Re: [PATCH] staging: iio: dds: ad9834: Enable driver support for AD9833 and AD9834 DDS devices

[Jonathan Cameron <jic23@cam.ac.uk>]

On 11/30/10 16:44, Hennerich, Michael wrote:
>> Jonathan Cameron wrote on 2010-11-30:
>>>> From a generalization point of view we don't care that the square wave
>>>> is a random bonus option the part happens to be able to kick out.
>>>> Ideally we want a naming scheme that makes it's relationship to the
>>>> other waveforms apparent though and it's not entirely obvious how to
>>>> handle that (e.g. how to handle the double frequency square wave this
>>>> part can produce). Things will get more fun if parts have multiple
>>>> outputs tied to one dds channel.
>>>
>>> Actually that's the case here on the AD9834. The signbit is an
>>> independent output. It therefore can't be handled with the
>> dds0_wavetype file.
>> Then have dds0_wavetype0 (sine triangle) and dds0_wavetype1 (square).
>> Document that the second index is only required if there are multiple
>> physical outputs from a given channel.
> 
> How to disable dds0_wavetype1 (square)?
> 
> (square off)?
Nope, it's just like the other output in that it can be disabled so give
it it's own disable attribute.  The naming currently proposed looks a little
strange for this... hmm.  Perhaps change to dds0_out1_wavetype etc for the
other elements.
dds0_out_disable (for both) and dds0_out1_disable allows this channel to be
separately disabled.
> 
> Not all combinations of dds0_wavetype0 (sine triangle) are allowed with the signbit output.
That's fine.  You have dds0_out1_wavtype_available and dds0_out0_wavetype_available
to say what is possible for each of the two outputs of dds0.  
> 
> 
>>> It can be enabled/disabled while the DDS generates a sine wave on the
>>> main output.
>>>
>>> On the AD9833 the signbit square wave feature is routed to the DDS
>> main output.
>> Then that part just has the dds0_wavetype (triangle sine square) as
>> suggested above.
> 
> That's how I implemented it for the AD9833
Excellent, I had missed that.
> 
> Greetings,
> Michael
> 
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