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Re: [ts-7000] Re: ts11 Time resolution

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Subject: Re: [ts-7000] Re: ts11 Time resolution
From: Jim Jackson <>
Date: Mon, 17 Sep 2007 22:30:25 +0100 (BST)
On Mon, 17 Sep 2007, fabianmejia wrote:

> Hi All,
>
> Thanks for your answers.
>
> I already checked the manpages for patch, but no really helpful. I
> found a message saying that this patch doesn't work. Also, thanks to
> Jim now I know that patch is not useful for my purposes.
>
> Swiming in the dark waters of linux, and according to your
> suggestions I found the following possible solutions
>
> 1. Using an RTAI: Isn't this too much to get a higher resolution
> timer?
>
> 2. Changing the HZ in kernel. That is, modifying the asm-arm/param.h
> file. And recompiling and installing Kernel (Right?)
> I've never done this before, but reading I got these raw steps:
> download kernel, make, make modules, make modules_install, make
> install (Am I in the right path)?

I am guessing you've never built a kernel.

> 3. Creating a Timer interrupt: Create it the same way as it's built
> in the ADC Kernel driver. Can I run that in user space(The interrupt)?

No you can't run interrupts in user space.
Just use the ADC kernel module. It's a simple interface and I found it
easy to build. You have to configure a kernel src tree first.

>
> I appreciate if you can give me suggestions on which option is better
> for my purposes. (And which one can be accomplished faster)
>
>
> --- In  "j.chitte" <> wrote:
> >
> > --- In  "fabianmejia" <fabianmejia@>
> > wrote:
> > >
> > > Hi All,
> > >
> > > I am under development of a capture system. I need to sample about
> > > 200Hz. That is, about sampling each 0.005 seconds.
> > >
> > > I have it working using the Jim Jackson's adc_logger.
> > >
> > > Unfortunatelly, this can't accomplish the job as it's accurate
> > about 10ms.
> > >
> > > So, I decided using gettimeofday. Oh surprise!!! It doesn't work
> > > properly. microsecond precision? Forget about it. Readings give me
> > > mumbers like this:
> > >
> > > 510000
> > > 530000
> > > 550000
> > >
> > > It sounds like 10msec precision.
> > >
> > > Next step, checking the TS7000 group. I downloaded the file:
> > > linux24_ts8-lck1-cpufreq-230705.patch.gz
> > >
> > > I have a ts11 version. Will this work?
> > >
> > > A noob question: How to have this working? I suppose using the
> > "patch"
> > > command. I ran "patch -p0 lin.......". By the time I am writing
> > this,
> > > the command is still running without showing any message.
> > >
> > > If this command finishes, what will be the outcome? Having the
> > > "gettimeofday" working properly?
> > >
> > > Can I get cpu ticks or something like that in order to have the
> > real
> > > microsecond precision?
> > >
> > > Regards.
> > >
> >
> > I recommend you read `man patch` for the use of patch command.
> >
> > You may want to look at realtime linux refered to in the TS doc if
> > you need faster more accurate timing.
> >
> > /js
> >
>
>
>


 
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