On 26/05/11 10:23AM, David Lechner wrote: > On 5/11/26 10:02 AM, Rodrigo Alencar wrote: > > On 26/05/11 09:46AM, David Lechner wrote: > >> On 5/10/26 4:30 AM, Rodrigo Alencar wrote: > >>> On 26/05/09 06:42PM, David Lechner wrote: > >>>> On 5/8/26 12:00 PM, Rodrigo Alencar via B4 Relay wrote: > >>>>> From: Rodrigo Alencar <[email protected]> > >>>>> > >>>>> Add documentation for the AD9910 DDS IIO driver, which describes > >>>>> channels, > >>>>> DDS modes, attributes and ABI usage examples.
... > >>>> And a practical note, they should be "frequencyscale". I don't like that > >>>> it is > >>>> harder to read, but it is easier for a machine to parse. > >>> > >>> Parsers like the ones in libiio is not having problems with that. > >>> > >>>>> +Usage examples > >>>>> +^^^^^^^^^^^^^^ > >>>>> + > >>>>> +Set parallel port frequency modulation with a scale of 16 and a 50 MHz > >>>>> +offset: > >>>>> + > >>>>> +.. code-block:: bash > >>>>> + > >>>>> + echo 16 > > >>>>> /sys/bus/iio/devices/iio:device0/out_altvoltage113_frequency_scale > >>>>> + echo 50000000 > > >>>>> /sys/bus/iio/devices/iio:device0/out_altvoltage113_frequency_offset > >>>>> + > >>>>> +Digital ramp generator (DRG) > >>>>> +---------------------------- > >>>>> + > >>>>> +The DRG produces linear frequency, phase or amplitude sweeps using > >>>>> dedicated > >>>>> +hardware. It is controlled through three channels: a parent control > >>>>> channel > >>>>> +(``digital_ramp_generator``) and two child ramp channels > >>>>> +(``digital_ramp_up``, ``digital_ramp_down``). DRG destination is set > >>>>> when > >>>>> +ramp attributes are written, i.e. writing to ``frequency`` or > >>>>> ``frequency_roc`` > >>>>> +sets the destination to frequency. > >>>> > >>>> Would it be better to say that the destination is set when the the > >>>> value is non-zero? Otherwise, how would one change the destination > >>>> once set? > >>> > >>> Destination is only one, so you just need to write phase or phase_roc, if > >>> you want > >>> to target phase then. Does that not sound intuitive? > >> > >> I was thinking about if you needed to change the configuration. > >> If you set it to phase, then want to change it to frequency, how > >> could you do that if 0 is a valid value for phase? > >> > >> Also how could you know which is selected by reading back the > >> values if 0 is a valid value? > > > > This is where Jonathan raised some concerns, so it is a good oportunity for > > you > > to provide your inputs! Right now, I am returning -EBUSY on read of an > > attribute > > where its destination is not selected. As pointed out, the destination > > selection > > is happening when writting to the attribute. In the previous patch, Jonathan > > suggested frequency_active, phase_active and scale_active to track mode > > priority, > > and It could be leveraged here for DRG destination selection. I havent gone > > for > > that because I was not willing to add that to all the channels given that > > it is > > mostly used for debugging, so I added frequency_source, phase_source and > > amplitude_source to debugfs instead. > > The "last write wins" with the others changing to EBUSY makes more sense to > me now. If the docs said that, I missed it. Otherwise, that would be a helpful > thing to add to the docs here. > > > > > Destination selection for RAM mode is firmware based at this point. > > Seems reasonable. > > > Destination selection for Parallel mode is still not clear... could use > > those *_active attributes or separate channels. > > Since there are _offset attributes proposed for parallel input already, > could we just make it the same where you have to write one of those > attributes? Different from the DRG, both RAM and Parallel mode has this extra polar destination, which targets both amplitude and phase at the same time. For parallel mode I have the attributes: - frequency_scale: applied when destination is frequency - frequency_offset: applied when destination is frequency - scale_offset: applied when destination is polar - phase_offset: applied when destination is polar In parallel mode, there aren't knobs like those for amplitude and phase destinations. With the *_active thing or similar, polar can be both phase_active and scale_active enabled at the same time. However, this would not behave the same way Jonathan suggested, i.e. to be used for mode priority indication... it would be used for destination configuration instead. > > > > >>> > >>> Zero is a valid value to be written. > >>> > >>>> > > > -- Kind regards, Rodrigo Alencar
