Documentation/iio/ad4000.rst

   1 .. SPDX-License-Identifier: GPL-2.0-only
   2
   3 =============
   4 AD4000 driver
   5 =============
   6
   7 Device driver for Analog Devices Inc. AD4000 series of ADCs.
   8
   9 Supported devices
  10 =================
  11
  12 * `AD4000 <https://www.analog.com/AD4000>`_
  13 * `AD4001 <https://www.analog.com/AD4001>`_
  14 * `AD4002 <https://www.analog.com/AD4002>`_
  15 * `AD4003 <https://www.analog.com/AD4003>`_
  16 * `AD4004 <https://www.analog.com/AD4004>`_
  17 * `AD4005 <https://www.analog.com/AD4005>`_
  18 * `AD4006 <https://www.analog.com/AD4006>`_
  19 * `AD4007 <https://www.analog.com/AD4007>`_
  20 * `AD4008 <https://www.analog.com/AD4008>`_
  21 * `AD4010 <https://www.analog.com/AD4010>`_
  22 * `AD4011 <https://www.analog.com/AD4011>`_
  23 * `AD4020 <https://www.analog.com/AD4020>`_
  24 * `AD4021 <https://www.analog.com/AD4021>`_
  25 * `AD4022 <https://www.analog.com/AD4022>`_
  26 * `ADAQ4001 <https://www.analog.com/ADAQ4001>`_
  27 * `ADAQ4003 <https://www.analog.com/ADAQ4003>`_
  28
  29 Wiring connections
  30 ------------------
  31
  32 Devices of the AD4000 series can be connected to the SPI host controller in a
  33 few different modes.
  34
  35 CS mode, 3-wire turbo mode
  36 ^^^^^^^^^^^^^^^^^^^^^^^^^^
  37
  38 Datasheet "3-wire" mode is what most resembles standard SPI connection which,
  39 for these devices, comprises of connecting the controller CS line to device CNV
  40 pin and other SPI lines as usual. This configuration is (misleadingly) called
  41 "CS Mode, 3-Wire Turbo Mode" connection in datasheets.
  42 NOTE: The datasheet definition of 3-wire mode for the AD4000 series is NOT the
  43 same of standard spi-3wire mode.
  44 This is the only connection mode that allows configuration register access but
  45 it requires the SPI controller to support the ``SPI_MOSI_IDLE_HIGH`` feature.
  46
  47 Omit the ``adi,sdi-pin`` property in device tree to select this mode.
  48
  49 ::
  50
  51                                          +-------------+
  52      + ----------------------------------| SDO         |
  53      |                                   |             |
  54      |               +-------------------| CS          |
  55      |               v                   |             |
  56      |    +--------------------+         |     HOST    |
  57      |    |        CNV         |         |             |
  58      +--->| SDI   AD4000   SDO |-------->| SDI         |
  59           |        SCK         |         |             |
  60           +--------------------+         |             |
  61                     ^                    |             |
  62                     +--------------------| SCLK        |
  63                                          +-------------+
  64
  65 CS mode, 3-wire, without busy indicator
  66 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  67
  68 Another wiring configuration supported as "3-wire" mode has the SDI pin
  69 hard-wired to digital input/output interface supply (VIO). In this setup, the
  70 controller is not required to support ``SPI_MOSI_IDLE_HIGH`` but register access
  71 is not possible. This connection mode saves one wire and works with any SPI
  72 controller.
  73
  74 Set the ``adi,sdi-pin`` device tree property to ``"high"`` to select this mode.
  75
  76 ::
  77
  78                                          +-------------+
  79                     +--------------------| CS          |
  80                     v                    |             |
  81     VIO   +--------------------+         |     HOST    |
  82      |    |        CNV         |         |             |
  83      +--->| SDI   AD4000   SDO |-------->| SDI         |
  84           |        SCK         |         |             |
  85           +--------------------+         |             |
  86                     ^                    |             |
  87                     +--------------------| SCLK        |
  88                                          +-------------+
  89
  90 Alternatively, a GPIO may be connected to the device CNV pin. This is similar to
  91 the previous wiring configuration but saves the use of a CS line.
  92
  93 ::
  94
  95                                          +-------------+
  96                     +--------------------| GPIO        |
  97                     v                    |             |
  98     VIO   +--------------------+         |     HOST    |
  99      |    |        CNV         |         |             |
 100      +--->| SDI   AD4000   SDO |-------->| SDI         |
 101           |        SCK         |         |             |
 102           +--------------------+         |             |
 103                     ^                    |             |
 104                     +--------------------| SCLK        |
 105                                          +-------------+
 106
 107 CS mode, 4-wire without busy indicator
 108 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 109
 110 In datasheet "4-wire" mode, the controller CS line is connected to the ADC SDI
 111 pin and a GPIO is connected to the ADC CNV pin. This connection mode may better
 112 suit scenarios where multiple ADCs can share one CNV trigger.
 113
 114 Set ``adi,sdi-pin`` to ``"cs"`` to select this mode.
 115
 116
 117 ::
 118
 119                                          +-------------+
 120      + ----------------------------------| CS          |
 121      |                                   |             |
 122      |               +-------------------| GPIO        |
 123      |               v                   |             |
 124      |    +--------------------+         |     HOST    |
 125      |    |        CNV         |         |             |
 126      +--->| SDI   AD4000   SDO |-------->| SDI         |
 127           |        SCK         |         |             |
 128           +--------------------+         |             |
 129                     ^                    |             |
 130                     +--------------------| SCLK        |
 131                                          +-------------+