> From: [email protected]
> Date: Wed, 3 Feb 2016 23:24:39 +0000
> To: [email protected]
> Subject: Re: [Emc-developers] Prempt RT on Raspi/ARM
> I think you can argue that an ordinary PC as a GUI which reads G-code
> and sends the motion commands to a separate motion controller is a
> sensible and rational architecture.
> After all, this seems to be the common Mach3 setup (Windows and a USB
> smoothstepper) and Mach4 is going even more strongly that way.
>
> I am not sure it makes sense to modify LinuxCNC to work that way. It's
> a fundamentally different system architecture and probably ought to be
> a fundamentally different application.
>
This is the point that many seem to miss. Linuxcnc as a project is to be
a machine controller, not a GUI and infrastructure to feed a machine controller.
There is a very compelling reason this is a good idea: capability added to
the motion controller is available to all hardware combinations.
There are disadvantages to this: realtime does not work well with some
interface protocols (eg. USB)
We in fact do use hardware to make things better - just as the lowest level
possible. Build a micro controller that reads encoders and outputs PWM
and that is a good fit for linuxcnc and they are very good at that.
But build a motion controller in a FPGA or micro controller and now you
have _really_ tied capabilities to specific hardware.
At the moment I don't see the demand for higher performance then
what we have with FPGA hardware help.
Now if you wanted to separate the GUI code from realtime, I guess that
is not a bad thing - it just seems that what you really want is small hardware
that has good video capability - The BBB accelerated graphics are not
available AIUI. The BBB with a FPGA and good graphics would be a great
piece of compact hardware that doesn't break our project idea.
Of course I mostly look from a big machine control side - if you are wanting
to operate something else I can see wanting to use a tablet or phone and
in this case the GUI being separate would be very helpful.
But that still doesn't mean putting the motion controller inside a
microcontroller.
But If you did want to do this, I don't think it would be impossible.
The motion controller is loaded in the HAL files so something else could
be but I bet there is lots of assumption so it would need work to do.
In all I don't see the motivation for putting the motion controller anywhere
but were it is - unless coding motion controllers in micro controllers is
something
you just like to do. (which certainly is not a bad thing)
Chris M
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