Date: Mon, 1 Oct 2001 11:44:59 -0700 (PDT) From: Julian Elischer <julian@elischer.org> To: Warner Losh <imp@harmony.village.org> Cc: Bart Kus <bsd@shell-server.com>, hackers@FreeBSD.ORG Subject: Re: precise timing Message-ID: <Pine.BSF.4.21.0110011142340.86630-100000@InterJet.elischer.org> In-Reply-To: <200110010335.f913Z6701389@harmony.village.org>
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the REALLY best answer was the suggestion to use teh speaker output.. (ANDED with anuother bit.. you don;t want the bios BEEP to move teh drill.. alrternatively you can also use the tiemrs.. remember that the pcaudio device runs the available clock chip up to 16,000 Hz.. and changes teh duty cycle on each cycle.. You could do something like that.... julian On Sun, 30 Sep 2001, Warner Losh wrote: > In message <200109301010.07784@EO> Bart Kus writes: > : Right now, I use for() as a timing loop. I calibrate it on program start > : and can then get very precise timing. There are, of course, the intermittent > : interruptions of the multitasker. So this solution is not ideal by any > : means. In fact, the for() loop approach is really meant for the DOS port of > : this software. I'm wondering if there is any way I can access a more precise > : interrupt-driven (or blocking) timing source. I know I can do a select() > : with supposedly microsecond accuracy, but I doubt that it is in fact that > : accurate in practice (doesn't the kernel only use a 100Hz clock or > : something?). Is there any way to get at the system timers on the > : motherboard? Those can provide precise timing, no? > > you are likely better off implementing this as a device driver, likely > with the parallel port bus stuff. > > Warner > > To Unsubscribe: send mail to majordomo@FreeBSD.org > with "unsubscribe freebsd-hackers" in the body of the message > To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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