[time-nuts] Form factor

[Robert LaJeunesse]

The I2C bus is moderately well defined for the hardware interface, but hardly at 
all at the software level. This could be problematic for a system that supports 
multiple hardware configurations. It also uses single ended signalling which 
creates RF noise if not treated extremely carefully. Might I suggest the use of 
a more robust, extensible interface with strong software support and 
differential signalling? The best that comes to minde is 2-wire CAN based on the 
CANopen standard. See http://en.wikipedia.org/wiki/CANopen and 
http://www.canopen.us/

Bob L.

________________________________
From: Chris Albertson <albertson.chris at gmail.com>
To: Discussion of precise time and frequency measurement <time-nuts at febo.com>
Sent: Wed, December 22, 2010 2:58:10 PM
Subject: Re: [time-nuts] Form factor

The use of i at c that I proposed was ONLY for module-to-module
communication.  I wrote that none of the internal chips in a module
were to be exposed to the i2c bus.  A module may very well have it's
own internal bus but that design detai needs to be hidden from the
rest of the system.

In an open system built with modules yu realy, have to be careful to
never expose the inner working on a module.  Else other modules come
to depend on the internal design of other modules and then you can
never upgrade of replace any of them because you have a circular
dependency loop or likely even multiple loops.  So we have to be
carfull to never expose the kind of chip or it's internal bus address
between modules.

...