[FSO/SHR] ogpsd/fso-gpsd: can't get 4Hz sample rate

Vasco Névoa vasco.nevoa at sapo.pt
Fri May 15 11:47:36 CEST 2009

Citando KaZeR <kazer at altern.org>:
> Indeed, stopping fso-gps made it work, thanks for the hint. The drawback is
> that you loose all the benefits of fso's gps handling : on demand statup,
> shared access, etc.

That's more or less true. You see, when you stop the fso-gpsd, you  
only stop the "gpsd compatibility layer" daemon. The framework is  
still working.
This means that if you connect to DBUS Gypsy service the framework  
will open the device again. "fso-gpsd" is just another client for the  
Gypsy service.

However, if you are in fact reading directly from /dev/ttySAC1 and  
simultaneously try to read from Gypsy DBUS, the info probably will get  
mangled for both clients. Besides, I forgot to mention this: the  
framework talks binary UBX with the chip, so reading from /dev/ttySAC1  
at the same time gives you UBX binary garbage, not NMEA ASCII text.

So the current workaround that allows us to fully control the chip and  
have NMEA output is to stop fso-gpsd _and_ any other DBUS listener so  
that the framework releases the device; then we can power it off and  
on via /sys to reset the default config (NMEA mode) just in case; and  
then we can safely play around with "cat" and "tail" and  
"/dev/ttySAC1". But as soon as any other app requests the Gypsy DBUS  
service, hell brakes loose.


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