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. > > ... > >>> + must be a power of 2. >>> + >>> + * - ``frequency_offset`` >>> + - Hz >>> + - Base FTW to which scaled parallel data is added. Range :math:`[0, >>> f_{SYSCLK}/2)`. >>> + >>> + * - ``phase_offset`` >>> + - rad >>> + - Base phase for polar modulation. Lower 8 bits of POW register. >>> + Range :math:`[0, 2\pi/256)`. >>> + >>> + * - ``scale_offset`` >>> + - fractional >>> + - Base amplitude for polar modulation. Lower 6 bits of ASF register. >>> + Range :math:`[0, 1/256)`. >>> + >> >> I guess there was some discussion on these attributes. I see some of these >> in the >> ad9832 driver in staging, but I'm guessing they are new ABI. It isn't clear >> to >> me from the documentation here what they actually do though. I guess they are >> just basic transformations on the input signal? > > Not sure how the ABI is not clear: > > For a channel that allows amplitude control through buffers, this > represents the value for a base amplitude scale. The actual output > amplitude scale is a result with the sum of this value. > > So yes, it is a basic transformation.
I didn't have time to read the ABI docs yet. For scale_offset though, how is that different from the existing offset attribute? > >> >> 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? > > Zero is a valid value to be written. > >>
