Re: gpsd losing connection to ublox

[Gary E. Miller]

Yo Niall!

On Wed, 17 Nov 2021 20:24:39 -0800
Niall Parker <stuff@npengineering.ca> wrote:

> > On 2021-11-17 7:21 p.m., Gary E. Miller wrote:  
> > > [..]
> > > I do see this in the tmp3.log:
> > >
> > > gpsd:PROG: gpsd_multipoll(5) DEVICE_UNCHANGED for 11
> > >
> > > That is talking about fd=5, which is your tty.  That is not right,
> > > so I'll dig at that.    
> > 
> > So DEVICE_UNCHANGED is indication the tty stopped for at least 5
> > seconds ?  
> 
> Sort of, more likely a gpsd bug since data is obviously flowing.

I think I see the problem, now that I know your comm port is flooded.
As your "-p STATUS" showed it is 99% full.  Which means you are dropping
messages.

gpsd waits for a pause between epochs:

    if (session->lexer.outbuflen == 0) {
        // beginning of a new packet
    [...]
        session->lexer.start_time = ts_now;
    }    

But since you are flooding the buffers, there is never a pause.  So your bug
is triggering a gpsd bug in a dark corner.

On your end, you need to stop flooding the buffers.  Not sure yet on the
gpsd end.  Need some more direct way to detect messages starts, or end.


RGDS
GARY
---------------------------------------------------------------------------
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
        gem@rellim.com  Tel:+1 541 382 8588

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