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Re: [gpsd-users] PPS MID 52 (0x34) working?


From: Alexander Carver
Subject: Re: [gpsd-users] PPS MID 52 (0x34) working?
Date: Tue, 05 Jun 2012 21:39:48 -0700
User-agent: Mozilla/5.0 (Windows NT 5.1; rv:12.0) Gecko/20120428 Thunderbird/12.0.1

On 6/5/2012 15:58, Gary E. Miller wrote:
Yo Alexander!

On Tue, 05 Jun 2012 15:31:46 -0700
Alexander Carver<address@hidden>  wrote:

If you have a lot of time to spend on it see if you can improve it,
but many have already tried.

I did specify the speed earlier but I'm running SiRF binary (not
NMEA) at 38,400.  The GPS is emitting five messages every second plus
two additional messages every couple minutes.  The entire set of
messages fits inside one second although the position relative to the
PPS pulse edge does move a little when those once per two minute
messages show up (mainly the sky list).

Sorry, obviously you are on SiRF binary to get the MID 52.  But just
because it is bianry does not mean that it is all fixed length.

And what are those 2 messages?  If we can turn them off, without losing
something else, then that would help.  Otherwise an ugly hack would be
to ignore the MID 52 if we can determine that it is not the first in the
current second.  Unlikely we can get the vendor to fix it, and if we
could there would still be a bunch of bad units in the field.

One of the two messages is the visible sky map (all sats above the local horizon). I need to check the other but it is something also related to the almanac. I don't think I can turn them off on this particular SiRF chip (GlobalSat). Using SiRFDemo on Windows, I can see that MID 52 does emit at the PPS pulse. The rest of the messages come in around it on their update cycles. The offset from the PPS pulse varies for all the other messages. Sometimes it comes very quickly after PPS and sometimes very late (but always before the next pulse).


NetBSD zs8530tty.c or zs.c sparc sun4c architecture

Ah, yes, you did mention you were on NetBSD, don't have a copy here.
Does the driver support ioctl(TIOCMWAIT)?

Since you are on BSD, I think ckeuthe prefers his PPS to go directly
to the kernel.  Not sure how *BSD does that.

No TIOCMWAIT in sparc/BSD serial that I could see. Kernel PPS is enabled on this system (kernel recompiled with the PPS option enabled). That's present and working properly.



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