Thanks! I'll look into it.
--- In Jim Jackson <> wrote:
>
>
>
>
> On Mon, 19 Jul 2010, Simon wrote:
>
> > Thanks WouterS and Jim Jackson. Now I understand a little better what's
> > going on in there.
> >
> > My problem is that I'm trying to do some very fast communications through
> > the SPI port and I need to do some flag management through the DIO ports.
> > I've done some tests and when I go beyond 8 kHZ it seems that the kernel
> > gets in the way and creates small delays in the process.
>
> The kernel is getting in the way, but not in the way you seem to think.
> Once mmap has given you an address, then when you use that address you are
> speaking direct to the hardware! But, you are in user space, the kernel can
> stop your process and let something else run at any time.
>
> If you need more guarantees about timing etc go with the suggestions of
> writing a kernel driver. There is a kernel driver for doing i2c on the
> DIO pins on a ts72xx at
>
> http://bioacoustics.cse.unsw.edu.au/archives/html/ts-7000/2006-07/msg00043.html
> and
> http://tisnix.dommel.be/ts-7260/
>
> It might provide some useful reading and be an example for you.
>
> >
> > I was trying to get past that by communicating straight to the hardware.
> > I've read about something called 'nice' to increase the priority of my
> > program but I don't know how to use it for the TS boards. Can someone
> > point me to documentation or tell me how it's done?
> >
> > Thank you very much for your help!
> >
> > --- In Jim Jackson <jj@> wrote:
> >>
> >>
> >>
> >>
> >> On Thu, 15 Jul 2010, Simon wrote:
> >>
> >>> Hi, I've been using the peekpoke instructions as inline assembly and they
> >>> work perfectly. However, I was wondering if there's a way, using inline
> >>> assembly, to use these functions without mmap'ing. Maybe set some flags
> >>> that'd let me control the memory locations directly?
> >>>
> >>> I just want to be able to communicate with the GPIO ports directly
> >>> instead of having to go through virtual memory mapping. Is there a way to
> >>> do this?
> >>
> >> Not without having to go through virtual memory mapping.
> >> You can do it without using peekpoke functions.
> >> Once you have addresses mmap'ed, or addresses calculated from mmap'ed base
> >> addresses, you can use them directly. There is example code around.
> >> If stuck check out the ts7200.c file in any of my programs.
> >>
> >>
> >> cheers
> >> Jim
> >> ----------------------------------------------------------------------------
> >> HomePage: http://www.comp.leeds.ac.uk/jj
> >> TS7200 Page: http://www.comp.leeds.ac.uk/jj/linux/arm-sbc.html
> >>
> >
> >
> >
>
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