Subject:
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Re: RCX & RIS, a fading glory?
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Newsgroups:
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lugnet.robotics
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Date:
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Fri, 7 Feb 2003 00:06:01 GMT
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Original-From:
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Steve Baker <(sjbaker1@airmail.)Spamcake(net)>
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Viewed:
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553 times
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PeterBalch wrote:
> > You could still *OPTIONALLY* have support for human-friendly names...
> > cute graphical thing
> > LEGO ... just have clear building instructions
> > each device can electrically 'buffer' the signal before passing it
> > on to the next device in the chain, you don't get signal degradation.
>
>
> I don't believe that degradation would be a problem. Even TTL-level "RS232"
> works well over tens of metres.
It's not just a matter of distance - it's a matter of the electrical
load on the output of a single device. TTL-type devices have a suprisingly
low limit on the number of inputs they can drive. With a 'bus' type
device, that would limit you to the number of devices you could connect.
My suggested daisy-chain approach would have no such limits.
> I think the cost is higher. The connectors need to be more complex -
> because you have a separate "in" and "out" rather than a common bus. And
> you'd need "Y" connections. The chip needs more I/O pins and more complex
> software: it needs to pass on packets that aren't addressed to it (and
> add/subtract 1 from the address). The chip must be able to receive and pass
> on packets at any time whereas with a well-designed common bus, the chip
> might be allowed simply not to answer if it's busy servicing its
> peripheral.
Silicon is cheap - but I'll agree that a second connector adds to the
cost.
I think a lot depends on who is building this and for what market.
As a small-run geek toy, you could tolerate quite a lot of configuration
hassles in order that you could use off-the-shelf parts.
OTOH, if this is a big run - of Lego Mindstorms-like proportions - then
you can consider specially engineered parts and connectors - but the
configuration has to be incredibly simple.
It's a tough trade-off.
---------------------------- Steve Baker -------------------------
HomeEmail: <sjbaker1@airmail.net> WorkEmail: <sjbaker@link.com>
HomePage : http://www.sjbaker.org
Projects : http://plib.sf.net http://tuxaqfh.sf.net
http://tuxkart.sf.net http://prettypoly.sf.net
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Message has 1 Reply:
 | | Re: RCX & RIS, a fading glory?
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| Despite this thread having become strangely fractured within the lugnet system of threads, and despite the intriguing "what if's" that always get aired when threads like this are allowed to take wing, I have a couple of rather down to earth (...) (21 years ago, 7-Feb-03, to lugnet.robotics)
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Message is in Reply To:
| | Re: RCX & RIS, a fading glory?
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| Steve You're really putting me on the spot aren't you? OK ... (...) Before a download begins, the PC checks whether the named motors exist in the model. If they don't, it offers you the chance to set up a new alias table (which is probably local to (...) (21 years ago, 6-Feb-03, to lugnet.robotics)
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