Thanks for all the replies. I finally decided to use a conventional BJT with about 10K into the base.  Similar to the MOSFET it probably consumes a few more nA but the pulses are infrequent. This is working quite well.

I am using a voltage divider to send pulses back to the PIC. Again very little current for this application.

Cheers
Fritz

On 12/18/2012 12:11 PM, Neil MacMunn wrote:
Hi Fritz,

If you just need to shift one signal you can do so with a mosfet and a couple of resistors. Have a look at sheet 6/10 in the latest Chestnut schematic.

http://pubs.gumstix.com/boards/CHESTNUT/R3596/B30005.pdf

-
Neil


On Mon, Dec 17, 2012 at 8:17 PM, Fritz Sonnichsen <fsonnichsen@whoi.edu> wrote:
I am observing a TBOI/OVERO board with a scope and pin 17 appears to
send 0v, 1.8v when toggled with GPIO. It is interfacing with a CMOS/PIC
that requires (I think) a 2.5V  threshold to go from low to high.
I want to use an IC Buffer or inverter such as the CD4049UB, CD4050B.
Sound like a good idea? Interested in what others do.

Thanks
Fritz


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