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 Robotics / 19302
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Subject: 
RE: Another update for WIRRL
Newsgroups: 
lugnet.robotics
Date: 
Tue, 22 Oct 2002 14:08:27 GMT
Original-From: 
Rob Limbaugh <rlimbaugh@greenfieldgroup.=StopSpammers=com>
Viewed: 
758 times
  
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




Message has 2 Replies:
  Re: Another update for WIRRL
 
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
 
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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