gpsd + ubx

[Florian Kiera]

Heyo all,

I've been debugging gpsd input/output since I ran into some miracles regarding gpsd and my M8P's. The command I used for this was "gpsd -n /dev/ttyACM0 -N -D 5".
After starting gpsd it will recognize my selected serial device as u-blox device which is fine. Than it sends some dialog to the M8P requesting UBX-MON-VER (line 58-59 and 62-63) and sets the rate of different messages (line 64-83) along with setting the UART output/input (line 60-61).
Sources: attachment gpsd_startup.txt, gpsd_ubx.ods, https://www.u-blox.com/en/docs/UBX-13003221 (p 314 (VER), 184 (MSG), 211 (PRT))

Why does gpsd set the UART input/output protocol on start up? If polling the UART's (01) was the target why not using b5620600010001(checksum) (p 211 of the document from u-blox)?

Running "ubxtool -p CONFIG -P 20.30" doesn't seem to be a poll request only either (ubxtool_call.txt: output of "gpsd -n /dev/ttyACM0 -N -D 5" while "ubxtool -p CONFIG -P 20.30" is running).
As is also does on starting gpsd, it asks for a SET/GET b5620600140003000000d0080000802500002700010000000000c2d1 (03 is USB port this time) (line 89-90).
Sources: same as above + ubxtool_call.txt (also logged with "gpsd -n /dev/ttyACM0 -N -D 5")

Again wouldn't be b5620600030001(checksum) the better choice especially in the situation we just want to poll and not set?

I am not 100% certain if those UBX-CFG-PRT request just have a poll purpose or actually supposed to change the protocol input/output to for example UBX only out, all (UBX+NMEA+RTCM3) in.
Nor I am even close to an expert in ubx to actually know for sure what the GET means in the SET/GET request.
The documents explanation made me up to the thought that the wrong message type might've been used if you want to poll only. (which I think ubxtool -p CONFIG supposed to do)

Regards Florian

gpsd_startup.txt
Description: Text document

ubxtool_call.txt
Description: Text document

gpsd_ubx.ods
Description: application/vnd.oasis.opendocument.spreadsheet