> Even th D-525-MW motherboard? I can latency-test for an hour or 2 on this
> machine I'm building up right now, and not show any worse than 5.1
> microseconds for base thread latency, and If I run without that thread,
> which I don't use anyway, and the worst case latency is 4850ns.  Thats
> right alongside the figures I've seen quoted for the STM-32.

I think we might be looking at different numbers.    The interrupt latancy
on the uP
is  12 to 17 cycles depending on the chip.    Let's assume we run at
100MHz, so
a cycle 10ns.  so that is 120 to 170ns.    But I doubt this is what the tool
you are using measures.     I think it measure maximum uncertainly
or "jitter" of a loop period.     So what it really measures is the time
where the
OS has interrupts disabled.

If you were to run a thread on a timmer-based interrupt on the uP with
no OS loaded the "jitter" would be effectily zero,  Some picoseconds I'd
But any OS needs to disable interrupts to access shared memmory or maybe
for some IO drivers.

But if writing motion control on a uP you would not use software to make
so the jitter in the loop is not jitter in the pulses.   the uP (unlike the
Intel x86)
has a"ton" on external, programmable hardware so you can make pulses using
that hardware and have near perfect hardware generated waveforms

Windows security can be "bullet proof". Someone who is very concerned about
someone hacking their CNC miling machine could run their Windows 10
Machine on LAN that is firewalled or even "air gapped" from the Internet.
they could run Windows in a VM. Or they could run Linux or MacOS. or IOS.

> > There is nothing special about Linux other than it provided a cheap
> > and easy to get RT OS.
> And security. Windows may be improving, but connected directly to the
> net, how long before its owned. I went from amiga to linux in 1998, and
> have not been touched since. That of course includes using another linux
> product, dd-wrt, between my local network, and the network at large on
> the other side of my cable modem.

Chris Albertson
Redondo Beach, California

Emc-users mailing list

Reply via email to