Re: Sending commands to device while gpsd is running

[Filip Kubicz]

Hi Gary,

No debugging of the receiver is needed. I know it works when I send a certain 
UART payload.
I just want to achieve the same payload to be sent through gpsd, to avoid 
contending with gpsd for serial port access.

gps_send() unfortunately only sends the buffer from client to gpsd, but gpsd 
doesn't forward the buffer to the device.

>From inspecting gpsctl, I see that gpsctl "low-level mode" means "bypass 
>gpsd". And it doesn't have a way to write to the device through gpsd.
gpsctl uses session.device_type->control_send() to ship the control message. 
But it must be called from within gpsd session, not from a client using libgps. 
Similar thing (I think) could be achieved by modifying handle_gpsd_request() to 
actually ship the buffer to the device if it has a certain format.

So I guess I have to write to the serial port outside gpsd and make sure I'm 
not doing it in the initial setup phase when gpsd might be sending some 
commands to the device.
If there is another method to achieve sending a control message to a device 
from a client, please advise.

Thanks,
Filip

filip@kubicz.engineer
tel. (+48) 697 088 078



---- On Wed, 13 Apr 2022 20:06:50 +0200 Gary E. Miller <gem@rellim.com> wrote 
----

 > Yo Filip! 
 >  
 > On Wed, 13 Apr 2022 10:41:14 +0200 
 > Filip Kubicz <filip@kubicz.engineer> wrote: 
 >  
 > > I have found that gps_send() format should follow the command for 
 > > from gpsd(8) page. 
 >  
 > The devil is in the details. 
 >  
 > I looked for an example, but no gpsd code does anything like that. 
 > So you are chariing a new swamp. 
 >  
 > I suggesst you try methods known to work, as shown by the gpsd 
 > client code.  Look at zerk, bxtool, gpsctl, etc. 
 >  
 > > However there is still no response: 
 > > 
 > > $PQTMVEHMSG 
 >  ^^^ 
 >  
 > There is your problem.  Quectel. 
 >  
 > Quectel is "quercky".  No way I can debug it without my having a "working" 
 > device. 
 >  
 > I suggest that you turn the debug level WAY up.  Maybe 8 or even 9. 
 >  
 > RGDS 
 > GARY 
 > --------------------------------------------------------------------------- 
 > Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703 
 >     gem@rellim.com Tel:+1 541 382 8588 
 >  
 >         Veritas liberabit vos. -- Quid est veritas? 
 >  "If you can't measure it, you can't improve it." - Lord Kelvin 
 >