My earlier post was slightly erroneous.  The setup I was describing was #3
below.  It seems that the setup in question is probably #2.

My system uses two fully-featured transmitters, either can be master or
slave.  Whoever is designated as master has to hold a switch down to turn of
his radio transmitter, and let it up to turn off the other transmitter.  The
protocol is complex, and is a frame-based serial protocol.

Ken

-----Original Message-----
From: Peter L. Peres <plp@ACTCOM.CO.IL>
To: PICLIST@MITVMA.MIT.EDU <PICLIST@MITVMA.MIT.EDU>
Date: Thursday, September 03, 1998 11:31
Subject: Re: How to control an RC car


>There are 3 kinds of master/slave systems on RC Txes that I know of:
>
>1. Dry pots. The pots are read out through a wire each by the master
>transmitter, plus GND. Slave has power off while doing this. This is what
>Sean has indicated. Often has a 5 pin DIN (old system).
>
>2. PWM rules. The slave has power off but receives power from the master
>through the cable. Only the PWM part of the slave works, the Tx is off.
>Often has 5 pin DIN.
>
>3. uC to uC. The computers in the two Txs talk over the cable using a
>proprietary protocol. Almost never uses DIN 5 pin, excepting some older
>semi 'home-made' designs based on 8051 uCs.
>
>hope this helps,
>
>Peter
>