On Thu, 18 Jun 2026 14:27:32 +0100 Rodrigo Alencar via B4 Relay <[email protected]> wrote:
> From: Rodrigo Alencar <[email protected]> > > Add documentation for the AD9910 DDS IIO driver, which describes channels, > DDS modes, attributes and ABI usage examples. > > Signed-off-by: Rodrigo Alencar <[email protected]> > --- > Documentation/iio/ad9910.rst | 759 > +++++++++++++++++++++++++++++++++++++++++++ > Documentation/iio/index.rst | 1 + > MAINTAINERS | 1 + > 3 files changed, 761 insertions(+) > > diff --git a/Documentation/iio/ad9910.rst b/Documentation/iio/ad9910.rst > new file mode 100644 > index 000000000000..113521fead3e > --- /dev/null > +Single Tone mode > +---------------- > + > +Single tone is the baseline operating mode. The ``profileY`` channels > +provide enable, frequency, phase and amplitude control: > + > +.. flat-table:: > + :header-rows: 1 > + > + * - Attribute > + - Unit > + - Description > + > + * - ``en`` > + - boolean (0 or 1) > + - Enable/disable profile Y. Only one profile can be active at a > + time. When enabling a profile it disables the current active profile. > + Disabling an active profile brings the device to a powered down state. > + > + * - ``frequency`` > + - Hz > + - Output frequency. Range :math:`[0, f_{SYSCLK}/2)`. Stored in the Probably spaces around the / for consistency. > + profile's frequency tuning word (FTW). > + > + * - ``phase`` > + - rad > + - Phase offset. Range :math:`[0, 2\pi)`. Stored in the profile's phase > + offset word (POW). > + > + * - ``raw`` > + - integer > + - Amplitude scale factor code. Range :math:`[0, 16383]`. Stored in the > + profile's amplitude scale factor (ASF) register. The physical output > + amplitude is ``raw * scale`` where ``scale`` is read from the ``phy`` > + channel. ... > +Digital ramp generator (DRG) > +---------------------------- > + > +The DRG produces linear frequency, phase or amplitude sweeps using dedicated > +hardware. The active ramp target (destination) is selected by enabling the > +corresponding typed channel at channel number 130: > + > +- ``out_frequency130`` (label ``drg_frequency``) — ramp targets frequency > +- ``out_phase130`` (label ``drg_phase``) — ramp targets phase > +- ``out_altcurrent130`` (label ``drg_amplitude``) — ramp targets amplitude > + > +Writing ``en=1`` to one of these channels enables the DRG and switches its > +destination. Writing ``en=0`` disables the DRG if the channel is the current > +active destination; writing to an already-inactive destination is a no-op. > + > +Each destination channel also exposes a read-only ``scale`` attribute > +reporting the physical quantity per ramp register LSB, which allows > converting > +raw limit codes to physical values. > + > +The two ramp channels ``out_altcurrent131`` (``drg_rising``) and > +``out_altcurrent132`` (``drg_falling``) configure ascending and descending > +ramp parameters independently. > + > +Destination channel attributes > +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ > + > +.. flat-table:: > + :header-rows: 1 > + > + * - Attribute > + - Unit > + - Description > + > + * - ``en`` > + - boolean > + - Enable the DRG with this channel as the active destination. Only one > + destination can be active at a time. > + > + * - ``scale`` > + - Hz/LSB, rad/LSB or mA/LSB > + - Read-only. Physical quantity per raw units. Multiply a ramp > + rising/falling channel ``raw`` value by this scale to get the physical > + ramp target. > + > +Ramp channel attributes > +^^^^^^^^^^^^^^^^^^^^^^^ > + > +.. flat-table:: > + :header-rows: 1 > + > + * - Attribute > + - Unit > + - Description > + > + * - ``dwell_en`` > + - boolean > + - Enable dwell at the ramp limit. When disabled, the ramp > + auto-transitions at this limit without waiting for the DRCTL pin. > + Disabling both creates a bidirectional continuous ramp (triangular > + pattern). Other combinations create single-shot ramps at the DRCTL > + pin transition. > + > + * - ``raw`` > + - integer (64-bit) > + - Ramp limit expressed as a raw DRG register code in > + :math:`[0, 2^{32}-1]`. The physical value is ``raw * scale`` where > + ``scale`` is read from the active destination channel. > + > + * - ``sampling_frequency`` > + - Hz > + - Ramp clock rate. Controlled by an integer divider; the written value > + is adjusted to the nearest supported rate. > + > + * - ``raw_roc`` > + - /s > + - Rate of change. Number of register codes advanced per second, computed > + from the hardware step size and the current ramp clock. Writing > + requires ``sampling_frequency`` to be configured first. > + > +Usage examples > +^^^^^^^^^^^^^^ > + > +Configure a frequency sweep from 40 MHz to 60 MHz with a rate of change of > +25 GHz/s: > + > +.. code-block:: bash > + > + # Disable dwell on both limits for a bidirectional continuous ramp > + echo 0 > /sys/bus/iio/devices/iio\:device0/out_altcurrent131_dwell_en > + echo 0 > /sys/bus/iio/devices/iio\:device0/out_altcurrent132_dwell_en > + > + # Set ramp rate at 250 MHz > + echo 250000000 > > /sys/bus/iio/devices/iio\:device0/out_altcurrent131_sampling_frequency > + echo 250000000 > > /sys/bus/iio/devices/iio\:device0/out_altcurrent132_sampling_frequency > + > + # read the frequency scale to convert physical values to raw units > + cat /sys/bus/iio/devices/iio\:device0/out_frequency130_scale > + 0.232830643650 > + > + # 40 MHz / 0.232830643650 = 171798692 > + echo 171798692 > /sys/bus/iio/devices/iio\:device0/out_altcurrent131_raw > + # 60 MHz / 0.232830643650 = 257698038 > + echo 257698038 > /sys/bus/iio/devices/iio\:device0/out_altcurrent132_raw Why is this writing frequencies to altcurrent channels? Shouldn't this be the frequency ones? > + > + # 25 GHz/s / 0.232830643650 = 107374182402 > + echo 107374182402 > > /sys/bus/iio/devices/iio\:device0/out_altcurrent131_raw_roc > + echo 107374182402 > > /sys/bus/iio/devices/iio\:device0/out_altcurrent132_raw_roc > + > + # Enable the DRG with frequency as the destination > + echo 1 > /sys/bus/iio/devices/iio\:device0/out_frequency130_en > + > +RAM mode > +-------- ... > + > +.. code-block:: bash > + > + echo 1 > /sys/bus/iio/devices/iio\:device0/out_altcurrent100_powerdown > \ No newline at end of file Tidy that up. Thanks, Jonathan
