From owner-freebsd-usb@FreeBSD.ORG Thu Nov 30 20:02:03 2006 Return-Path: X-Original-To: freebsd-usb@freebsd.org Delivered-To: freebsd-usb@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id 6E3DE16A7B5 for ; Thu, 30 Nov 2006 20:02:03 +0000 (UTC) (envelope-from chris@vindaloo.com) Received: from corellia.vindaloo.com (corellia.vindaloo.com [64.51.148.100]) by mx1.FreeBSD.org (Postfix) with ESMTP id EE6FB43CF9 for ; Thu, 30 Nov 2006 20:00:18 +0000 (GMT) (envelope-from chris@vindaloo.com) Received: from yavin.vindaloo.com (yavin.vindaloo.com [172.24.144.34]) by corellia.vindaloo.com (Postfix) with ESMTP id 6E82F5CD4; Thu, 30 Nov 2006 15:00:21 -0500 (EST) Received: from dagobah.vindaloo.com (dagobah.vindaloo.com [172.24.145.68]) by yavin.vindaloo.com (Postfix) with ESMTP id 05962253A1; Thu, 30 Nov 2006 15:00:20 -0500 (EST) Received: from localhost.vindaloo.com (localhost.vindaloo.com [IPv6:::1]) by dagobah.vindaloo.com (8.13.8/8.13.8) with ESMTP id kAUJxv9f001148; Thu, 30 Nov 2006 14:59:57 -0500 (EST) (envelope-from chris@vindaloo.com) From: Christopher Sean Hilton To: Bo Granlund In-Reply-To: <20061125090630.GC17442@sushi.tonnikala.net> References: <20061125032050.GA17442@sushi.tonnikala.net> <4567D5A9.5010602@totalterror.net> <20061125090630.GC17442@sushi.tonnikala.net> Content-Type: text/plain Date: Thu, 30 Nov 2006 14:59:56 -0500 Message-Id: <1164916796.1054.6.camel@dagobah.vindaloo.com> Mime-Version: 1.0 X-Mailer: Evolution 2.6.2 FreeBSD GNOME Team Port Content-Transfer-Encoding: 7bit Cc: freebsd-usb@freebsd.org Subject: Re: USB GPS receiver as reference clock X-BeenThere: freebsd-usb@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: FreeBSD support for USB List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 30 Nov 2006 20:02:03 -0000 On Sat, 2006-11-25 at 11:06 +0200, Bo Granlund wrote: [ snip ] > > I loaded the uplcom module and reattached the gps receiver. And then I > linked /dev/cuaU0 to /dev/gps1. Cat'ing /dev/gps1 returns NMEA data, but > when I try start ntpd this comes to the logs: > > Nov 25 10:58:24 battleangel ntpd[798]: refclock_nmea: time_pps_create > failed: Inappropriate ioctl for device > > Do you have any clue as to why it complains about an inappropriate ioctl? > > Thanks for the uplcom pointer, now I got somewhat forward in my attempts to > make ntpd work with my usb receiver. > GPS Clocks for ntp synchronization need to do something called "Pulse Per Second". This involves toggling the state of one of the serial control lines once every second to indicate the edge of a measured time period. I'm not sure if ntp can sync to a clock using nmea data alone. It's possible since the nmea sentences have the full time information embeded withing them but I don't know how accurate it would be. There may be an ntp configuration option for gathering time data from within the nmea sentence itself but I'm not familiar enough with ntd to actually set that up. -- Chris