From: Dave Hart <davehart_gmail_exchange_tee@davehart.net>
To: esr@thyrsus.com
Cc: thumbgps-devel@lists.bufferbloat.net
Subject: Re: [Thumbgps-devel] Article -- Macx-1: GPS receiver with standard USB connector and PPS support
Date: Thu, 10 May 2012 07:28:38 +0000 [thread overview]
Message-ID: <CAMbSiYDsk4TDh7eCCQaU6yqMxsGdxiY5+8USm1KFm1Xsj9H+iw@mail.gmail.com> (raw)
In-Reply-To: <20120510063125.GC12435@thyrsus.com>
On Thu, May 10, 2012 at 6:31 AM, Eric S. Raymond <esr@thyrsus.com> wrote:
> Dave Hart <davehart_gmail_exchange_tee@davehart.net>:
>> I had a vague recollection GPSD could use PPSAPI where it's available.
>> If that's true, when GPSD is using PPSAPI, isn't it restricted to
>> using carrier detect in practice?
>
> Which line the PPS arrives on is a hardware feature of the GPS completely
> decoupled from anything PPSAPI has any control over.
>
> There's no code-complexity cost for being flexible. Here's what the
> code looks like:
>
> #define PPS_LINE_TIOC (TIOCM_CD|TIOCM_CAR|TIOCM_RI|TIOCM_CTS)
I understand gpsd's flexibility when providing PPS timestamping using
TIOCMIWAIT. My impression, without auditing a bunch of code, is that
PPSAPI implementations in OSes commonly are watching only the CD line.
That's the case with the few I've looked at closely, although they're
not among the most commonly used.
Cheers,
Dave Hart
next prev parent reply other threads:[~2012-05-10 7:29 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-05-09 6:43 Jau-Yang Chen
2012-05-09 15:23 ` tz
2012-05-09 16:39 ` Dave Taht
2012-05-09 16:47 ` Eric S. Raymond
2012-05-09 16:55 ` Dave Taht
2012-05-09 17:02 ` Eric S. Raymond
2012-05-09 17:12 ` tz
2012-05-09 17:50 ` Ron Frazier (NTP)
2012-05-09 18:21 ` tz
2012-05-09 18:35 ` Dave Taht
2012-05-09 20:41 ` Ron Frazier (NTP)
2012-05-09 20:46 ` Dave Taht
2012-05-09 20:58 ` Ron Frazier (NTP)
2012-05-09 20:59 ` Dave Taht
2012-05-09 22:57 ` Ron Frazier (NTP)
2012-05-09 21:14 ` Eric S. Raymond
2012-05-09 22:30 ` tz
2012-05-09 19:43 ` Dave Hart
2012-05-09 20:37 ` Eric S. Raymond
2012-05-09 21:03 ` Dave Hart
2012-05-09 21:18 ` Ron Frazier (NTP)
2012-05-09 21:38 ` Eric S. Raymond
2012-05-09 22:02 ` Dave Hart
2012-05-10 6:31 ` Eric S. Raymond
2012-05-10 7:28 ` Dave Hart [this message]
2012-05-10 14:55 ` tz
2012-05-10 17:59 ` Eric S. Raymond
2012-05-09 21:20 ` Eric S. Raymond
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