Mario Sangalli schrieb:
> Il 25/08/2014 15:54, Radoslaw Kudaj ha scritto:
>> Hi,
>>
>> I need to generate microseconds sleep (in microseconds resolution) on QNX 6.6.0.
>> As time tick on the QNX system is 1 ms functions: "clock_nanosleep()" and
>> "nanosleep()" do not provide microseconds sleep accuracy.
>> Is there any other reliable method to sleep over such short period of time (other than nanospin() function which 
consumes too much CPU)?
>>
>> thank you for any help,
>> regards
> A reliable usleep may dependes by platform/CPU  You are using and if
> You can allows or not a preemption during usleep .
>
> If Your system has an hardware timer available , you can use it to 
> generate an
> interrupt for You and do works in ISR or just send a pulse to an 
> interrupt thread.
> Or You can read the timer in a loop and exit after the desidered us are 
> elapsed
Mario wrote: 

"other than nanospin() function which consumes too much CPU)".

that means polling of a timer could not be a solution.

My proposal:

if your target system is x86 based go with the IRQ 8 (RTC) ... it should be available again with QNX 6.6.
If you are working with an non-x86 SoC, then have a look to its hardware resources for hardware timers.

Regards

--Armin

> (be sure to set Your thread priority in order to gain the desidered 
> accuracy).
>
> M.
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+-1 usec would be the best but +-5usec is also acceptable.
One good solution is using HW timer and interrupt, like mario described above, 
but I wonder whether there is another way.

thank you,
Radek