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# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
%YAML 1.2
---
$id: http://devicetree.org/schemas/iio/adc/adi,ad7944.yaml#
$schema: http://devicetree.org/meta-schemas/core.yaml#
title: Analog Devices PulSAR LFCSP Analog to Digital Converters
maintainers:
- Michael Hennerich <Michael.Hennerich@analog.com>
- Nuno Sá <nuno.sa@analog.com>
description: |
A family of pin-compatible single channel differential analog to digital
converters with SPI support in a LFCSP package.
* https://www.analog.com/en/products/ad7944.html
* https://www.analog.com/en/products/ad7985.html
* https://www.analog.com/en/products/ad7986.html
$ref: /schemas/spi/spi-peripheral-props.yaml#
properties:
compatible:
enum:
- adi,ad7944
- adi,ad7985
- adi,ad7986
reg:
maxItems: 1
spi-max-frequency:
maximum: 111111111
spi-cpol: true
spi-cpha: true
adi,spi-mode:
$ref: /schemas/types.yaml#/definitions/string
enum: [ single, chain ]
description: |
This property indicates the SPI wiring configuration.
When this property is omitted, it is assumed that the device is using what
the datasheet calls "4-wire mode". This is the conventional SPI mode used
when there are multiple devices on the same bus. In this mode, the CNV
line is used to initiate the conversion and the SDI line is connected to
CS on the SPI controller.
When this property is present, it indicates that the device is using one
of the following alternative wiring configurations:
* single: The datasheet calls this "3-wire mode". (NOTE: The datasheet's
definition of 3-wire mode is NOT at all related to the standard
spi-3wire property!) This mode is often used when the ADC is the only
device on the bus. In this mode, SDI is tied to VIO, and the CNV line
can be connected to the CS line of the SPI controller or to a GPIO, in
which case the CS line of the controller is unused.
* chain: The datasheet calls this "chain mode". This mode is used to save
on wiring when multiple ADCs are used. In this mode, the SDI line of
one chip is tied to the SDO of the next chip in the chain and the SDI of
the last chip in the chain is tied to GND. Only the first chip in the
chain is connected to the SPI bus. The CNV line of all chips are tied
together. The CS line of the SPI controller can be used as the CNV line
only if it is active high.
'#daisy-chained-devices': true
avdd-supply:
description: A 2.5V supply that powers the analog circuitry.
dvdd-supply:
description: A 2.5V supply that powers the digital circuitry.
vio-supply:
description:
A 1.8V to 2.7V supply for the digital inputs and outputs.
bvdd-supply:
description:
A voltage supply for the buffered power. When using an external reference
without an internal buffer (PDREF high, REFIN low), this should be
connected to the same supply as ref-supply. Otherwise, when using an
internal reference or an external reference with an internal buffer, this
is connected to a 5V supply.
ref-supply:
description:
Voltage regulator for the external reference voltage (REF). This property
is omitted when using an internal reference.
refin-supply:
description:
Voltage regulator for the reference buffer input (REFIN). When using an
external buffer with internal reference, this should be connected to a
1.2V external reference voltage supply. Otherwise, this property is
omitted.
cnv-gpios:
description:
The Convert Input (CNV). This input has multiple functions. It initiates
the conversions and selects the SPI mode of the device (chain or CS). In
'single' mode, this property is omitted if the CNV pin is connected to the
CS line of the SPI controller.
maxItems: 1
turbo-gpios:
description:
GPIO connected to the TURBO line. If omitted, it is assumed that the TURBO
line is hard-wired and the state is determined by the adi,always-turbo
property.
maxItems: 1
adi,always-turbo:
type: boolean
description:
When present, this property indicates that the TURBO line is hard-wired
and the state is always high. If neither this property nor turbo-gpios is
present, the TURBO line is assumed to be hard-wired and the state is
always low.
interrupts:
description:
The SDO pin can also function as a busy indicator. This node should be
connected to an interrupt that is triggered when the SDO line goes low
while the SDI line is high and the CNV line is low ('single' mode) or the
SDI line is low and the CNV line is high ('multi' mode); or when the SDO
line goes high while the SDI and CNV lines are high (chain mode),
maxItems: 1
required:
- compatible
- reg
- avdd-supply
- dvdd-supply
- vio-supply
- bvdd-supply
allOf:
# ref-supply and refin-supply are mutually exclusive (neither is also valid)
- if:
required:
- ref-supply
then:
properties:
refin-supply: false
- if:
required:
- refin-supply
then:
properties:
ref-supply: false
# in '4-wire' mode, cnv-gpios is required, for other modes it is optional
- if:
not:
required:
- adi,spi-mode
then:
required:
- cnv-gpios
# chain mode has lower SCLK max rate and doesn't work when TURBO is enabled
- if:
required:
- adi,spi-mode
properties:
adi,spi-mode:
const: chain
then:
properties:
spi-max-frequency:
maximum: 90909090
adi,always-turbo: false
required:
- '#daisy-chained-devices'
else:
properties:
'#daisy-chained-devices': false
# turbo-gpios and adi,always-turbo are mutually exclusive
- if:
required:
- turbo-gpios
then:
properties:
adi,always-turbo: false
- if:
required:
- adi,always-turbo
then:
properties:
turbo-gpios: false
unevaluatedProperties: false
examples:
- |
#include <dt-bindings/gpio/gpio.h>
spi {
#address-cells = <1>;
#size-cells = <0>;
adc@0 {
compatible = "adi,ad7944";
reg = <0>;
spi-cpha;
spi-max-frequency = <111111111>;
avdd-supply = <&supply_2_5V>;
dvdd-supply = <&supply_2_5V>;
vio-supply = <&supply_1_8V>;
bvdd-supply = <&supply_5V>;
cnv-gpios = <&gpio 0 GPIO_ACTIVE_HIGH>;
turbo-gpios = <&gpio 1 GPIO_ACTIVE_HIGH>;
};
};
|
