Date: Thu, 19 Apr 2001 21:41:57 +0200 From: Poul-Henning Kamp <phk@critter.freebsd.dk> To: Warner Losh <imp@harmony.village.org> Cc: David Miller <dmiller@sparks.net>, freebsd-hackers@FreeBSD.ORG Subject: Re: [OT] parallel port for IO? Message-ID: <60546.987709317@critter> In-Reply-To: Your message of "Thu, 19 Apr 2001 13:34:17 MDT." <200104191934.f3JJYH806407@harmony.village.org>
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In message <200104191934.f3JJYH806407@harmony.village.org>, Warner Losh writes: >If you have only 1 source, then you can use the ack line of the >parallel port and the ppi driver to get timestamped events. If you >have more than one, then you might be able to wire a simple latch to >the ACK line and sample of to 8 sources. That's trickier as their's >some hair in converting the signals to pulses, worrying about races, >etc. 1 source gives you nanosecond resolution (but only ms accuracy >due to interrupt latencies, us if you hack it to be a fast interrupt). Use the pps driver and you get microsecond jitter with nanosecond resolution. The pps driver implements the RFC2783 PPS-API for timestamping external events. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 phk@FreeBSD.ORG | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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