Re: [offtopic] Re: I2c was: Cobalt Micro (was Re: Build your own Mo therboards)
Simon Vogl (simon@tk.uni-linz.ac.at)
Thu, 10 Sep 1998 08:13:34 +0200 (MET DST)
> [SNIPPED]
> > Eh? Are we talking about $I^{2}C$? It sounds like you are talking about
> > Ethernet. I could have sworn that I remembered I2C being a clocked
> > tri-state bus (or whatever the correct terminology is), with automatic
> > backoff (multiple devices can start transmitting at once: the first one to
> > notice the bus differing from what it is sending simply stops
> > transmitting.
>
> You can write and read at the same time. You don't know that somebody
> else is attempting to write while you are.
>
>
> The bus is unharmed by this, and one message is guaranteed
> > to go though.
>
> The bus is permanently hung until both persons who thought they were
> the master, reinitialize their controllers.
>
> No messages are guaranteed to go through.
Seems more to me that the controllers are brain-dead, not necessarily the protocol.
I know the spec, as I have written the Linux driver, but I would not want to implement
arbitration for my parallel port adapter :)
Another story is my pcf 8584 controller who does arbitration detection ( although I had no
chance to heavily test it yet).
As far as I can see, the i2c-bus is out there, like it or not. So please share your
experience with us (in a more i2c-bus driver related environment - email me - this thread
is already long enough ).
Simon
--
http://www.tk.uni-linz.ac.at/~simon/private/i2c
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