Re: [Gumstix-users] Re: Kernel programming example help

[Nik M. <add...@gm...>]

This may end up as a double post on the archives, due to sending from
the wrong email account.

On 3/9/06, Nik Martin <nm...@ra...> wrote:
> On 3/9/06, Dave Hylands <dhy...@gm...> wrote:
> > Hi Nik,
> >
> > On 3/9/06, Nik Martin <add...@gm...> wrote:
> > > My problem was the KERNELDIR version !=3D 2.6.15
> > > Nik
> > >
> > > Also, It's building the proper dir in /proc, but not in /dev.  adding
> > > debug statements now to try to figure out why
> >
> > You need to manually create the entry in /dev (that's the udev support
> > stuff I was talking about). If you want to make the changes yourself,
> > then take a look at the differences between the latest and previous
> > versions of robostix_drv.c:
> >

 I just re-read and noticed the /udev reference.  I'm new to kernel hacking=
.

>
> > <http://websvn.gumstix.com/diff.php?repname=3DBuildroot&path=3D%2Fbranc=
hes%2Fprojects%2Frobostix%2Fgumstix%2Frobostix_drv.c&rev=3D0&sc=3D0>
> >
> > If memory serves me correctly, the name passed into
> > class_device_create will be the name of the /dev entry created.
> >
> > > Also, since the main app is still just looping looking for events, I'=
m
> > > not sure what I'm gaining in regards to performance.  I'm assured to
> > > not miss an event but the event will be caught at the speed of the
> > > main loop.  I need to a fairly responsive 5 button keypad UI, so I
> > > need to figure out how to fire software interrupts in the main app
> > > based on interrups in the char driver, to eliminate a time critical
> > > main loop.
> >
> > The main app should just be issuing a non-blocking read call. The read
> > will return when a button is pressed. If you need to do other stuff as
> > well, then launch a thread which does the blocking and have it signal
> > the main thread.
> >
> > It's also possible to implement support for the select call, but that
> > isn't currently in the sample driver (although it's pretty easy to
> > add).
> >
> > What all does you app do?
>
 I have to read a flow meter which outputs a square wave whose
 frequency is relative to the rate of flow.  It's pretty slow, like
 28-30 Hz, but the accuracy is important.  This just needs to happen in
 the background, and I reference the reading  every few seconds to do
 some calculations.  The other IO is a just a set of buttons that act
 as a keyboard to an ncurses UI we're writing for those 2.7" sony LCD's
 from Goldmine Electronics and Earth LCD. Another process ( or maybe
 just a thread in my main app)  will be running a neural network,
 training on the data the main app is collecting, and outputting a set
 of predictive control statements that will be controlling varion loads
 in a home.  Its a DOE funded project, but I'm hoping to get some
 commercial appeal out of the nifty board we're building to support the
 project with.

>
> Nik
>
> >
> > --
> > Dave Hylands
> > Vancouver, BC, Canada
> > http://www.DaveHylands.com/
> >
> >
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