AVR-Chat

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

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
> 
> 
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