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diff --git a/Documentation/iio/ad4000.rst b/Documentation/iio/ad4000.rst new file mode 100644 index 000000000000..de8fd3ae6e62 --- /dev/null +++ b/Documentation/iio/ad4000.rst @@ -0,0 +1,131 @@ +.. SPDX-License-Identifier: GPL-2.0-only + +============= +AD4000 driver +============= + +Device driver for Analog Devices Inc. AD4000 series of ADCs. + +Supported devices +================= + +* `AD4000 <https://www.analog.com/AD4000>`_ +* `AD4001 <https://www.analog.com/AD4001>`_ +* `AD4002 <https://www.analog.com/AD4002>`_ +* `AD4003 <https://www.analog.com/AD4003>`_ +* `AD4004 <https://www.analog.com/AD4004>`_ +* `AD4005 <https://www.analog.com/AD4005>`_ +* `AD4006 <https://www.analog.com/AD4006>`_ +* `AD4007 <https://www.analog.com/AD4007>`_ +* `AD4008 <https://www.analog.com/AD4008>`_ +* `AD4010 <https://www.analog.com/AD4010>`_ +* `AD4011 <https://www.analog.com/AD4011>`_ +* `AD4020 <https://www.analog.com/AD4020>`_ +* `AD4021 <https://www.analog.com/AD4021>`_ +* `AD4022 <https://www.analog.com/AD4022>`_ +* `ADAQ4001 <https://www.analog.com/ADAQ4001>`_ +* `ADAQ4003 <https://www.analog.com/ADAQ4003>`_ + +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 +^^^^^^^^^^^^^^^^^^^^^^^^^^ + +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 | + +-------------+ + +CS mode, 3-wire, without busy indicator +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +Another wiring configuration supported as "3-wire" mode has the SDI pin +hard-wired to digital input/output interface supply (VIO). In this setup, the +controller is not required to support ``SPI_MOSI_IDLE_HIGH`` but register access +is not possible. This connection mode saves one wire and works with any SPI +controller. + +Set the ``adi,sdi-pin`` device tree property to ``"high"`` to select this mode. + +:: + + +-------------+ + +--------------------| CS | + v | | + VIO +--------------------+ | HOST | + | | CNV | | | + +--->| SDI AD4000 SDO |-------->| SDI | + | SCK | | | + +--------------------+ | | + ^ | | + +--------------------| SCLK | + +-------------+ + +Alternatively, a GPIO may be connected to the device CNV pin. This is similar to +the previous wiring configuration but saves the use of a CS line. + +:: + + +-------------+ + +--------------------| GPIO | + v | | + VIO +--------------------+ | HOST | + | | CNV | | | + +--->| SDI AD4000 SDO |-------->| SDI | + | SCK | | | + +--------------------+ | | + ^ | | + +--------------------| SCLK | + +-------------+ + +CS mode, 4-wire without busy indicator +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +In datasheet "4-wire" mode, the controller CS line is connected to the ADC SDI +pin and a GPIO is connected to the ADC CNV pin. This connection mode may better +suit scenarios where multiple ADCs can share one CNV trigger. + +Set ``adi,sdi-pin`` to ``"cs"`` to select this mode. + + +:: + + +-------------+ + + ----------------------------------| CS | + | | | + | +-------------------| GPIO | + | v | | + | +--------------------+ | HOST | + | | CNV | | | + +--->| SDI AD4000 SDO |-------->| SDI | + | SCK | | | + +--------------------+ | | + ^ | | + +--------------------| SCLK | + +-------------+ |