Lines Matching +full:spi +full:- +full:sck +full:- +full:cs +full:- +full:delay
1 .. SPDX-License-Identifier: GPL-2.0-only
41 * `AD7988-1 <https://www.analog.com/AD7988-1>`_
42 * `AD7988-5 <https://www.analog.com/AD7988-5>`_
45 ------------------
47 Devices of the AD4000 series can be connected to the SPI host controller in a
50 CS mode, 3-wire turbo mode
53 Datasheet "3-wire" mode is what most resembles standard SPI connection which,
54 for these devices, comprises of connecting the controller CS line to device CNV
55 pin and other SPI lines as usual. This configuration is (misleadingly) called
56 "CS Mode, 3-Wire Turbo Mode" connection in datasheets.
57 NOTE: The datasheet definition of 3-wire mode for the AD4000 series is NOT the
58 same of standard spi-3wire mode.
60 it requires the SPI controller to support the ``SPI_MOSI_IDLE_HIGH`` feature.
62 Omit the ``adi,sdi-pin`` property in device tree to select this mode.
66 +-------------+
67 + ----------------------------------| SDO |
69 | +-------------------| CS |
71 | +--------------------+ | HOST |
73 +--->| SDI AD4000 SDO |-------->| SDI |
74 | SCK | | |
75 +--------------------+ | |
77 +--------------------| SCLK |
78 +-------------+
80 CS mode, 3-wire, without busy indicator
83 Another wiring configuration supported as "3-wire" mode has the SDI pin
84 hard-wired to digital input/output interface supply (VIO). In this setup, the
86 is not possible. This connection mode saves one wire and works with any SPI
89 Set the ``adi,sdi-pin`` device tree property to ``"high"`` to select this mode.
93 +-------------+
94 +--------------------| CS |
96 VIO +--------------------+ | HOST |
98 +--->| SDI AD4000 SDO |-------->| SDI |
99 | SCK | | |
100 +--------------------+ | |
102 +--------------------| SCLK |
103 +-------------+
106 the previous wiring configuration but saves the use of a CS line.
110 +-------------+
111 +--------------------| GPIO |
113 VIO +--------------------+ | HOST |
115 +--->| SDI AD4000 SDO |-------->| SDI |
116 | SCK | | |
117 +--------------------+ | |
119 +--------------------| SCLK |
120 +-------------+
122 CS mode, 4-wire without busy indicator
125 In datasheet "4-wire" mode, the controller CS line is connected to the ADC SDI
129 Set ``adi,sdi-pin`` to ``"cs"`` to select this mode.
134 +-------------+
135 + ----------------------------------| CS |
137 | +-------------------| GPIO |
139 | +--------------------+ | HOST |
141 +--->| SDI AD4000 SDO |-------->| SDI |
142 | SCK | | |
143 +--------------------+ | |
145 +--------------------| SCLK |
146 +-------------+
151 The AD4000 series driver supports differential and pseudo-differential ADCs.
156 configuration register, which is only possible when the ADC is wired in 3-wire
157 turbo mode, and the SPI controller is ``SPI_MOSI_IDLE_HIGH`` capable. If those
160 Besides that, differential and pseudo-differential voltage channels present
163 Pseudo-differential ADCs
164 ------------------------
166 Typical voltage channel attributes of a pseudo-differential AD4000 series device:
168 +-------------------------------------------+------------------------------------------+
172 +-------------------------------------------+------------------------------------------+
174 +-------------------------------------------+------------------------------------------+
176 +-------------------------------------------+------------------------------------------+
178 +-------------------------------------------+------------------------------------------+
181 -----------------
185 +-------------------------------------------+------------------------------------------+
188 | ``in_voltage0-voltage1_raw`` | Raw ADC output code. |
189 +-------------------------------------------+------------------------------------------+
190 | ``in_voltage0-voltage1_scale`` | Scale factor to convert raw value to mV. |
191 +-------------------------------------------+------------------------------------------+
192 | ``in_voltage0-voltage1_scale_available`` | Toggles input span compression |
193 +-------------------------------------------+------------------------------------------+
195 SPI offload support
196 -------------------
198 To be able to achieve the maximum sample rate, the driver can be used with SPI
199 offload engines such as the one usually present in `AXI SPI Engine`_, to provide
200 SPI offload support.
202 .. _AXI SPI Engine: http://analogdevicesinc.github.io/hdl/projects/pulsar_adc/index.html
204 To keep up with SPI offloading transfer speeds, the ADC must be connected either
205 in 3-wire turbo mode or in 3-wire without busy indicator mode and have SPI
206 controller CS line connected to the CNV pin.
208 When set for SPI offload support, the IIO device will provide different
212 ``in_voltage0-voltage1_sampling_frequency`` file is provided to allow setting
217 Also, because the ADC output has a one sample latency (delay) when the device is
218 wired in "3-wire" mode and only one transfer per sample is done when using SPI