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DPRG: Linx RF Modules

Subject: DPRG: Linx RF Modules
From: David Philip Anderson dpa at io.isem.smu.edu
Date: Thu Nov 11 00:00:37 CST 1999


Seems like momentum is building toward a group purchase of Linx Technologies
RF modules, like those used on SR04 to implement the telemetry back
channel.   I would be happy to demonstrate SR04's radio link at the next
DPRG meeting, if there is interest in such.

I purchased the "evaluation kit" a couple of years ago, for about $99.
It included a pair of transmitters and a pair of receivers, all four on
418 MHz, and a couple of brief (<10 page) manuals.  This did not include
(at that time) any evaluation board.

They were pretty easy to get working, essentially just a straight RS-232
connection on each end (HC6811/Max232 -> Tx -> Rx -> laptop COM port) 
with a resistive divider and diode on the transmitter end.

The robot sends a continuous stream of 80 byte ascii characters at 2400
baud.  This includes things like time stamp, battery voltage, sensor readings,
odometry calculations, state variables, and so forth.  These are displayed
on the receiving end or tee'd off to a file for later perusal. 



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