mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/chenhuacai/linux-loongson
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1b3cee4123
Add device tree documentation for AD4170-4 and similar sigma-delta ADCs. The AD4170-4 is a 24-bit, multichannel, sigma-delta ADC. Acked-by: Conor Dooley <conor.dooley@microchip.com> Signed-off-by: Marcelo Schmitt <marcelo.schmitt@analog.com> Link: https://patch.msgid.link/aa4b3be541c7b759560f8e0c5340a456cb2f3801.1751895245.git.marcelo.schmitt@analog.com Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
555 lines
18 KiB
YAML
555 lines
18 KiB
YAML
# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
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%YAML 1.2
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---
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$id: http://devicetree.org/schemas/iio/adc/adi,ad4170-4.yaml#
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$schema: http://devicetree.org/meta-schemas/core.yaml#
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title: Analog Devices AD4170-4 and similar Analog to Digital Converters
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maintainers:
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- Marcelo Schmitt <marcelo.schmitt@analog.com>
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description: |
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Analog Devices AD4170-4 series of Sigma-delta Analog to Digital Converters.
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Specifications can be found at:
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https://www.analog.com/media/en/technical-documentation/data-sheets/ad4170-4.pdf
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https://www.analog.com/media/en/technical-documentation/data-sheets/ad4190-4.pdf
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https://www.analog.com/media/en/technical-documentation/data-sheets/ad4195-4.pdf
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$ref: /schemas/spi/spi-peripheral-props.yaml#
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$defs:
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reference-buffer:
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description: |
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Enable precharge buffer, full buffer, or skip reference buffering of
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the positive/negative voltage reference. Because the output impedance
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of the source driving the voltage reference inputs may be dynamic,
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resistive/capacitive combinations of those inputs can cause DC gain
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errors if the reference inputs go unbuffered into the ADC. Enable
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reference buffering if the provided reference source has dynamic high
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impedance output. Note the absolute voltage allowed on REFINn+ and REFINn-
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inputs is from AVSS - 50 mV to AVDD + 50 mV when the reference buffers are
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disabled but narrows to AVSS to AVDD when reference buffering is enabled
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or in precharge mode.
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$ref: /schemas/types.yaml#/definitions/string
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enum: [ precharge, full, disabled ]
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default: full
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properties:
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compatible:
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enum:
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- adi,ad4170-4
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- adi,ad4190-4
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- adi,ad4195-4
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avss-supply:
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description:
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Reference voltage supply for AVSS. A −2.625V minimum and 0V maximum supply
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that powers the chip. If not provided, AVSS is assumed to be at system
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ground (0V).
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avdd-supply:
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description:
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A supply of 4.75V to 5.25V relative to AVSS that powers the chip (AVDD).
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iovdd-supply:
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description: 1.7V to 5.25V reference supply to the serial interface (IOVDD).
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refin1p-supply:
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description: REFIN+ supply that can be used as reference for conversion.
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refin1n-supply:
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description: REFIN- supply that can be used as reference for conversion.
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refin2p-supply:
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description: REFIN2+ supply that can be used as reference for conversion.
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refin2n-supply:
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description: REFIN2- supply that can be used as reference for conversion.
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spi-cpol: true
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spi-cpha: true
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interrupts:
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description:
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Interrupt for signaling the completion of conversion results. The data
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ready signal (RDY) used as interrupt is by default provided on the SDO
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pin. Alternatively, it can be provided on the DIG_AUX1 pin in which case
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the chip disables the RDY function on SDO. Thus, there can be only one
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data ready interrupt enabled at a time.
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interrupt-names:
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description:
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Specify which pin should be configured as Data Ready interrupt.
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enum:
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- sdo
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- dig_aux1
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clocks:
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maxItems: 1
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description:
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Optional external clock source. Can specify either an external clock or
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external crystal.
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clock-names:
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enum:
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- ext-clk
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- xtal
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default: ext-clk
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'#clock-cells':
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const: 0
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clock-output-names:
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maxItems: 1
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gpio-controller: true
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"#gpio-cells":
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const: 2
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description: |
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The first cell is for the GPIO number: 0 to 3.
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The second cell takes standard GPIO flags.
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ldac-gpios:
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description:
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GPIO connected to DIG_AUX2 pin to be used as LDAC toggle to control the
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transfer of data from the DAC_INPUT_A register to the DAC.
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maxItems: 1
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'#address-cells':
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const: 1
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'#size-cells':
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const: 0
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adi,vbias-pins:
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description: Analog inputs to apply a voltage bias of (AVDD − AVSS) / 2 to.
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$ref: /schemas/types.yaml#/definitions/uint32-array
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minItems: 1
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maxItems: 9
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items:
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minimum: 0
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maximum: 8
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allOf:
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# Some devices don't have integrated DAC
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- if:
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properties:
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compatible:
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contains:
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enum:
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- adi,ad4190-4
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- adi,ad4195-4
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then:
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properties:
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ldac-gpios: false
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# Require to specify the interrupt pin when using interrupts
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- if:
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required:
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- interrupts
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then:
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required:
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- interrupt-names
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# If an external clock is set, the internal clock cannot go out and vice versa
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- oneOf:
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- required: [clocks]
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properties:
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'#clock-cells': false
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- required: ['#clock-cells']
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properties:
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clocks: false
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required:
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- compatible
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- reg
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- avdd-supply
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- iovdd-supply
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- spi-cpol
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- spi-cpha
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unevaluatedProperties: false
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patternProperties:
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"^channel@[0-9a-f]$":
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$ref: /schemas/iio/adc/adc.yaml#
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unevaluatedProperties: false
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description:
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Represents the external channels which are connected to the ADC.
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properties:
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reg:
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description:
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The channel number.
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minimum: 0
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maximum: 15
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diff-channels:
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description: |
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This property is used for defining the inputs of a differential
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voltage channel. The first value is the positive input and the second
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value is the negative input of the channel.
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Besides the analog input pins AIN0 to AIN8, there are special inputs
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that can be selected with the following values:
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17: Internal temperature sensor
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18: (AVDD-AVSS)/5
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19: (IOVDD-DGND)/5
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20: DAC output
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21: ALDO
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22: DLDO
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23: AVSS
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24: DGND
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25: REFIN+
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26: REFIN-
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27: REFIN2+
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28: REFIN2-
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29: REFOUT
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For the internal temperature sensor, use the input number for both
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inputs (i.e. diff-channels = <17 17>).
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items:
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enum: [0, 1, 2, 3, 4, 5, 6, 7, 8, 17, 18, 19, 20, 21, 22, 23, 24, 25,
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26, 27, 28, 29]
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adi,reference-select:
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description: |
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Select the reference source to use when converting on the
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specific channel. Valid values are:
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0: REFIN+/REFIN-
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1: REFIN2+/REFIN2−
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2: REFOUT/AVSS (internal reference)
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3: AVDD/AVSS
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If not specified, REFOUT/AVSS is used.
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$ref: /schemas/types.yaml#/definitions/uint32
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enum: [0, 1, 2, 3]
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default: 1
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adi,positive-reference-buffer:
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$ref: '#/$defs/reference-buffer'
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adi,negative-reference-buffer:
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$ref: '#/$defs/reference-buffer'
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adi,sensor-type:
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description:
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The AD4170-4 and similar designs have features to aid interfacing with
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load cell weigh scale, RTD, and thermocouple sensors. Each of those
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sensor types requires either distinct wiring configuration or
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external circuitry for proper sensor operation and can use different
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ADC chip functionality on their setups. A key characteristic of those
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external sensors is that they must be excited either by voltage supply
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or by ADC chip excitation signals. The sensor can then be read through
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a pair of analog inputs. This property specifies which particular
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sensor type is connected to the ADC so it can be properly setup and
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handled. Omit this property for conventional (not weigh scale, RTD, or
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thermocouple) ADC channel setups.
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$ref: /schemas/types.yaml#/definitions/string
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enum: [ weighscale, rtd, thermocouple ]
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adi,excitation-pin-0:
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description:
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Analog input to apply excitation current to while the channel
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is active.
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$ref: /schemas/types.yaml#/definitions/uint32
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minimum: 0
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maximum: 20
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default: 0
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adi,excitation-pin-1:
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description:
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Analog input to apply excitation current to while the channel
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is active.
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$ref: /schemas/types.yaml#/definitions/uint32
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minimum: 0
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maximum: 20
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default: 0
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adi,excitation-pin-2:
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description:
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Analog input to apply excitation current to while the channel
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is active.
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$ref: /schemas/types.yaml#/definitions/uint32
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minimum: 0
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maximum: 20
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default: 0
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adi,excitation-pin-3:
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description:
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Analog input to apply excitation current to while the channel
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is active.
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$ref: /schemas/types.yaml#/definitions/uint32
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minimum: 0
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maximum: 20
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default: 0
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adi,excitation-current-0-microamp:
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description:
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Excitation current in microamperes to be applied to pin specified in
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adi,excitation-pin-0 while this channel is active.
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enum: [0, 10, 50, 100, 250, 500, 1000, 1500]
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default: 0
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adi,excitation-current-1-microamp:
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description:
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Excitation current in microamperes to be applied to pin specified in
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adi,excitation-pin-1 while this channel is active.
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enum: [0, 10, 50, 100, 250, 500, 1000, 1500]
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default: 0
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adi,excitation-current-2-microamp:
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description:
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Excitation current in microamperes to be applied to pin specified in
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adi,excitation-pin-2 while this channel is active.
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enum: [0, 10, 50, 100, 250, 500, 1000, 1500]
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default: 0
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adi,excitation-current-3-microamp:
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description:
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Excitation current in microamperes to be applied to pin specified in
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adi,excitation-pin-3 while this channel is active.
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enum: [0, 10, 50, 100, 250, 500, 1000, 1500]
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default: 0
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adi,excitation-ac:
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type: boolean
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description:
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Whether the external sensor has to be AC or DC excited. When omitted,
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it is DC excited.
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allOf:
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- oneOf:
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- required: [single-channel, common-mode-channel]
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properties:
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diff-channels: false
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- required: [diff-channels]
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properties:
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single-channel: false
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common-mode-channel: false
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# Usual ADC channels don't need external circuitry excitation.
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- if:
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not:
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required:
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- adi,sensor-type
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then:
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properties:
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adi,excitation-pin-0: false
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adi,excitation-pin-1: false
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adi,excitation-pin-2: false
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adi,excitation-pin-3: false
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adi,excitation-current-0-microamp: false
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adi,excitation-current-1-microamp: false
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adi,excitation-current-2-microamp: false
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adi,excitation-current-3-microamp: false
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adi,excitation-ac: false
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# Weigh scale bridge AC excited with one pair of predefined signals.
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- if:
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allOf:
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- properties:
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adi,sensor-type:
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contains:
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const: weighscale
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- required:
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- adi,excitation-ac
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- adi,excitation-pin-2
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- adi,excitation-pin-3
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- not:
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required:
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- adi,excitation-current-2-microamp
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- adi,excitation-current-3-microamp
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then:
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properties:
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adi,excitation-pin-2:
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const: 19
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adi,excitation-pin-3:
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const: 20
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# Weigh scale bridge AC excited with two pairs of predefined signals.
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- if:
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allOf:
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- properties:
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adi,sensor-type:
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contains:
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const: weighscale
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- required:
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- adi,excitation-ac
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- adi,excitation-pin-0
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- adi,excitation-pin-1
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- adi,excitation-pin-2
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- adi,excitation-pin-3
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- not:
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required:
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- adi,excitation-current-0-microamp
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- adi,excitation-current-1-microamp
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- adi,excitation-current-2-microamp
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- adi,excitation-current-3-microamp
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then:
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properties:
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adi,excitation-pin-0:
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const: 17
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adi,excitation-pin-1:
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const: 18
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adi,excitation-pin-2:
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const: 19
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adi,excitation-pin-3:
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const: 20
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examples:
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- |
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#include <dt-bindings/interrupt-controller/irq.h>
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spi {
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#address-cells = <1>;
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#size-cells = <0>;
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adc@0 {
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compatible = "adi,ad4170-4";
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reg = <0>;
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spi-max-frequency = <20000000>;
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spi-cpol;
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spi-cpha;
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avdd-supply = <&avdd>;
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iovdd-supply = <&iovdd>;
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clocks = <&clk>;
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clock-names = "xtal";
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interrupts = <0 IRQ_TYPE_EDGE_FALLING>;
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interrupt-names = "dig_aux1";
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adi,vbias-pins = <8>;
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#address-cells = <1>;
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#size-cells = <0>;
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// Sample AIN0 with respect to DGND throughout AVDD/DGND input range
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// Pseudo-differential unipolar
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channel@0 {
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reg = <0>;
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single-channel = <0>;
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common-mode-channel = <24>;
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adi,reference-select = <3>;
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};
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// Weigh scale sensor
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channel@1 {
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reg = <1>;
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bipolar;
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diff-channels = <1 2>;
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adi,reference-select = <0>;
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adi,positive-reference-buffer = "precharge";
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adi,negative-reference-buffer = "precharge";
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adi,sensor-type = "weighscale";
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adi,excitation-pin-2 = <19>;
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adi,excitation-pin-3 = <20>;
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adi,excitation-ac;
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};
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// RTD sensor
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channel@2 {
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reg = <2>;
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bipolar;
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diff-channels = <3 4>;
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adi,reference-select = <0>;
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adi,sensor-type = "rtd";
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adi,excitation-pin-0 = <5>;
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adi,excitation-pin-1 = <6>;
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adi,excitation-current-0-microamp = <500>;
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adi,excitation-current-1-microamp = <500>;
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adi,excitation-ac;
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};
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// Thermocouple sensor
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channel@3 {
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reg = <3>;
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bipolar;
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diff-channels = <7 8>;
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adi,reference-select = <0>;
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adi,sensor-type = "thermocouple";
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adi,excitation-pin-0 = <18>;
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adi,excitation-current-0-microamp = <500>;
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};
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};
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};
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- |
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#include <dt-bindings/interrupt-controller/irq.h>
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spi {
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#address-cells = <1>;
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#size-cells = <0>;
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adc@0 {
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compatible = "adi,ad4170-4";
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reg = <0>;
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spi-max-frequency = <20000000>;
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spi-cpol;
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spi-cpha;
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avdd-supply = <&avdd>;
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iovdd-supply = <&iovdd>;
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#clock-cells = <0>;
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clock-output-names = "ad4170-clk16mhz";
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interrupts = <0 IRQ_TYPE_EDGE_FALLING>;
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interrupt-names = "dig_aux1";
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#address-cells = <1>;
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#size-cells = <0>;
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// Sample AIN0 with respect to AIN1 throughout AVDD/AVSS input range
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// Differential bipolar. If AVSS < 0V, differential true bipolar
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channel@0 {
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reg = <0>;
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bipolar;
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diff-channels = <0 1>;
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adi,reference-select = <3>;
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};
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// Sample AIN2 with respect to DGND throughout AVDD/DGND input range
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// Pseudo-differential unipolar
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channel@1 {
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reg = <1>;
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single-channel = <2>;
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common-mode-channel = <24>;
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adi,reference-select = <3>;
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};
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// Sample AIN3 with respect to 2.5V throughout AVDD/AVSS input range
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// Pseudo-differential bipolar
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channel@2 {
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reg = <2>;
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bipolar;
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single-channel = <3>;
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common-mode-channel = <29>;
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adi,reference-select = <3>;
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};
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// Sample AIN4 with respect to DGND throughout AVDD/AVSS input range
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// Pseudo-differential bipolar
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channel@3 {
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reg = <3>;
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bipolar;
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single-channel = <4>;
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common-mode-channel = <24>;
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adi,reference-select = <3>;
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};
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// Sample AIN5 with respect to 2.5V throughout AVDD/AVSS input range
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// Pseudo-differential unipolar (AD4170-4 datasheet page 46 example)
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channel@4 {
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reg = <4>;
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single-channel = <5>;
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common-mode-channel = <29>;
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adi,reference-select = <3>;
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};
|
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// Sample AIN6 with respect to 2.5V throughout REFIN+/REFIN- input range
|
||
// Pseudo-differential bipolar
|
||
channel@5 {
|
||
reg = <5>;
|
||
bipolar;
|
||
single-channel = <6>;
|
||
common-mode-channel = <29>;
|
||
adi,reference-select = <0>;
|
||
};
|
||
// Weigh scale sensor
|
||
channel@6 {
|
||
reg = <6>;
|
||
bipolar;
|
||
diff-channels = <7 8>;
|
||
adi,reference-select = <0>;
|
||
adi,sensor-type = "weighscale";
|
||
adi,excitation-pin-0 = <17>;
|
||
adi,excitation-pin-1 = <18>;
|
||
adi,excitation-pin-2 = <19>;
|
||
adi,excitation-pin-3 = <20>;
|
||
adi,excitation-ac;
|
||
};
|
||
};
|
||
};
|
||
...
|