Re: [CAD_CAM_EDM_DRO] Re: CNC Pulse jitter?

Patrick Mendiuk wrote:

> Jon,
> What I'm looking for is a step generator and EMC with no glitches.

Well, that is what I'm working on. The hardware is now working, the
diag program works, but I'm having a few small problems with the EMC
makefile system that compiles EMC. I probably will have it in a day or
so.

> > If I can figure out how to make the RT scheduler schedule a task based on
> an interrupt other than the interval
> > timer on the motherboard, then I can rig this to interrupt the CPU.
>
> If you don't have external timer interrupts how are you syncronizing your
> board with EMC during accel/deceleration? Do you have a big fifo on there
> and they run asyncronously?

No, it is totally synchronous. The RT scheduler uses the motherboard
interval timer to schedule the real-time component of EMC to get the
current position and calculate new velocities for the rate generators.
So, 1000 times a second, it does that and the board drives the steppers.
The CPU doesn't tell it to make steps, however, it just tells it to move
at some programmed rate, and the hardware determines exactly when a step
should be issued. Since the CPU is totally unaware of the steps, it has to
know position, so the hardware counts step pulses if no encoders are
present on the motors. I demonstrated a prototype of this at NAMES
last year, and now have it all on one board, essentially all on one chip,
in fact! It works very much like a servo system.

Jon