> You don't need the kernel mode device driver to access the device
> unless you want to squeeze out the fastest possible sampling rate.
> Everything can be done from userspace, using the same access
methods.
> It's a tad slower, that's all.
>
> I believe there are several other example programs using the MAX197
in
> the forum file archive too, or referenced in the forum posts. One
> probably does exactly what you need already....
>
sounds like jj's code is what I need.
...
>
>
> > However, I dont see this in the reference.
> > http://www.embeddedarm.com/downloads/Components/EP9302-PP2.pdf
> >
> > Here I see a straight line tranfer function in fig20 on page 32.
What
> > document are you refering to?
> >
> > Is this example a hangover from an earlier board perhaps?
>
> No, that's the graph I'm referring to. It's a straight line, but
look
> at the digial values: they are not monotonic.
>
> If you replot it as described above you'll see two sections: one has
> xrange (0:61A8) and yrange (vref/2:vref), the second has xrange
> (9E58:FFFF) and yrange (0:vref). I'd try ascii art, but I know
better :)
>
> Regards ...... Charlie
>
Oh what ? A sociologists graph in a data sheet! Pretty deceitfull way
to make a transfer function look linear when in reality it's got a
profile like a factory roof.
This quirk really needs a comment in the example code. Hopefully
Eddie will pick up on that.
I'll bet this has caused a lot of ppl some hours of head scratching
before they realised what the score was.
Many thanks for your help. ;)
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