>> If you're talking about connecting two devices which are running off of
>> different power supplies, and you don't want them to have a common
>> ground, you could try using opto-isolators on the i2c pins. Make sure
>> your opto's can switch faster than the bit rate you're running your i2c
>> bus at.

> Whoa. On second thought, that whole opto-isolator idea might not work
> since i2c is bi-directional (on the same pin). You might be able to do
> it on an SPI bus where input and output each have dedicated pins. You
> may still be able to do it with opto's but it will be hairier than it
> originally seemed.

You were OK the first time. You can do I2C across optos. It just requires 4
of them and a little mental gymnastics to arrange them to work properly.

Steve.

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  Very funny Scotty.  Now beam down my clothes.
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Steve Baldwin                Electronic Product Design
TLA Microsystems Ltd         Microcontroller Specialists
PO Box 15-680                email: steveb@kcbbs.gen.nz
New Lynn, Auckland           ph  +64 9 820-2221
New Zealand                  fax +64 9 820-1929
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