Re: [CAD_CAM_EDM_DRO] Windows timing subroutines, how do they work?

Hi Jon,

>The jitter in the regularly scheduled interrupts is under 1 uS! And,
>that is an absolute,
>not some statistical average. It NEVER stutters by more than 1 uS,
>EVER, no matter
>how long you sample for.
>
>

Even if doing DMA or heavy accelerated graphics? I find that hard to
believe. The PC's hardware is simply not designed to achieve that sort
of timing resolution.

>I've been running a servo Bridgeport mill since 1998 using EMC under
>real-time Linux,
>and I can tell you with great authority that the timing is not corrupted
>by "clock, comports,
>disk, mouse, display, sound,dma, pci, usb, etc."
>
>

That isn't a fair example. What is your servo cycle time? I would have
thought it would be around 1ms. Even timing jitter of 100us is unlikely
to have a noticeable effect. This is easily achieveable as DMA etc are
unlikely to continue for more then a few tens of us. I bet that EMC also
has jitter problems when running steppers, just like Mach2.

Of course a hardware pulser is the best solution for steppers but it
adds quite a bit to the cost.

Les