Re: [gpsd-users] how to send control string (command) to device with <CR><NL> included in string

[Stoner, Howard (US COM)]

Hell Gary,  Thanks for your reply!

...

>> I am trying to figure out how a local application (running linux on an 
>> embedded SoC) can send a command to my GPS device

> Sadly gpsd does not do a good job of this.  Most people that care usually 
> patch the copy of gpsd to send their fave setup strings.

>> From reading the gpsd daemon documentation, it sounds like sending a 
>> message via the Control Socket connection, of the form 
>> "!/dev/ttyxx=$PMTK..." should do this.

> I've never tried, nor remember anyone else doing so.  If you can grab git 
> head we can work on this with you.
  
 I can probably mod the '!' command within handle_control to remove the 
'snarfline()' call for my purposes, since I know that whenever I use that 
command I will be supplying exactly what the device needs in its command 
string..


>> I also tried doing this with the 'gpsctl' client, which only works if 
>> I have gpsd NOT connected to the device at the time.

> Well, that would be a bug.  Sadly also a dark and dusty corner of the gpsd 
> code.  Some people have gotten that to work, but never fed back their 
> procedure.  But any reason not to send the string before starting gpsd?

My intent is to handle 'mode' changes in the gps device, particularly power 
standby / restart commands, without stopping and restarting gpsd, but I may be 
able to handle it with either a shutdown/restart of gpsd, or via the control 
socket mod referred to above.


Thanks again,
Howard