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Re: [rtl] Stability Problems while generating 1KHz signals
I think you might want to hook a purely periodic task up to the RTC.
That's easy to do -- there's an example in rtl/examples/parallel/rtc_toggle.c
Otherwise:
1. Wait for the RTLinux with pure periodic tasks
2. Wait for the RTLinux with 8 bit clock operations
3. Implement 1 or 2 above
4. Use Paolo's version of rtlinux
5. Get a better motherboard!
6. Wait for the coming APIC timer Rtlinux version that will
work on some newer up and all smp motherboards.
7. see (3)
I'm very disatisfied with the current timing code, Michael had something
better in V7, but (1) and (2) are priorities. I hope to get to them
next week.
On Thu, Oct 08, 1998 at 11:37:00PM -0600, Hermann Lauer wrote:
> Hello List Readers,
>
> I dug into the RTlinux code meanwhile and maybe I now understand the most
> relevant parts of the code (Is there a programming sheet of the 8254/8253
> available on the net somewhere and a schematics of the wiring of the counters
> ?).
>
> I defined the debug code in RTlinux0.9 9F (which measures the ticks while
> setting a new counter value?) and come up with the following numbers:
>
> 66 MHz pentium: new record: 02 31b
> 166 MHz pentium: new record: 0a 0c
> 66 MHz 486: new record: 13 48
>
> So the 66 pentium is very bad - it seems to take somtimes more than a half
> period of decimal 500 to set the counter 0 !
>
> The chips on the 66 MHz pentiums motherboard are: S82433/4LX (3 chips) and
> S82378ZB
>
> So I should just give up with that motherboard - or what do you think ?
>
> Thanks for any further ideas/suggestions/help.
>
> Greetings
>
> Hermann
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--
---------------------------------
Victor Yodaiken
Department of Computer Science
New Mexico Institute of Mining and Technology
Socorro NM 87801
Homepage http://www.cs.nmt.edu/~yodaiken
PowerPC Linux page http://linuxppc.cs.nmt.edu
Real-Time Page http://rtlinux.org
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