Re: [gentoo-embedded] real time linux

[steve]

Have you checked out linux cnc

http://www.linuxcnc.org/

It uses rtlinux to run steppers on cnc mills, etc.  


steve



On Sun, 2005-05-15 at 11:02 -0300, Francisco Ares wrote:
> Justin Cormack wrote:
>
> >
> > On 13 May 2005, at 02:45, Francisco Ares wrote:
> >
> >>
> >> And as far as there are so many possibilities, does anyone know of
> >> some kind of benchmarks between them?  Or should I just try some
> >> different ones for my application? BTW, it is a stepper motor 4
> >> axles control for a starting point, but I would like to bring more
> >> automation out of an existing PLC to a Linux industrial-grade box.
> >>
> >
> > What are the constraints for this application? ie how often do you
> > need to write stuff? I have never looked at this application in
> > detail, inly very roughly. You can write a kernel module that runs on
> > the timer interrupt (max 1000Hz on i386, may vary on other
> > platforms). Doing much more than this is problematic without another
> > source of interrupts. But if you have DA converters that give
> > interrupts on your motor control hardware you could use these, or add
> > a timer chip that gives customisable interrupts.
> >
> > justin
> >
>
> The main constraint is that I have to generate a pulse train at different frequencies as constant as possible, and also be able to vary that frequency during ramp up and down.
>
> My stepper motor driver needs a pulse for each micro step desired at the motor, and also a logic level for direction.
>
> I guess for now that the maximum frequency of these are about 5kHz, but I've got to have 4 (maybe 5) of them, most of the time they will start together, but they will almost always end up in different points, so I will need three ramp and steady frequency generators.
>
> Any advice? Or should I forget trying to use the parallel port for this and go out and buy a motion control ISA board?
>
> Thanks
> Francisco
>
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