At 07:13 AM 8/18/2008, you wrote:


> > -----Original Message-----
> > From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On
>Behalf
> > Of John Day
> > Sent: 18 August 2008 02:12
> > To: Microcontroller discussion list - Public.
> > Subject: Re: [PIC] PIC-Friendly "serial expansion bus"
> >
> > At 07:52 PM 8/17/2008, Forrest W Christian wrote:
> > >5) Slaves should be able to be detected by the master, and should not
> > >have to have addresses set via dip-switches or other means.
>Globally
> > >(factory set) unique addresses are ok (aka 1-wire style),
>dip-switches
> > >are not (aka i2c is not an option).
> >
> > Nothing that you have said actually rules out I2C. If you use the
> > 'general call' address, you can discover the devices on the bus and
> > then dynamically assign an I2C address. In reality it depends almost
> > entirely on how dynamic you little network is, if it is highly
> > dynamic then this may result in a slow start-up each time.
>
>One thing that would tend to make it undesirable IMO is the complexity
>of implementing a slave in software, especially if you want it to work
>at reasonable speeds.  If the SSP/MSSP is available on the slave devices
>then it's not a problem, but having the heardware available on the
>slaves is less likely than on the master IMO.

Maybe this is more of a PIC limitation than an I2C limitation! I 
don't know about the Microchip range but in the Atmel products the 8 
pin ATtiny25/45/85 have hardware I2C (master or slave).

Regards, John


>Regards
>
>Mike
>
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