Re: [Gumstix-users] I2C Pullups?

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

Hi Jason,

On Mon, 10 Jan 2005 15:09:39 -0600, Jason von Nieda <ja...@vo...> wrote:
> Hi all. I've seen some discussion on the list regarding pullup resistors
> for the I2C bus and I'm going to be experimenting with this some
> tonight. I don't see a place on the Gumstix or Waysmall board where I
> can easily get at 3.3v without some serious surface mounting skills that
> I don't possess. What I was thinking of doing, and I'm sure this will
> make the real engineers in the audience cringe, is using one or two of
> the other available GPIO lines on the Waysmall as a pull up power
> supply. I'd just add a few lines to my init scripts to set the lines as
> output and then have the resistors go from those lines tied together to
> the I2C bus lines.

I'm pretty sure that the voltage regulator on the waysmall board
is3.3v. You can see the schematic here:
http://www.gumstix.org/tikiwiki/tiki-index.php?page=POWER_JACK

In this picture:
http://www.davehylands.com/linux/gumstix/Case-Fit/HPNX0079.html
the voltage regulator is the little five pin chip immediately to the
left of the power supply, and the top pin on the side with just two
pins, would correspond the 3.3v signal (You should check with a
multimeter to be sure).

You should be able to solder a wire onto there to get your 3.3v.

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