Subject:
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RE: Another update for WIRRL
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Newsgroups:
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lugnet.robotics
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Date:
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Tue, 22 Oct 2002 14:08:27 GMT
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Original-From:
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Rob Limbaugh <RLimbaugh@greenfieldgroup.com(antispam)>
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Viewed:
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799 times
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I just noticed at least one glaring error with the new schematic...
Say, for argument, an RCX sends "1001", which, in IR, would be "0110". The IR
detector of WIRRL would do nothing for the first bit ("0"), but the next bit
("1") should be sent over the RFTX, and, according to the current
logic/schematic, it is. However, I never disabled the line between the RFRX and
the Oscillator, so the RFRX will receive the transmission from the RFTX (because
all are same frequency). This would make IR = 1 and RF = 1. According to the
truth tables, priority will be given to RFRX data and the third bit of IR ("1")
would never be sent.
Apparently, while creating the truth tables, I gave consideration to this... I
just never included it in the schematic.
-----Original Message-----
From: Rob Limbaugh
Sent: Tuesday, October 22, 2002 2:45 AM
To: lego-robotics@crynwr.com
Subject: Another update for WIRRL
To those interested,
I've made a new schematic (WIRRL Rev. 2a) using a better TX/RX pair (Linx LC
Series) and I think I've found a possible better solution for handling flow
of data. This new diagram eliminates three transistors and replaces the
4001 Quad-NOR with a 74HC00A Quad-NAND.
Out of nowhere, it dawned on me that I should use a truth table to figure
out how to move the data. I've included the truth table information and
logic diagram at the bottom of the page.
Same link as before: http://www.abs-robotics.com/projects/wirrl.htm
Maybe I'll have time this weekend to actually build it...
- Rob
PS - Just as before, I don't claim this circuit works... I haven't built it,
so I don't know. I'm still learning.
----- Original Message -----
From: "Rob Limbaugh" <rlimbaugh@greenfieldgroup.com>
To: <lego-robotics@crynwr.com>
Sent: Monday, October 21, 2002 12:38 AM
Subject: Project WIRRL Update
> Hello everyone,
>
> WIRRL stands for "Wireless Infra-Red Radio Link".
>
> Creating each leg of the RF link independantly isn't really a problem • (once
> you have a reliable 38kHz IR carrier wave). The problem is eliminating • link
> feedback by controlling the direction of the conversation.
>
> Because it had been a couple months since I was last able to play with
> things, I decided I should probably document where I am now. (Spending
> yesterday going back over my notes was sort of a drag...) Then, I had • this
> radical idea of sharing things (what a concept!?).
>
> [The real story: I couldn't find everything. The stuff I did find was • out
> of order or in multiple places. I couldn't read some of my own notes, and • I
> had to rebuild some things so I could remember what they did!]
>
> So, for those interested:
> http://www.abs-robotics.com/projects/wirrl.htm
>
> Be warned... the current schematic probably won't work if you build it
> (matter of fact, I'm willing to bet it won't). The diagram looks like • it's
> made from different resources... that's because it is.
>
> Today I was working with a possible half duplex communication switching
> solution, which is set to be controlled by a 4001 NOR gate. A 200us delay
> is set for both sides of traffic. So, when the RX side is re-transmitting
> IR data, the 4001 is supposed to turn off the data line for the IR decoder
> (which feeds the RF TX) and hold it off 200us after the line goes low so
> feedback doesn't occur. This is where I'm currently stuck. Sadly, I'm • not
> an electronics guru, so it will take me some time to figure things out.
>
> Any guidance would be welcomed!
>
> - Rob
>
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Message has 2 Replies:
 | | Re: Another update for WIRRL
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| Instead of worrying about the half duplex communication, wouldn't it just be easier to have tranceiver at two different frequencies? If I am missing something, go ahead and say so. I know very, very little about electronics. Timothy (...) (22 years ago, 22-Oct-02, to lugnet.robotics)
| | | Re: Another update for WIRRL
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| I'm watching your postings with some interest as I'm also very interested in implementing are wireless RF<->IR interface for the RCX, and have been eyeing the Linx transmitter/receivers too. One question - could some of the transmit/receive (...) (22 years ago, 22-Oct-02, to lugnet.robotics)
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