Subject:
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Re: Electrical Data Link between 2 RCXs
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Newsgroups:
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lugnet.robotics.rcx.nqc
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Date:
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Mon, 26 Mar 2001 22:49:58 GMT
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Viewed:
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2348 times
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Thanks for the info on the electric datalink. It's a clever idea that I
never would have thought of myself.
It seems to me that you could cut down on your transmission time if you
changed the shape of your pulse train. The pauses between bits don't convey
any intformation. Instead of triggering your counter off a rising edge
(like a telagraph operator sending Morse code), try triggering off any edge.
This would change your message from (For a binary 9):
____ ____ __ __ ____
__ __ __ __ __ ____
Start 1 0 0 1
To:
____ __ ____
__ ____ __ _____
Start 1 0 0 1
Assuming the pauses between bits are 10ms, this saves 40ms per message.
The start pulse also conveys little information. I imagine it is required
to trigger the start of your message receiving routine. Would it work code
the first bit into the start pulse? A long start pulse is a 1, and a short
start pulse a 0.
______ __ ____
__ __ ____
Start1 0 0 1
One ugliness here is that the state of the input flip-flops after each message.
This results in a fairly significant decrease in the message transmission
timing. Assuming the following timings (in ms).
40 Binary 1, Start pulse
10 Binary 0, Pause
20 Binary 0 Start pulse, Minimum time between messages
50 Binary 1 Start pulse
The average time required to transmit a message (two 1's and two 0's) is:
200ms - Start pulse with 4 bits seperated by pauses
160ms - Start pulse with 4 bits
130ms - 4 bits with start delay encoded into first bit
What version of the firmware were you running for your experiments? If you
have the version 2.0 firmware did you try using the event mechanism? Were
you running multiple tasks during your experiments? What effect do multiple
tasks have on the reliability of your software?
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Message has 2 Replies:
 | | Re: Electrical Data Link between 2 RCXs
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| Hi Dean, thanks for your interesting idea for a reduction of transmission time. I will deal with that as soon as possible. Your questions: (...) Version 2.0 (...) No. Do you think that is faster? (...) No, just the transmission program. (...) Good (...) (24 years ago, 28-Mar-01, to lugnet.robotics.rcx.nqc)
| | | Re: Electrical Data Link between 2 RCXs
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| (...) Hi Dean, meanwhile I followed your suggestions and implemented a scheme that uses a pulse scheme like this: ______ ______ ______ __ ______ ______ ___...___ Start Bit3 Bit2 Bit1 Bit0 A bit value of 1 results in a long pulse, a bit value of 0 in (...) (24 years ago, 3-Apr-01, to lugnet.robotics.rcx.nqc)
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Message is in Reply To:
| | Electrical Data Link between 2 RCXs
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| It's me again with the subject "electrical datalink between 2 RCXs" (I posted some articles a couple of weeks ago). This subject may seem trivial but in fact it is not. Dealing with it, I discovered some "unpleasanties" in the general execution of (...) (24 years ago, 26-Mar-01, to lugnet.robotics.rcx.nqc)
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