HOWTO: scons gpsd build incorrect and ntpshmmon gives no data

MIKE MAJOR ossfm at
Thu Aug 9 02:15:51 UTC 2018


    On Wednesday, August 8, 2018 12:01 AM, Gary E. Miller via devel <devel at> wrote:
On Wed, 8 Aug 2018 03:15:54 +0000 (UTC)
MIKE MAJOR via devel <devel at> wrote:

>> In the HOWTO section "Live-test the GPS", the reader is instructed to
>> build gpsd using: $scons timeservice=yes magic_hat=yes nmea0183=yes
>> fixed_port_speed=9600 fixed_stop_bits=1

> Not really.  That is just an eplanation for what clockmaker --build
> does.

I guess that is where I misunderstood. I'm used to a HOWTO explaining the steps to perform a certain task. The steps are laid out in order. The reader then follows along, repeating the steps on his/her computer to achieve the task. 

It was not clear to me that the expectation is to use clockmaker to perform the tasks and read along only for instructional purposes. I thought I could choose to do one of two things: take the easy way and run clockmaker to save some typing OR take the detailed way and type the commands one by one. 

>> When running gpsmon /dev/gpsd0, it is expected that there are
>> scrolling lines at the bottom showing raw data. I didn't get that.

> Not good.  Is your GPS really on /dev/gpsd0?  Is your GPS running

I see my mistake now. I read the first 2 lines below to be the same when they are not: 
# ./gpsd/gpsmon /dev/gpsd0
# ./gpsd/gpsd /dev/gpsd0 
# ./gpsd/ntpshmmon
The result was that I didn't execute the second line. gpsd was not running. Therefore,  ntpshmmon had not data to show. 

Everything is working correctly now. 

>> Cross checking with the clockmaker script showed that 2 options are>> missing from the HOWTO text: ublox=yes mtk3301=yes

> Not really.  The script is for NMEA mode.  To keep things simple.

clockmaker has this:      scons timeservice=yes magic_hat=yes nmea0183=yes ublox=yes mtk3301=yes fixed_port_speed=9600 fixed_stop_bits=1 The HOWTO has this:   scons timeservice=yes magic_hat=yes nmea0183=yes fixed_port_speed=9600 fixed_stop_bits=1
I was pointing out that the two don't match. In my subsequent testing, clockmaker produced a correctly working gpsmon, where the HOWTO text did not. 

>> Paul, can you submit a fix for that too?

> No fix here.  Just something different.  Something not intended
> by the clockmaker script.

Right, clockmaker is fine. The HOTWO needs to be fixed to match the clockmaker script. The HOWTO text is missing the two options. Even if the text is instructional only, it should match the clockmaker content. Someone may read the text only (and not read clockmaker) which will leave their build non-functional. We do want the HOWTO text to match clockmaker, right?

>> I am performing all steps by hand and checking against the clockmaker
>> script. The script installs some s/w packages that the reader has not
>> been instructed to do at this point in the HOWTO text.

> The point is that the reader NOT install them, but have clockmaker
> install them.
I understand that now. I'll add that to my notes of things to improve in the HOTWO for clarity's sake. 

Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
    gem at  Tel:+1 541 382 8588

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