[gpsd-dev] n followed by n in gpsmon

[Eric S. Raymond]

There is a TODO item that reads as follows:

>Hal Murray reports:
>
>   If I run .gpsmon /dev/ttyUSB0
>
>   It starts up in NMEA0183 mode as I expect.
>   "i" switches to SiRF, again, as I expect.
>
>   "n" switches the display to NMEA layout, but the header still says SiRF.
>   Another "n" now says: Device type has no mode switcher.
>   At this point, "i" doesn't do anything.  (no pause either)
>
>The second 'n' is losing information that it shouldn't.
>
>   If I start over and feed it an "f", it starts blinking "Unknown command "f"
>   The logging and display update stops.  After I type another character,  it
>   clears the blinking error message and stars logging/updating again.
>
>Display update should not stop while this is going on.

>From this report, I gather that you started gpsmon on a SiRF running
in NMEA mode.  The 'i' command is expected to start a probe sequence
that, in particular, will flip a SiRF to binary.  It behaved as
expected here.

>   "n" switches the display to NMEA layout, but the header still says SiRF.

That is correct behavior.  The program is telling you that, although
it is receiving NMEA, it hasn't forgotten the fact that the attached
device is a SiRF and you can use SiRF control strings on it.

>   Another "n" now says: Device type has no mode switcher.

Yeah, that was a bug.  What was happening is that when the device
resynched to NMEA it lost its pointer to the SiRF mrthod table.  I
believe it's fixed in the repo version; please test.

>At this point, "i" doesn't do anything.  (no pause either)

That was expected. This command will generally do nothing after the
first time you use it, because the device type will already have been
discovered.

>   If I start over and feed it an "f", it starts blinking "Unknown command "f"
>   The logging and display update stops.  After I type another character,  it
>   clears the blinking error message and stars logging/updating again.

Expected.  After the error it waits for you to acknowledge before
resuming.  I realize this is awkward, but fixing it will need a 
redesign of the gpsmon interface with threading that I'm nervous about
because I fear ncurses will get badly confused.
-- 
                <a href="http://www.catb.org/~esr/";>Eric S. Raymond</a>

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