On 8/7/2012 2:47 AM, PICdude wrote:
> In the 3.3V-->5V direction, it seems the 5V RX1 input (18F24K22) is a
> Schmitt trigger, and the electrical specs for that in the datasheet
> are minimum input-High voltage of 0.8Vdd, so 4.0V, and thus the 3.3V
> signal won't work.
>
Eh?    How is an open drain output from the 3.3V side *not* going to=20
meet the 4V input spec on the 5V side, if the line is pulled up to 5V?
Unless I'm missing something, the 5V  tolerant feature of the 3.3V part=20
means you can just pull both lines up to 5V.
But if the 3.3V input side clamps the 5V output, the 5V side would get=20
confused when it's master?

Joe W
--=20
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