On 9/8/23 08:54, andy pugh wrote:
On Fri, 8 Sept 2023 at 12:30, gene heskett <ghesk...@shentel.net> wrote:
The problem is the analog i/o sample_hold, I need the digital equ so I
don't have to do a jillion S32-float conversions.
I don't know why sample-hold is only S32, it would be much more useful
if it was configurable.
However, you can fake a sample-hold with a mux (this is something that
I have done several times)
So have I but had forgotten it. Sadly I've reached that age where I have
forgotten what, if anything I had for breakfast.
I can also use that to block the error inputs from the stepper/servo
controllers on the sixty40 mill which don't cancel that signal until
fully functional at powerup. Set a timer to hold the error from getting
to the e-stop for 100 milliseconds at powerup. Powerup to the machine
and possibly its lighting is controlled by the F2 state on most of my
machines, F2 off, machine is cold. Which is what those drivers need to
re-enable after they've errored. Well tested on the Sheldon and its pi,
did the same on the sixty40 but neither machine has ever faulted running
gcode. They also use the error as a current modulator banging the motor
with everything the psu has for about 2 miliseconds, if that fails, the
shut the motor off and issue the alarm, stopping linuxcnc in its tracks
with no broken tools, but run them at very low currants if moving
easily. And all 4 of them run cold unless that 3NM as B on the sixty40,
a twin of this one is spinning the chuck at more than 200 rpms, runs
around 350 for a couple hours making that vice screw. Its spinning the
motor 5x the chucks rpms. Warms it up a bit.
If you feed the output of a mux back to the input-1 and the value to
be sampled to input-0, then you have a sample-hold.
Thank you Andy. That is exactly what I need.
mux_generic can be configured for any datatype (and even to convert
between datatypes, but that won't work if it's configured for
sample_hold as the output feeds back to the input so needs to be the
same datatype.
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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