From owner-freebsd-arm@freebsd.org Fri Jan 27 06:28:39 2017 Return-Path: Delivered-To: freebsd-arm@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id A2BEECC3DD2 for ; Fri, 27 Jan 2017 06:28:39 +0000 (UTC) (envelope-from tony@tndh.net) Received: from express.tndh.net (express.tndh.net [IPv6:2001:470:e930:1240:20d:56ff:fe04:4c0a]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 72E67B24; Fri, 27 Jan 2017 06:28:39 +0000 (UTC) (envelope-from tony@tndh.net) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=tndh.net; s=dkim; h=Subject:Content-Transfer-Encoding:Content-Type:MIME-Version:Message-ID:Date:In-Reply-To:References:To:From; bh=cEBnUDl8wmr3yCZYPngCvS0m/PB+uWIMJ8aDOXVJc80=; b=AdGJeAbjtzBynbzL1TtQDs+zS+DFuHeDVV3+FhctaqaBtdCMiLTCYVWSQJtV90MYvyccqspbhgpEbNoRRdBfrDhdBe6IkLQDstsbMxnm5VL51is0r7E4m1nXeEjfJOM43oOL4ZlRa43HK3qILAQ3emi6/z0verb7AYvC4vFaQCy4j77D; Received: from express.tndh.net ([2001:470:e930:1240:20d:56ff:fe04:4c0a] helo=eaglet) by express.tndh.net with esmtp (Exim 4.72 (FreeBSD)) (envelope-from ) id 1cX01R-000It9-0N; Thu, 26 Jan 2017 22:28:38 -0800 From: "Tony Hain" To: "'Ian Lepore'" , References: <03a801d2776e$cae997e0$60bcc7a0$@tndh.net> <1485400906.30533.54.camel@freebsd.org> <03bb01d2779d$45d6edd0$d184c970$@tndh.net> <03c101d277ae$70f142c0$52d3c840$@tndh.net> <1485445768.30533.68.camel@freebsd.org> <040101d27816$3f7547b0$be5fd710$@tndh.net> <1485466405.30533.96.camel@freebsd.org> <041a01d2782d$bee11850$3ca348f0$@tndh.net> <1485484023.30533.102.camel@freebsd.org> In-Reply-To: <1485484023.30533.102.camel@freebsd.org> Date: Thu, 26 Jan 2017 22:28:23 -0800 Message-ID: <041c01d27866$95a6ce60$c0f46b20$@tndh.net> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable X-Mailer: Microsoft Outlook 14.0 Thread-Index: AQEImxvIZ6VEPYS1CTeMHuF4SjTdHgFGeuiPAfagOS8BXCmlWAJOLTryAjf7KeUBQ5O/qAF4PpfTAZ9+yj+ic7+uAA== Content-Language: en-us X-SA-Exim-Connect-IP: 2001:470:e930:1240:20d:56ff:fe04:4c0a X-SA-Exim-Mail-From: tony@tndh.net X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on express.tndh.net X-Spam-Level: X-Spam-Status: No, score=-4.2 required=4.5 tests=ALL_TRUSTED,RP_MATCHES_RCVD autolearn=unavailable version=3.3.1 Subject: RE: BBB uarts & pps dts definitions X-SA-Exim-Version: 4.2 X-SA-Exim-Scanned: Yes (on express.tndh.net) X-BeenThere: freebsd-arm@freebsd.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: "Porting FreeBSD to ARM processors." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 27 Jan 2017 06:28:39 -0000 Ian Lepore wrote: =20 > On Thu, 2017-01-26 at 15:41 -0800, Tony Hain wrote: > > > > > > > > -----Original Message----- > > > From: Ian Lepore [mailto:ian@freebsd.org] > > > Sent: Thursday, January 26, 2017 1:33 PM > > > To: Tony Hain; freebsd-arm@freebsd.org > > > Subject: Re: BBB uarts & pps dts definitions > > > > > > On Thu, 2017-01-26 at 12:53 -0800, Tony Hain wrote: > > > > > > > > Ian Lepore wrote: > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > snip > > > > > > > > > > > > [even more snip] > > That makes some degree of sense based on what I am seeing, though = that > > is a very low input impedance on the BBB. I was expecting ~100k. My > > source is a > > 555 on an ancient ttl/RS232 board I built because the 20 us pulse = from > > the GPS was too fast (between the slew rate of the 3232 and the DCD > > detection window on the com port) to go with a simple level > > conversion. Sounds like it might be best to do an active 3.3v driver = at this > point. > > > > Tony >=20 > BTW, not related to the BB stuff... a while back I added "narrow pulse > capture" support to uart(4) for CTS/DCD PPS capture, you can use it = with > pulses as narrow as 1uS, maybe even less on some hardware. =A0The = tradeoff is > that you can only capture assert edges, not clear. =A0The support goes = back to > 10.3 or so, details are in the uart(4) manpage. I saw references to that and was going to go looking for them again if = the timer pin approach failed. I was not overly hopeful though because it = was not clear to me how that would mesh with using NTPsec which would be expecting a DCD transition. Let's hope the fix in the other note = resolves this so I never have to worry about that. Tony =20