Re: [Gumstix-users] Part # of robostix 3.3v<->5v shifter?

[Dave H. <dhy...@gm...>]

Hi Chris,

> The right fix to this problem would be to actually fab a custom PCB
> and take other sorts of steps to minimize the capacitance.  Seeing as
> how we have to demo our work on Wednesday, I chose the "cheap kludge I
> didn't think would hurt anything and thought might help" approach and
> added a 5kohm pullup resistor to each of SDA and SCL on our PCB.  I'm
> a bit embarrassed by this solution, but I haven't seen a failure in
> the twenty minutes of continuous testing I've done so far, and I'm
> pretty sure this shouldn't actually hurt anything.  If I'm wrong about
> that, please do reply.

If it works, I'd say go for it. The only disadvantage of having too
much pullup (every pullup resistor "strenghtens" the pullup amount),
is that it gets harder to pull the signal to ground.

--
Dave Hylands
Vancouver, BC, Canada
http://www.DaveHylands.com/