To generate a 120kHz stable square wave at an i/o port you need dedicated
hardware. With current PC hardware you can't do this in software because of
interrupt processing delays. The period of around 8 microseconds is less than
the typical maximum interrupt latency, and every interrupt occurring during
handler execution will extend handler execution time. These delays are very
hardware architecture dependent.
A solution is to use an i/o board with an 8254 or similar timer, configured so
the timer directly controls an output bit. A PLD-based board like the one I'm
developing would do this easily too.
John
On Sat, 11 Mar 2000, dding wrote:
>I want to generate squares from parallel in the highest frequency and
>stable needed. pthread_create() and pthread_make_periodic_np() only give me
>the stable square wave about 30k HZ . I need 120k HZ or more.
>
> I think I can use rtl_request_irq() to register a timer handler and use
>rtl_hard_enable_irq() to enable it! but I don't know how to do it in detail
>! Who can help me ? Thanks a lot!
>
>
> dding
>
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--
John Storrs, Laboratory for Micro Enterprise
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