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Re: [gpsd-users] 1 PPS and Ubuntu11.10 serial port problem

From: Robert Livingston
Subject: Re: [gpsd-users] 1 PPS and Ubuntu11.10 serial port problem
Date: Thu, 02 Feb 2012 09:24:33 -0800
User-agent: Mozilla-Thunderbird (X11/20090103)


The PPS is there (driving a rubidium standard and a timing interface) but the Resolution-T output level is CMOS, approximately 2 V. That is undoubtedly the problem with the RS232, and it is relatively simple to remedy in hardware. II had hoped that an industrial computer RS232 UART might be more forgiving, but I just tested it using a +-5V (short run) RS232, and it does not even respond to that.

Thanks for the tip. GPSD is an amazing piece of work, and your user group support is extraordinary.


Gary E. Miller wrote:
Yo Robert!

On Wed, 01 Feb 2012 19:46:11 -0800
Robert Livingston <address@hidden> wrote:

Thanks for the comments. Swiping the testing version of 3.4.1 from Debian testing (along with a couple of other packages) runs on Ubuntu 11.10 and the "not-online" errors disappear.


NTP works with the GPS as before, and as Hamish points out, that may
be sufficient.  However, I'd like to use the 1 PPS in addition but
the serial port never seems to see the CD pin signal.  In previous
(older version) cases, the CD interrupt was noted in the -D5 list,
and I see none now.  Have you seen cases where the UART is masking
the interrupts, an is there a way to see if that is the case?

The most common problem is the PPS level is not real RS-232.  Are
you sure your output is going from -12V to 12V and back again?

Also some GPS need to be told to output PPS signals.

So best to put an oscilloscope on the pin if you can.

Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97701
        address@hidden  Tel:+1(541)382-8588

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