where to connect for extension ?

Al Johnson openmoko at mazikeen.demon.co.uk
Sun Nov 23 13:40:06 CET 2008

On Sunday 23 November 2008, Alessandro Sappia wrote:
> On Sat, Nov 22, 2008 at 11:46 AM, Al Johnson
> <openmoko at mazikeen.demon.co.uk> wrote:
> > On Friday 21 November 2008, Alessandro Sappia wrote:
> >> Hi
> >> Me and some friends wants to connect the freerunner to some kind of
> >> sensor. We saw that the debug connector give us the SPI bus.
> >> is it a good choice ?
> >
> > It has been suggested in the past. I don't know if anyone's actually
> > tried it yet though.
> which ones are the connection used in some other projects ? I wasn't
> able to fount any
> project involving some hardware extension.

Several options have been talked about, but the only one I've seen documented 
was the DAB radio one soldered to the USB port.

> >> is there a point where to take power near there (the debug connector
> >> doesn't export it...
> >
> > R4701 and R4702 next to the debug connector have one end on the IO 3.3V
> > line, but may not be a good place to pull power from. R7802 on the other
> > side of the speaker has the 3.3V supply for the accelerometer which may
> > be better. It probably depends on your power supply requirements though.
> >
> > I assume you've found the schematics:
> > http://downloads.openmoko.org/schematics/GTA02/
> Yes, we have the schematics, but we really miss a good hardware hacker
> between us :)
> the 3.3V supply seems fine. le'ts give it a try. we have to give power
> to an OPAMP.

That doesn't narrow the requirements  down much ;-) What is it you're trying 
to do?

> I didn't check if the soundcard is easily reachable, but we may
> substitute the ADC on the
> external sensor with it (opamps are always needed to get a bigger signal).

Could be an option, again depending on what you're doing.

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