Sory I was too lazy to look up the correct number.   So to power down the
Pi, you place a scrip in Run Level 0.  That sends a command over some link
to you power controller to turn off the power to the motors "now" and to
the Pi in about 1 minute.  The power controller does this then goes into a
mode where it monitors the "on" button.    They make low-power processors
that draw just microwatts that would be suitable.

One more thing, the break on the power to the PC could be either the AC
line or the USB-C line.   I'd do the USC so the power controller can be
powered.

On Wed, Feb 16, 2022 at 9:35 AM Mark Wendt <wendt.m...@gmail.com> wrote:

> Runlevel 6 on Unix/Linux systems is a reboot.  Runlevel 0 is a shutdown.
> Using either the init or telinit scripts as superuser will get you to your
> desired runlevel.  Running init 6 as root or superuser will reboot your
> system.  Running init 0 as root or superuser will shut your system down.
> There are other runlevels that do various things, such as runlevel 1 which
> puts the machine in singleuser mode.
>
> Mark
>
> On Wed, Feb 16, 2022 at 12:13 PM Chris Albertson <
> albertson.ch...@gmail.com>
> wrote:
>
> > This is the problem with an instant acting switch.  The pi gets one if
> the
> > GPIO pins low and the replay opens, shutting down power but then the
> power
> > is removed before the OS shuts down potentially corrupting storage.
> >
> > I think the only solution is the solution that every modern electronic
> > device uses. Turing on your using a remote control is the same problem.
> > The TV has to issue a command to the relay that controls power, put how
> to
> > do that if the TV is off?
> >
> > Solution, there is a second power control processor that controls the
> > power.  The "processor" can be a dumb delay timer but today
> > microcontrollers are cheaper than timers and allow you to have functions
> > like sequencing at no extra cost but software. Even cheaper are power
> > management  chips but those are designed for use inside the power supply.
> >
> >
> > You will need to implement somekind of a delay device that is triggered
> by
> > the Pi as it goes into Run Level 6 (I think 6 is "shutdown"?)   The same
> > controller can monitor the power button and when moved from off to on
> start
> > the Pi, wait for it to boot then turn on the CNC motor power.  The Pi
> > wouldtalk to the controller with a GPIO pins or use some serial interface
> > like I2C.   I woulduse whatever serial interface is easy to program on
> the
> > microcontroller.
> >
> > This power controller would tie into e-stop also.  The e-stop that comes
> > from the user interface would send a signal over that interface to drop
> > power to the motors.   Yes the "real" is best but now you can make the
> > software one a little better.
> >
> >
> >
> > On Wed, Feb 16, 2022 at 6:17 AM Thaddeus Waldner <thadw...@gmail.com>
> > wrote:
> >
> > > > Just use a simple 10A relay with 5V coil
> > > > As a latch, you press a button to power up, ie power the coil, then
> the
> > > > same line gets dropped by the Pi to power off..
> > >
> > > How does the pi drop the 5v line after shutting down?
> > >
> > > _______________________________________________
> > > Emc-users mailing list
> > > Emc-users@lists.sourceforge.net
> > > https://lists.sourceforge.net/lists/listinfo/emc-users
> > >
> >
> >
> > --
> >
> > Chris Albertson
> > Redondo Beach, California
> >
> > _______________________________________________
> > Emc-users mailing list
> > Emc-users@lists.sourceforge.net
> > https://lists.sourceforge.net/lists/listinfo/emc-users
> >
>
> _______________________________________________
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>


-- 

Chris Albertson
Redondo Beach, California

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