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* [Xenomai-help] Writing from user space direct to IO Ports without mode switches
@ 2007-07-17 22:23 Renner Johannes
  2007-07-18  6:47 ` Gilles Chanteperdrix
  2007-07-18  8:22 ` [Xenomai-help] Writing from user space direct to IO Ports without mode switches Philippe Gerum
  0 siblings, 2 replies; 9+ messages in thread
From: Renner Johannes @ 2007-07-17 22:23 UTC (permalink / raw)
  To: xenomai

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Hello everyone,

The outb functions to control parallel ports in my user mode RT task causing inacceptable jitter and make the task unstable(-110) at higher(10khz) output frequencies. I believe this is due to mode switches form Primary to the Secondary mode.
I tried to access the ports via /dev/mem and mmap() (method from xenomai/examples/common/hw_direct_io.c) but thus mapping is successful, writing -whatever- to the mapped pointer does not set any IO's on my x86.
I have read that some Xenomai RT testing with the Parallel port at frequencies above 200khz showed excellent results. Which functions are used for such precise timings and are they only available in kernel space?

Thanks in advance 

Johannes

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^ permalink raw reply	[flat|nested] 9+ messages in thread

end of thread, other threads:[~2007-07-20 19:28 UTC | newest]

Thread overview: 9+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2007-07-17 22:23 [Xenomai-help] Writing from user space direct to IO Ports without mode switches Renner Johannes
2007-07-18  6:47 ` Gilles Chanteperdrix
2007-07-18 10:19   ` [Xenomai-help] Writing from user space direct to IO Ports withoutmode switches Renner Johannes
2007-07-18  8:22 ` [Xenomai-help] Writing from user space direct to IO Ports without mode switches Philippe Gerum
2007-07-18 10:12   ` Renner Johannes
2007-07-18 10:47     ` Philippe Gerum
2007-07-19 21:10       ` Vincent Levesque
2007-07-20  7:47         ` Jan Kiszka
2007-07-20 19:28           ` Vincent Levesque

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