> -----Original Message-----
> From: Olin Lathrop [SMTP:olin_piclist@EMBEDINC.COM]
> Sent: Friday, August 16, 2002 1:03 PM
> To:   PICLIST@MITVMA.MIT.EDU
> Subject:      Re: [PIC]: Which mu-C Best For I2C?
>
> > Yowza!! 100 slaves?  Well, I can give you one recommendation right
> > away.  IIRC the maximum recommended bus length is 10cm.
>
> Recommended in a particular situation perhaps, but IIC has no official
> maximum bus length.  The hard limits are the maximum capacitance (400pF if
> recall), and the maximum sink current required to lower a bus line to
> logic
> 0 (around 3mA, again from memory).  These parameters and the maximum clock
> rate will dictate the maximum bus length in your case.  Note that you get
> to
> chose the clock rate.
>
Philips even has an app note showing the use of I2C over very long distances
using their dedicated I2C buffer.  IIRC they managed to get it to work over
a mile.

Mike

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