[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [gpsd-users] GPS reporting wrong time to SHM

From: Alexander Carver
Subject: Re: [gpsd-users] GPS reporting wrong time to SHM
Date: Fri, 07 Sep 2012 14:33:17 -0700
User-agent: Mozilla/5.0 (Windows NT 5.1; rv:15.0) Gecko/20120824 Thunderbird/15.0

On 9/7/2012 05:23, Eric S. Raymond wrote:
Alexander Carver <address@hidden>:
I think the safest thing to do would be to document this as a known SiRF.
firmware bug.  Can you identify the SiRF firmware version from the log?

Yes, the receiver identifies the software as:

Version 2.3.2-GSW2-2.05.024-C1Prod1.1

Does this new FAQ entry match your experience?

<h1 id="timelag2">Why is my GPS time off by exactly one second?</h1>

<p>This can happen if (a) there has been a recent <a
adjustment</a>, (b) you have a version of GPSD that was built before
the adjustment, and (c) your GPS doesn't ship the current leap-second
offset in a form GPSD can see.  If this happens, GPSD will fall back
to a compiled-in default that is off by one</p>

<p>Some SiRFs have a particularly insidious version of this.  They are
supposed to ship a MID52 sentence (which GPSD knows how to interpret)
containing the current leap-second offset.  But there is at least one
firmware revision that ships a damaged version of MID52 with a garbled
start sequence or a zero length field.  This GPSD cannot handle.</p>

<p>The bad revision is 2.3.2-GSW2-2.05.024-C1Prod1.1; there may be
others.  Suspect this if you have persistent off-by-one errors. If you
are able to identify other bad firmeare versions, please let us
know about it.</p>

That's pretty much it.

Out of curiosity, where in the code does gpsd pick up the messages from the serial port prior to sending it along to the giant switch switch statement in the SiRF driver? I might tinker with the message collector and see if I can snag a broken MID 52.

reply via email to

[Prev in Thread] Current Thread [Next in Thread]