Subject:
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Re: multi-device output controller
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Newsgroups:
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lugnet.robotics
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Date:
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Fri, 26 Mar 1999 16:30:48 GMT
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Original-From:
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alex wetmore <alex@IHATESPAMphred.org>
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Viewed:
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905 times
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On Fri, 26 Mar 1999, Lou Sortman wrote:
> Joel Shafer wrote:
>
> > What about a real time circuit that routed the output power to one of eight
> > output ports depending on the PWM. That way it only takes one output port
> > on the RCX and up to three (out of 24) motors could be running at the same
> > time.
>
> And where are you getting motor drive power from? I assume you want the selected
> motor to run at full power, not at 1/8, 1/4, etc. I'm afraid you're still stuck
> consuming the extra output for power unless you use a separate power source.
With a seperate battery box (from 8735 for instance) you could power the
output full time. In this case you'd probably want to map it to something
like this:
off - off
1 - output 1 fwd
2 - output 1 rev
3 - output 2 fwd
4 - output 2 rev
5 - output 3 fwd
6 - output 3 rev
full - output 4 fwd
(if there is a 7 then you could get 4 outputs in fwd and reverse).
You would get a max of 9 (or 12) outputs, but I think that would
be plenty for most RCX-type robots (I still really haven't had to
go beyond 3 outputs, but I've mostly built vehicles).
alex
--
Did you check the web site first?: http://www.crynwr.com/lego-robotics
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Message has 2 Replies:
 | | Re: multi-device output controller
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| (...) There are 8 levels of PWM, so fwd/rev for 4 devices is possible. I originally wanted a separate power input to allow a full 8 levels for each device. This would allow the controller to operate ANY device designed for the RCX ports and not (...) (25 years ago, 26-Mar-99, to lugnet.robotics)
| | | Re: multi-device output controller
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| There is no need to waste PWM levels on reverse. You can set the RCX motor output to reverse speeds as well, giving you 7 outputs (fwd and rvs) instead of 3 1/2. You need a bridge rectifier anyway; you might as well exploit it to indicate direction. (...) (25 years ago, 26-Mar-99, to lugnet.robotics)
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Message is in Reply To:
| | Re: multi-device output controller
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| (...) And where are you getting motor drive power from? I assume you want the selected motor to run at full power, not at 1/8, 1/4, etc. I'm afraid you're still stuck consuming the extra output for power unless you use a separate power source. (25 years ago, 26-Mar-99, to lugnet.robotics)
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