[Gta04-owner] gpsd software

NeilBrown neilb at suse.de
Mon Dec 5 22:47:19 CET 2011


On Mon, 5 Dec 2011 07:11:35 +1100 NeilBrown <neilb at suse.de> wrote:


> 
> This 'toggle' nature of the standby line makes it hard to write an 'rfkill'
> driver to powerup/powerdown the gps :-(
> 
> It appears that you can send a SiRF command over the serial line to force a
> power-off (though I haven't tested yet).  If that works, I plan to get the
> 'rfkill' to pulse the line at power-on and arrange some udev script to send
> the power-off command when the rfkill switches to 'off'.

Unfortunately it doesn't work.

The power-off command is only supported for "GSW3 and GSWLT3  version 3.2.5 or
above" and my GPS reports a version of:

GSWLT3.0.0.SDK_3.1.01.00.SDKLT001P1.00

So it looks like pulsing the on/off line is the only way to turn it off.

If we carefully keep count of all pulses and make sure to turn it off before
reboot we should be able to reliably know the state of the GPS and so know
when to pulse the line.  But if the system crashes and reboots, then we
cannot know what state it was in.

So it may turn out that we need to make the gpio available to user-space
just-in-case, but hopefully we can avoid ever having to use it...

NeilBrown


> 
> Then the gpsd script would just 
>    rfkill block gps
> or
>    rfkill unblock gps
> 
> which is nice and generic.
> 
> NeilBrown

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