suppose they could have used a byte to count the duration of the on period
and the duration of the off period - but for some reason they chose not to
implement it that way. Without analysing the software in a lot more detail
than I'd care to do, it's hard to know whether that was a good design decision
or a bad one.
Personally, I doubt that you could really tell the difference between power
levels that are just one step apart - so it's probably irrelevent.
----------------------------- Steve Baker -------------------------------
Mail : <sjbaker1@airmail.net> WorkMail: <sjbaker@link.com>
URLs : http://www.sjbaker.org
http://plib.sf.net http://tuxaqfh.sf.net http://tuxkart.sf.net
http://prettypoly.sf.net http://freeglut.sf.net
http://toobular.sf.net http://lodestone.sf.net
|
|
Message is in Reply To:
 | | Re: "Servo" Driver for NQC
|
| (...) Yes, but only one of 8 settings (why not all 256??? I don't understand why they limited this). Sometimes only 8 settings doesn't give you enough finesse. Matthias Jetleb (23 years ago, 2-Feb-02, to lugnet.robotics)
|
18 Messages in This Thread:
 
 
- Entire Thread on One Page:
- Nested:
All | Brief | Compact | Dots
Linear:
All | Brief | Compact
|
|
|
|
