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Re: [gpsd-dev] [Patch Submission] $GPVTG w/magnetic course
From: |
Gary E. Miller |
Subject: |
Re: [gpsd-dev] [Patch Submission] $GPVTG w/magnetic course |
Date: |
Tue, 12 Jun 2018 19:23:50 -0700 |
Yo teyrana!
On Mon, 4 Jun 2018 11:58:41 -0400
teyrana <address@hidden> wrote:
> Okay, after a fair bit of discussion, Here's new patch for $GPVTG
> parsing:
Progress.
> ## Patches:
> - 1 of 2 - https://pastebin.com/uGG9jH30
This worries me:
+ if (session->newdata.mode < MODE_2D) {
+ session->newdata.mode = MODE_2D;
+ mask |= MODE_SET;
+ }
I see nothing about GPVTG (http://aprs.gids.nl/nmea/#vtg) that tells us
the GPVTG tells us the GPS fix mode is at least 2D. Got a citation?
Maybe make it a comment in the code?
I'm not sue this is the right place for :
+ // request to report an output message
+ mask |= CLEAR_IS;
+ mask |= REPORT_IS;
Running 'scons check' shows why:
-{"class":"TPV","mode":3,"time":"2010-02-05T08:50:37.000Z","ept":0.005,"lat":53.919546833,"lon":27.500650000,"alt":265.100,"epx":235.985,"epy":133.116,"epv":178.020,"track":277.7200,"speed":0.130,"climb":0.000,"eps":471.97}
+{"class":"TPV","mode":3,"time":"2010-02-05T08:50:37.000Z","ept":0.005,"lat":53.919546833,"lon":27.500650000,"alt":265.100,"epx":235.985,"epy":133.116,"epv":178.020,"track":277.7200,"speed":0.130,"climb":0.000}
Notice "eps" is getting lost. Most likely because of a premature CLEAR_IS
so the entire data for the cycle could ne get accumulated.
Getting CLEAR_IS and REPORT_IS right is hard (maybe impossible). If
possible, you only want them on the last message of a cycle.
Spend some time looking at 'scons check' to ensure your patch has only
positive effects.
> - 2 of 2 - https://pastebin.com/m0i19iWV
Looks good. I applied it, minus the driver_nmea.c part, plus some whitespace
changes.
I also added magtrack to the gpsd_json(5) man page.
RGDS
GARY
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Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
address@hidden Tel:+1 541 382 8588
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Re: [gpsd-dev] [Patch Submission] $GPVTG w/magnetic course, Gary E. Miller, 2018/06/14