Re: [gpsd-users] Changing the GPS update rate with gpsd

[Alexander Carver]

On 2016-03-16 16:48, Deven Hickingbotham wrote:
> On 3/13/2016 1:15 PM, Bo Berglund wrote:
>>> >You may be correct on the kernel issue.
>>> >
>>> >However, my thinking was that on both Wheezy and Jessie I can change
>>> >the GPS update rate.  I wrote a Python app that does this and I can see
>>> >the confirmation response code and see the packets speed up or slow
>>> >down.  All of this is done through /dev/ttyAMA0.  It is only when I
>>> >restart gpsd that things go wrong under Jessie and 3.11.  So my
>>> >suspicion was that gpsd might be now resetting the GPS in 3.11.
> 
>> Or your script might not actually be able to do what you think it does
>> if invoked by systemd during startup of Jessie...
> 
> Right now none of this is in a script.  I'm just executing commands in
> the terminal with plenty of time between commands.  Something like:
> 
> sudo service gpsd stop
> execute script or Python app to change GPS update rate
> confirm update rate has changed
> wait
> sudo service gpsd start
> cgps -s (and observe the update rate)
> 
> Under Wheezy and gpsd 3.6 this works.  Under Jessie and gpsd 3.11 it
> does not work.  Same results using an identical Pi.
> 
> There has been a suggestion that it is a Jessie issue.  Perhaps so, but
> I just don't see why the OS would be resetting the GPS update rate???
> 
> I tried to be clever and install gpsd 3.6 under Jessie.  This exceeded
> my skill level ;-)

Since this is Jessie, have you checked the /etc/default directory for
any gpsd related files?  It's possible that there's some related
commands in that file (or at least their configurations which play into
the systemd script) that are resetting the port.  Or perhaps the gpsd
package was compiled to send a reset.  Add the -b command line flag to
the gpsd options in /etc/default which will keep gpsd from sending data
to the GPS receiver.  If that fixes the problem then it's the way gpsd
was compiled for Jessie.  If it doesn't fix the problem then the new
systemd service script is doing something silently.