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Turning the SD card off periodically to fix the cross talk(emf) issue
is a good thing. Especially if it allows the GPS receiver to function
properly and reduce power consumption on the SD card subsystem. <br>
<br>
I don't think they are talking seconds here but milliseconds. If the
SD card is on once every 10 ms for a couple ms, that should provide
ample time to read or write data to the card and also provide ample
time to get good signal from the GPS satellite. I'm making up those
values, the real time periods are for the HW engineers to work out.
All hardware and software designs are a set of compromises. <br>
<br>
At least thats how I see a possible solution done. I've done similar
things in other embedded hardware.<br>
<br>
Scott<br>
<br>
<br>
<br>
BlueStar88 wrote:
<blockquote cite="mid:487E2C15.80409@Xenobite.eu" type="cite">Andrew
Bennett schrieb:
<br>
<br>
<blockquote type="cite"> From reading between the lines on some of
the e-mails from OpenMoko staff, it seems that the interference with
the GPS receiver was caused (at least in part) by the SD reader being
always-on, apparently because the SD firmware is still incomplete or in
beta, much like the rest of the OpenMoko firmware. The fix appears to
be to enhance the SD reader to only turn on when necessary. From where
I sit, that's a two-fer! GPS gets fixed and the SD reader gets
enhanced to a more complete state. I'm happy :)
<br>
</blockquote>
<br>
Ahmm... to only turn the reader on when nescessary? Sorry, but that
sounds like to be just a "work around" to me, not an enhancement to a
more complete state. It sounds like selling a bug and it's work around
as a feature we all have waited for..
<br>
If I got this right, it still remains to be a reception mess, if the
reader will turned on on demand (for reading map-data for example). So
where exactly is the enhancement? Not to have to pull out the SD card
for using GPS/getting fix? Nice, but thats not enough.
<br>
If the GPS reception qualitiy drops for - lets say - 50%, while
accessing map data on the SD-card, I risk to loose the connection to
the satellites in case of having any bad (environmental) conditions.
I'll loose precision at least. Thats very bad for driving in big cities
with tons of obstacles around, where the pure navigation feature and
it's maximum reliability is really needed for the driver. Permanent
SD-card read access while reading map data is surely to expect for
normal usage! It's not about just not beeing able to watch a movie from
SD-card while GPS'ing, it's about the strong need for the GPS/SD
hardware - in combination!
<br>
Sorry, but dynamically switching off the reader or clocking it down
somehow is no real option, it is a serious failure in function for
heavy routing application requirements.
<br>
<br>
To be honest, I personally expected a working mobile in the very basic
hardware meaning, but with trillions of *software* issues of course.
Almost all (very rough assumption) GTA02-people are having this issue
now, even GTA01-users are coming out with confirmations, so why it was
not detected (nor digged deeper) by personal full range use before mass
production? I'm not whining, I'd just like to understand it to some
degree.
<br>
Before someone suggests: I don't like the 'fallback' idea of using an
external antenna, since it is very unhandy for bike and walk usage.
Additionally the MMCX-jack will not like the permanent (often) mount
and unmount procedures it'll cause.
<br>
<br>
My current thoughts are two sided. On one side I don't like to hurt the
really great (!) project by returning the hardware. On the other side I
fear, that this issue cannot be fixed to have the initially expected
behavior.
<br>
<br>
I hope this bug gets busted *effectively*! :)
<br>
<br>
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