Re: Adding MAX1363 to BBB

[Michael Welling <mwelling@ieee.org>]

On Mon, Aug 31, 2015 at 05:24:21PM +0100, Jonathan Cameron wrote:
> On 31/08/15 17:01, Greg Wilson-Lindberg wrote:
> >  
> > 
> >> -----Original Message-----
> >> From: Michael Welling [mailto:mwelling79@gmail.com] On Behalf 
> >> Of Michael Welling
> >> Sent: Friday, August 28, 2015 5:32 PM
> >> To: Greg Wilson-Lindberg
> >> Cc: linux-iio@vger.kernel.org
> >> Subject: Re: Adding MAX1363 to BBB
> >>
> >> On Fri, Aug 28, 2015 at 04:56:20PM -0700, Greg Wilson-Lindberg wrote:
> >>>
> >>> I've got the system running, but I get an invalid argument 
> >> error on the call to iio_buffer_refill().  I'm basically 
> >> using the same code as for the tsadc, just added in a fourth 
> >> channel, and none of the setup calls are returning errors, 
> >> but the first iio_buffer_refill() call returns an error.  
> >> I've dumped out the parameter that is being passed to the 
> >> iio_buffer_refill() call and it is the same as the value that 
> >> was returned from the iio_device_create_buffer() call.
> >>>
> >>> I've looked at the libiio source and I don't see anything 
> >> obvious that should return invalid argument for the 
> >> iio_buffer_refill() call.
> >>>
> >>
> >> I believe that you need to register an interrupt for buffered 
> >> access to work.
> >>
> >> Do you have an interrupt connected and registered?
> >>
> > 
> > Nope, no interrupt.  So I guess I would need to ask, how would I register the interrupt in the Device Tree?
> The max1363 (and similar) don't have a dataready interrupt as they
> are clocked of the actual clock cycles of the i2c transfers.  So
> they only read on demand.
>

Ah, yes. Looking at the datasheet the interrupt is triggered by a window
comparator not end of sample.

> > 
> > Or, alternatively, can I just get individual readings through IIO?
> Either via sysfs, or by adding a sysfs trigger and poking that.
> To add a sysfs trigger you'll need to probe the module, then poke
> a number into the add_trigger attribute to create a trigger which can
> then be associated with the max1363 (as normal).
> 
> Then to 'fire' the trigger write to the trigger_now attribute of the
> relevant trigger.
> 
> Ideally Daniel will be back soonish with a final version of the
> high resolution timer trigger that would also work well here.
> (it's rather tied up with some configfs support which wis
> trickier!).

It is probably easiest to sample using sysfs directly.

This would be same as the last method we tried while trying to
access to TI ADC and touchscreen simultaneously.

http://www.spinics.net/lists/linux-iio/msg20577.html

> 
> Jonathan
> >  --
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