I'm back with tests... the weird "pre-start" condition of SCL is now gone... Thanks for the effort Mark!

For all of you though, here are some stats:

100K Ohm resistor ends up being anywhere from 25-35uS of pullup time on the SDA line. This equates roughly as 27Khz to 40KHz xfer rate. Ouch. I'm not sure how this worked before as Mark's code generates a hi-low time of about 1.3uS and 2.6uS. Basically, the clock "frequency" is about 280Khz right now.

With my 5.1K resistor installed, I have a pull-up time of 1.9uS, so there's plenty of setup time before clocking in the next bit.. I don't have such warm fuzzies about the stock configuration.

So I thought I would mention it to you guys here. I'm kinda surprised the things on the bus are happy at all. No wonder I was seeing the "fan control error" messages I was.

I have lots of screen shots off my scope if anyone is interested in seeing before and after "pics".

Cheers,

-Ben