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Subject: 
Re: Another update for WIRRL
Newsgroups: 
lugnet.robotics
Date: 
Tue, 22 Oct 2002 21:43:03 GMT
Viewed: 
724 times
  
What's a "proxy messenger"?

Couldn't the reflection problem be solved by placing a barrier in between
the emitter and receiver?

Timothy


In lugnet.robotics, "Rob Limbaugh" <RLimbaugh@greenfieldgroup.com> writes:
Just in case people are a bit confused by the schematic, the circuit =
would be needed for each device that will participate in an RF bridge.

I abandoned the idea of using two different frequencies because:

1)  As soon as you attempt communication between more than two devices, =
one device would have to be a proxy messenger.

2)  Using two different RF frequencies doesn't solve the =
IR-reflection-feedback problem that would exist.

A single frequency solves #1 (BTW, the current IR communication is =
single frequency:  38kHz).  Using logic between the IR side and the RF =
side solves direction switching and #2 by disabling the appropriate data =
path.

One solution could involve using a programmable logic device with 4 I/0 =
lines (at least two in and two out).  If data comes in from the RFRX =
first, then ignore any incoming data on IRRX until ~1.67us after =
incoming RFRX data ceases.  If data comes in from the IRRX first, then =
ignore any incoming data on RFRX until ~1.67us after incoming IRRX data =
ceases.  With the right PLD, the I/O line used for IR-out could be =
pulsed at 38kHz without an external oscillator circuit.  Even in this =
case, the one RF frequency could be used.

Another option would be to modify the "Hardwired RCX" solution Peter =
Balch came up with (http://www.abs-robotics.com/other/hardware.htm).  =
There are arrows in the diagram indicating data direction.  What you =
could gain by using different RF frequencies is the ability to do =
full-duplex communication (which may require customized firmware and/or =
PC software to unlock that ability).

Perhaps I should add a "pros and cons" section to the page for the =
various ideas...  The two ideas listed above have several other design =
issues to consider beyond what is mentioned here.

I don't know much about electronics, either.  Part of the reason for =
pursuing this endeavor is because I'm getting bored with "Connect red =
wire from J5 to spring 34".  So, like you, I would hope that if I'm =
making a wrong turn, someone would point it out to me.

- Rob




Message has 1 Reply:
  Re: Another update for WIRRL
 
I should have removed the word "messenger". After all, doing something by "proxy" would imply a messenger-type role. What I meant was, for DeviceA to send a message to DeviceB, they would have to use some sort of proxy or router between them (the (...) (22 years ago, 23-Oct-02, to lugnet.robotics)

Message is in Reply To:
  RE: Another update for WIRRL
 
Just in case people are a bit confused by the schematic, the circuit would be needed for each device that will participate in an RF bridge. I abandoned the idea of using two different frequencies because: 1) As soon as you attempt communication (...) (22 years ago, 22-Oct-02, to lugnet.robotics)

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