New Life in Openmoko Phones

[Rask Ingemann Lambertsen]

On Tue, May 19, 2009 at 10:52:22AM -0400, Stefan Monnier wrote:

> That still doesn't explain why removing one of the two accelerometers is
> a good idea.  What is the benefit?  Why not remove them both?
> Is it that all the programs that use the accelerometers (as of now) only
> use one of the two?  Is it that having two accelerometers introduces
> layout difficulties?  Is it that there aren't enough interrupt lines on
> the SoC to properly support the two accelerometers? ...

   I don't think so. We already have both EINT8/GPG0 and EINT16/GPG8
reserved for the second accelerometer, but not connected it to EINT16/GPG8
(R1547 = NC). Last time I counted[1], there wasn't a shortage of interrupt
or GPIO pins.

[1] http://lists.openmoko.org/pipermail/gta03/2009-April/000074.html

   If we're really going to mess with the accelerometers, why not move them
off the SPI1 bus and onto GPIO pins? We're currently using the bitbanging
GPIO_SPI driver anyway. That way, we could keep a GTA01/GTA02 compatible
debug connector (because WLAN could use SPI1 instead of SPI0).

> I actually have the same question for the audio-amp: why remove it?
> But that one is a bit more complicated, because I'm not sure what is
> this "audio-amp" anyway (is it the thing that drives the
> headphone plug?)

   It drives either the headphone speakers or the bottom handset speaker,
depending on the presence of the headphone plug. It's the LM4853 (U4101 on
page 7 of the schematics). IIUC, the GTA03 was going to drive both from the
WM8753L sound chip directly as suggested in the WM8753L datasheet. I wanted
to compare the output power of the two, but I can't find the exact LM4853
variant we're using.

-- 
Rask Ingemann Lambertsen
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