1 # SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
2 %YAML 1.2
3 ---
4 $id: http://devicetree.org/schemas/iio/adc/adi,ad7944.yaml#
5 $schema: http://devicetree.org/meta-schemas/core.yaml#
6
7 title: Analog Devices PulSAR LFCSP Analog to Digital Converters
8
9 maintainers:
10 - Michael Hennerich <Michael.Hennerich@analog.com>
11 - Nuno Sá <nuno.sa@analog.com>
12
13 description: |
14 A family of pin-compatible single channel differential analog to digital
15 converters with SPI support in a LFCSP package.
16
17 * https://www.analog.com/en/products/ad7944.html
18 * https://www.analog.com/en/products/ad7985.html
19 * https://www.analog.com/en/products/ad7986.html
20
21 $ref: /schemas/spi/spi-peripheral-props.yaml#
22
23 properties:
24 compatible:
25 enum:
26 - adi,ad7944
27 - adi,ad7985
28 - adi,ad7986
29
30 reg:
31 maxItems: 1
32
33 spi-max-frequency:
34 maximum: 111111111
35
36 spi-cpol: true
37 spi-cpha: true
38
39 adi,spi-mode:
40 $ref: /schemas/types.yaml#/definitions/string
41 enum: [ single, chain ]
42 description: |
43 This property indicates the SPI wiring configuration.
44
45 When this property is omitted, it is assumed that the device is using what
46 the datasheet calls "4-wire mode". This is the conventional SPI mode used
47 when there are multiple devices on the same bus. In this mode, the CNV
48 line is used to initiate the conversion and the SDI line is connected to
49 CS on the SPI controller.
50
51 When this property is present, it indicates that the device is using one
52 of the following alternative wiring configurations:
53
54 * single: The datasheet calls this "3-wire mode". (NOTE: The datasheet's
55 definition of 3-wire mode is NOT at all related to the standard
56 spi-3wire property!) This mode is often used when the ADC is the only
57 device on the bus. In this mode, SDI is tied to VIO, and the CNV line
58 can be connected to the CS line of the SPI controller or to a GPIO, in
59 which case the CS line of the controller is unused.
60 * chain: The datasheet calls this "chain mode". This mode is used to save
61 on wiring when multiple ADCs are used. In this mode, the SDI line of
62 one chip is tied to the SDO of the next chip in the chain and the SDI of
63 the last chip in the chain is tied to GND. Only the first chip in the
64 chain is connected to the SPI bus. The CNV line of all chips are tied
65 together. The CS line of the SPI controller can be used as the CNV line
66 only if it is active high.
67
68 '#daisy-chained-devices': true
69
70 avdd-supply:
71 description: A 2.5V supply that powers the analog circuitry.
72
73 dvdd-supply:
74 description: A 2.5V supply that powers the digital circuitry.
75
76 vio-supply:
77 description:
78 A 1.8V to 2.7V supply for the digital inputs and outputs.
79
80 bvdd-supply:
81 description:
82 A voltage supply for the buffered power. When using an external reference
83 without an internal buffer (PDREF high, REFIN low), this should be
84 connected to the same supply as ref-supply. Otherwise, when using an
85 internal reference or an external reference with an internal buffer, this
86 is connected to a 5V supply.
87
88 ref-supply:
89 description:
90 Voltage regulator for the external reference voltage (REF). This property
91 is omitted when using an internal reference.
92
93 refin-supply:
94 description:
95 Voltage regulator for the reference buffer input (REFIN). When using an
96 external buffer with internal reference, this should be connected to a
97 1.2V external reference voltage supply. Otherwise, this property is
98 omitted.
99
100 cnv-gpios:
101 description:
102 The Convert Input (CNV). This input has multiple functions. It initiates
103 the conversions and selects the SPI mode of the device (chain or CS). In
104 'single' mode, this property is omitted if the CNV pin is connected to the
105 CS line of the SPI controller.
106 maxItems: 1
107
108 turbo-gpios:
109 description:
110 GPIO connected to the TURBO line. If omitted, it is assumed that the TURBO
111 line is hard-wired and the state is determined by the adi,always-turbo
112 property.
113 maxItems: 1
114
115 adi,always-turbo:
116 type: boolean
117 description:
118 When present, this property indicates that the TURBO line is hard-wired
119 and the state is always high. If neither this property nor turbo-gpios is
120 present, the TURBO line is assumed to be hard-wired and the state is
121 always low.
122
123 interrupts:
124 description:
125 The SDO pin can also function as a busy indicator. This node should be
126 connected to an interrupt that is triggered when the SDO line goes low
127 while the SDI line is high and the CNV line is low ('single' mode) or the
128 SDI line is low and the CNV line is high ('multi' mode); or when the SDO
129 line goes high while the SDI and CNV lines are high (chain mode),
130 maxItems: 1
131
132 required:
133 - compatible
134 - reg
135 - avdd-supply
136 - dvdd-supply
137 - vio-supply
138 - bvdd-supply
139
140 allOf:
141 # ref-supply and refin-supply are mutually exclusive (neither is also valid)
142 - if:
143 required:
144 - ref-supply
145 then:
146 properties:
147 refin-supply: false
148 - if:
149 required:
150 - refin-supply
151 then:
152 properties:
153 ref-supply: false
154 # in '4-wire' mode, cnv-gpios is required, for other modes it is optional
155 - if:
156 not:
157 required:
158 - adi,spi-mode
159 then:
160 required:
161 - cnv-gpios
162 # chain mode has lower SCLK max rate and doesn't work when TURBO is enabled
163 - if:
164 required:
165 - adi,spi-mode
166 properties:
167 adi,spi-mode:
168 const: chain
169 then:
170 properties:
171 spi-max-frequency:
172 maximum: 90909090
173 adi,always-turbo: false
174 required:
175 - '#daisy-chained-devices'
176 else:
177 properties:
178 '#daisy-chained-devices': false
179 # turbo-gpios and adi,always-turbo are mutually exclusive
180 - if:
181 required:
182 - turbo-gpios
183 then:
184 properties:
185 adi,always-turbo: false
186 - if:
187 required:
188 - adi,always-turbo
189 then:
190 properties:
191 turbo-gpios: false
192
193 unevaluatedProperties: false
194
195 examples:
196 - |
197 #include <dt-bindings/gpio/gpio.h>
198 spi {
199 #address-cells = <1>;
200 #size-cells = <0>;
201 adc@0 {
202 compatible = "adi,ad7944";
203 reg = <0>;
204 spi-cpha;
205 spi-max-frequency = <111111111>;
206 avdd-supply = <&supply_2_5V>;
207 dvdd-supply = <&supply_2_5V>;
208 vio-supply = <&supply_1_8V>;
209 bvdd-supply = <&supply_5V>;
210 cnv-gpios = <&gpio 0 GPIO_ACTIVE_HIGH>;
211 turbo-gpios = <&gpio 1 GPIO_ACTIVE_HIGH>;
212 };
213 };
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