Removing Glamo from GTA02 (Was: Welcome)
Rask Ingemann Lambertsen
rask at sygehus.dk
Sun Apr 19 20:12:04 CEST 2009
On Sun, Apr 12, 2009 at 10:40:36PM -0700, Steve Mosher wrote:
> Interesting thought. Its probably a tall order to get the community up
> to speed on the whole phone building business building process. I'd
> start with a simple task.. GTA02 -G.. just to give people a taste of
> what one is up against.
Sure. When taking out the Glamo, we lose some I/O which needs replacement:
g1) An LCD interface.
g2) An MMC/SD interface.
g3) 1 GPIO for LCD_RESET.
We gain a little as well:
G4) 1 interrupt pin (2442 LCD interface) connected to 3D_INT.
G5) 1 GPIO (2442 camera interface) connected to 3D_RESET.
g3) and G5) cancel each other out.
As to g1), the only realistic other place to attach the display is to the
2442's LCD interface. With G4) now unused, we need to find replacement for
l1) 2 GPIOs for PCB revision.
l2) 2 GPIOs for G1_CS and G2_CS (2 accelerometer SPI chip selects).
l3) 1 GPIO for HDQ (battery monitoring).
l4) 1 GPIO for PIO_5 (something with the Bluetooth module).
I count 15 unused, unconnected GPIOs on the schematics, so I'll assume we
can find replacement GPIO for l1)-l5).
That leaves g2). We basicly have two options:
1) Use the 2442's unused SPI interface 0 for MMC/SD(HC) cards. Supposedly
this can be done. The AR6001 can then remain on the 2442's SDIO interface.
2) Use the 2442's SDIO interface for MMC/SD(HC) cards. The AR6001 will then
connect to the unused SPI interface 0 instead. Werner made the latter work
and the former works on the GTA01.
The SPI interface is slower than the SDIO interface, so which to choose
depends on which of MMC/SD(HC) or WLAN you think is most important. I'd go
with 2) since with a page-on-demand system, fast disk I/O is needed for low
user interface response times and there are already complaints in that area
while we have yet to hear anybody complain about slow WLAN (which also isn't
used as much?).
Removing the Glamo needs no new components as far as I can tell. Thus
everything ought to fit inside the case as well as on the PCB. Rerouting of
the signals going to the display and to the AR6001 seems to be the only
possible obstacle, but we have extra space with all the address and data
lines to the Glamo gone.
So the remaining question: What is holding back the "GTA02.1"? Lower WLAN
speed? Difficulty pricing the new device? Wanting to get rid of the
inventory of Glamos? Wanting to get rid of the NOR chip also while we are at
it? In addition to s/Calypso/MC75i/? No management type around to tell
engineering to "just get the blasted thing out of the door"? ;-)
Rask Ingemann Lambertsen
Danish law requires addresses in e-mail to be logged and stored for a year
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