On 06/26, David Lechner wrote: > On 6/25/24 4:55 PM, Marcelo Schmitt wrote: > > Document wiring configurations for the AD4000 series of ADCs. > > > > Signed-off-by: Marcelo Schmitt <marcelo.schmitt@xxxxxxxxxx> > > --- > > Documentation/iio/ad4000.rst | 131 +++++++++++++++++++++++++++++++++++ > > Documentation/iio/index.rst | 1 + > > MAINTAINERS | 1 + ... > > +Wiring connections > > +------------------ > > + > > +Devices of the AD4000 series can be connected to the SPI host controller in a > > +few different modes. > > + > > +CS mode, 3-wire turbo mode > > +^^^^^^^^^^^^^^^^^^^^^^^^^^ > > The datasheet also has the same diagram in _Figure 55. CS Mode, 4-Wire Turbo Mode > Connection Diagram_. So maybe we should call this "register support mode" or > something like that instead of mentioning 3 or 4-wire? > Humm, ADAQ4003 datasheet has the same figure for CS Mode, 4-wire turbo mode and CS mode, 4-wire with busy indicator although other datasheets have MOSI to SDI in 4-wire turbo as you said. The register read/write functionality sections say CNV must be brought low to access the configuration register. I'll leave it as it is for now as I have not tested reg access with CNV high. We can update this in the future if find out reg access to work in 4-wire mode. > > + > > +Datasheet "3-wire" mode is what most resembles standard SPI connection which, > > +for these devices, comprises of connecting the controller CS line to device CNV > > +pin and other SPI lines as usual. This configuration is (misleadingly) called > > +"CS Mode, 3-Wire Turbo Mode" connection in datasheets. > > +NOTE: The datasheet definition of 3-wire mode for the AD4000 series is NOT the > > +same of standard spi-3wire mode. > > +This is the only connection mode that allows configuration register access but > > +it requires the SPI controller to support the ``SPI_MOSI_IDLE_HIGH`` feature. > > + > > +Omit the ``adi,sdi-pin`` property in device tree to select this mode. > > + > > +:: > > + > > + +-------------+ > > + + ----------------------------------| SDO | > > + | | | > > + | +-------------------| CS | > > + | v | | > > + | +--------------------+ | HOST | > > + | | CNV | | | > > + +--->| SDI AD4000 SDO |-------->| SDI | > > + | SCK | | | > > + +--------------------+ | | > > + ^ | | > > + +--------------------| SCLK | > > + +-------------+ > > + > > I think the rest of the explanations are good. >
