GPS performance issues on GTA02v5

Daniel Willmann daniel at
Thu Apr 24 17:43:19 CEST 2008

On Thu, 24 Apr 2008 00:57:27 -0300
Werner Almesberger <werner at> wrote:

> [ Removed gta02.internal. No need to create tons of moderation
>   requests ;-) ]
> Shawn Rutledge wrote:
> > Can the phone's battery provide backup power?  Or how about a
> > supercap?  Can this be fixed in a future board rev?
> If all the battery does is to retain data we can retrieve via UBX
> and to keep the clock running, we're probably better off doing all
> this in software. Daniel already seems to pretty close to having
> solved that issue.

Using FixNow we can probably achieve similar results while the device
is running. The GPS will automatically sleep and turn off the RF part.
Though EXTINT0 we can request a fix solution once or just have the GPS
provide one periodically. The reason I mention this is that when
loading the data we need to set the time pretty accurately and that
might pose a problem. Not sure about that yet.

> By the way, layout changes have a fairly long turn-around time. If we
> decided on some urgent change today, it would take something like 2-3
> months until boards with that change would actually reach customers
> in volume.

> That is, if that change doesn't introduce problems, e.g., in the SMT
> process. "Odd" components like batteries sometimes do ...

I understand the implications, but I prefer we look into it instead of
just sticking our head in the sand and waiting for the problem to go
away. It might still be that it's just the fault of the prototypes I
have available. But we wont figure that out until we test the other
devices. :-)

Daniel Willmann
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 189 bytes
Desc: not available
Url :

More information about the openmoko-devel mailing list