--- In Jim Jackson <> wrote:
>
>
>
>
> On Wed, 10 Oct 2007, j.chitte wrote:
>
> > Hi,
> >
> > I have been talking to a engineer friend about my tests with the
7250
> > + Max193 and it has got him interested. He has a specific need
for
>
> I'm assuming thats a typo and you mean the MAX197 ADC chip.
>
> > some fairly fast ADC and was asking what the max sample rate was.
> >
> > Since my use is very low data rate I was not able to give a full
> > answer but figures I'd seen were not too fast so I wondered if
> > someone who has experience could give an accurate idea of what
can be
> > attained.
> >
> > I'd like to know max sample rate assuming no other major tasks
> > running other than system requirements for the following.
>
> Using Phillip McCarley's ADC kernel module (on the files page of
this
> group) you can get 8000 samples per sec. without anything special
- other
> than an otherwise unloaded machine. Dunno what the jitter on the
samples
> would be like, it uses a spare timer in the CPU to generate timed
> interrupts for doing the sampling.
>
> >
> >
> > Std kernel + adc kernel driver; 2.4 + realtime layer; 2.6 kernel.
> >
> > any other info that seems relevant would be most welcome also.
> >
> > regards,
> >
> > /js
> >
> >
> >
> >
> >
>
thanks for the replies.
I built Phils driver and it compiled without any messing. I compiled
it native after setting the Makefile to use local gcc etc.
insmod adc.o was clean although debug option did not spew the
additional info I understood it should.
the devices apeared and setting sample rate to 4/s through /proc was
fine. However the actual data did not seem to bear much ralaton to
the ADC pins.
:input# cat /dev/adc3
123
123
122
123
123
123
123
123
123
124
123
124
124
:input# cat /dev/adc4
377
266
266
266
266
266
266
266
266
265
266
266
266
:input# cat /dev/adc1
526
528
528
529
528
528
528
528
528
528
the voltages present were : 1.29, 0.0, 0.71 in the same order.
I rebuilt using 5V and UNIPOLAR then rmmod and insmod but then all
but channel-1 gave zero.
since it all went so cleanly I suspect I may have misunderstood how
it is suppossed to work.
Can someone put me straight?
Thanks to Phil for the code.
TIA.
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