I've gone a couple of meters and have not tried more. This issue is really the logic 0->1 transition. This is because the transistors are open-drain and use an external pullup resistor. Pull-down is fast because the transistor sinks a lot of current. Pull-up is with a fairly "wimpy" resistor. You can reduce the resistor value to about 50% of its recommended value. The way to test is with an oscilloscope. With the logic high level being set by a resistor, the logic high is more prone to noise than regular logic. The fact that the whole system is synchronous helps to reduce that, but it requires some care. Jim On Tue, 13 Dec 2005 16:23:19 -0800 James Washer <washer@trlp.com> wrote: > I've read that 3 or 4 meters is fine for TWI at all but > the fastest bit rates... Is that what you all have found? > > How far have you gone at various bit rates? > > - jim > > > ------------------------ Yahoo! Groups Sponsor > --------------------~--> > Get Bzzzy! (real tools to help you find a job). Welcome > to the Sweet Life. > http://us.click.yahoo.com/KIlPFB/vlQLAA/TtwFAA/dN_tlB/TM > --------------------------------------------------------------------~-> > > > > Yahoo! Groups Links > > > > > > > --------------------------------------------------------------- The Think Different Store http://www.thinkdifferentstore.com/ For All Your Mac Gear ---------------------------------------------------------------
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Re: [AVR-Chat] "bus length" for TWI?
2005-12-14 by Jim Wagner
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