Subject:
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Re: Varying the output voltage?
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Newsgroups:
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lugnet.robotics.rcx.legos
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Date:
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Sat, 14 Jun 2003 17:53:51 GMT
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Viewed:
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3086 times
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This is what I noticed, comparing the two systems
with BrickOS
One thing that I noticed was at the lower voltages the needle on my
multimeter
wavered around a little and it tended to steady at the higher power
levels
All of the readings were taken while plugged into a 9v AC adapter. The
internal sensor of the rcx read 8402 mv
power level mesured voltage
15 2v
45 4.5v
75 5.75
105 6.25
135 6.75
165 6.9
195 7.0
225 7.1
255 7.25
The battery reads at 8420 mv
Power Level Mesured Voltage
1 3.75
2 4.5
3 5.25
4 5.9
5 6.5
6 7
7 7.4
8 7.6
So there is a couple things, the most starteling is that it appears that
the standard firmware can put more volts through the output. This may be
because the robot running standard firmware had a higher battery charge,
although I'm not sure on the internal workings of the rcx, maybe it puts
the batterys in pararellel along with the direct DC, which would account
for the lower voltage readings on the legOS robot. (the brickOS read
7670 mv without the wall adapter and the standard firmware red about
8290 mv).
Another thing I noticed, just qualitatively is that when the motor is
stalled on the brickOS robot the pitch changes as the power increases
while on the rcx with standard firmware the pitch remains constant.
Another thing, while the brickOS firmware is capable of going at slower
speeds, it does not seem to have quite the range of torque as the one
with standard firmware.
If any of you have any idea on how to make it emulate the standard
firmware, I'm interested to know. Also do you know how the brickOS
firmware does it, if it doesn't use the 8ms system?.
-Aaron
On Sat, 14 Jun 2003 08:08:32 GMT
Juergen Stuber <stuber@loria.fr> wrote:
> "Bluey" <Wolf_and_eagle@spamblock.yahoo.com> writes:
> >
> > The overall answer is, the RCX is set up only to have
> > three voltage levels: +9, 0, and -9.
> > The basic options there are On, Off, and Reverse.
>
> Actually there are four, sort of, as for 0 there are float
> (contacts separated, infinite resistance) and brake
> (contacts shorted, zero resistance).
>
> The standard firmware switches rapidly between on and float
> (each cycle takes 8ms), which reduces power but not speed,
> unless you have a load.
>
> If you switch between on and brake you can regulate speed,
> but this might strain the motors more.
>
> > Now by electronically varying the Pulse Width you get 8/7
> > (not sure) levels of power in each direction instead of
> > the original 3, that is all you get.
>
> The number of levels depends on the software, the standard
> ROM supports 8 (0-7) which correspond to 1-8 on out of 8ms.
> I think brickOS has many more levels.
>
>
> Jürgen
>
> --
> Jürgen Stuber <stuber@loria.fr>
> http://www.loria.fr/~stuber/
>
> > rot 13 "fr"
> "se"
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Message is in Reply To:
 | | Re: Varying the output voltage?
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| (...) Actually there are four, sort of, as for 0 there are float (contacts separated, infinite resistance) and brake (contacts shorted, zero resistance). The standard firmware switches rapidly between on and float (each cycle takes 8ms), which (...) (21 years ago, 14-Jun-03, to lugnet.robotics.rcx.legos)
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