On 6/30/22 12:05, Leonardo Marsaglia wrote:
I guess you just convinced me about purchasing a RPi4 and start
experimenting with it :). I would love to use one of those for my next
project or motherboard replacement.
You will find it noticeably slower than the intel stuff we are getting
used to.
1. It will have latencytest figures in the 12 u-second are when it not
doing
anything else. More than good enough to run LinuxCNC.
2. Use until I say different, raspios buster. The python in raspios
bullseye is too new for LinuxCNC.
3. most other activity except for running Firefox won't bother the
machine its running.
Firefox is an IRQ pig, and the machine WILL stutter.
4. if like me, you've a whole passel of hand controls of it, I have a
pair of mpja.com's
$22 100 ppi dial encoder's on the apron, straddling the x motor drive,
one running X jog,
one runs Z jog and back when I was running it with the slower pi3, I
setup a second,
200 Hz "jog thread" and put all the hand stuff in it, in execution order
of course. Based
on the theory that the human hand can't move any faster than that. It
still acts and
feels like realtime to me, but it freed up the servo-thread to get the
real work done on
the pi3b. And I never tried to make it back to a more normal
servo-thread when I
installed a pi4 and booted it from the same armhf based card. If that
interested, I'll
put some more stuff up on my web page. I need to write up a README on
how to install
the kernel I've been using yet, but the tarball can be had from my site
as of a few days ago.
The install is simple but the foundation frowns on unofficial kernels so
I had to invent my
own install procedure using a card reader
5. uptimes are from power outage to power outage, I can't remember the
last time I
actually had to reboot it. I've a small USP on it, and a 20kw standby in
the back yard.
See my Sig for the URL.
[...]
Take care and stay well.
Cheers, Gene Heskett.
--
"There are four boxes to be used in defense of liberty:
soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author, 1940)
If we desire respect for the law, we must first make the law respectable.
- Louis D. Brandeis
Genes Web page <http://geneslinuxbox.net:6309/>
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