From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from europa.AD.HartBrothers.Com (unknown [50.46.86.110]) by huchra.bufferbloat.net (Postfix) with ESMTP id 964052006AA for ; Thu, 10 May 2012 00:29:02 -0700 (PDT) Received: from mail-bk0-f43.google.com ([209.85.214.43]) by europa.AD.HartBrothers.Com over TLS secured channel with Microsoft SMTPSVC(6.0.3790.4675); Thu, 10 May 2012 07:29:01 +0000 Received: by bkty5 with SMTP id y5so2147703bkt.16 for ; Thu, 10 May 2012 00:28:58 -0700 (PDT) Received: by 10.204.129.87 with SMTP id n23mr1191012bks.19.1336634938286; Thu, 10 May 2012 00:28:58 -0700 (PDT) MIME-Version: 1.0 Received: by 10.205.142.146 with HTTP; Thu, 10 May 2012 00:28:38 -0700 (PDT) In-Reply-To: <20120510063125.GC12435@thyrsus.com> References: <02af01cd2daf$05b24bb0$1116e310$@navisys.com.tw> <20120509203719.GA3855@thyrsus.com> <4FAADF21.6030907@techstarship.com> <20120509213841.GB4379@thyrsus.com> <20120510063125.GC12435@thyrsus.com> From: Dave Hart Date: Thu, 10 May 2012 07:28:38 +0000 Message-ID: To: esr@thyrsus.com Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable X-OriginalArrivalTime: 10 May 2012 07:29:01.0393 (UTC) FILETIME=[92015410:01CD2E7E] Cc: thumbgps-devel@lists.bufferbloat.net Subject: Re: [Thumbgps-devel] Article -- Macx-1: GPS receiver with standard USB connector and PPS support X-BeenThere: thumbgps-devel@lists.bufferbloat.net X-Mailman-Version: 2.1.13 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 10 May 2012 07:29:03 -0000 On Thu, May 10, 2012 at 6:31 AM, Eric S. Raymond wrote: > Dave Hart : >> I had a vague recollection GPSD could use PPSAPI where it's available. >> =A0If 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. =A0Here'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