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Diffstat (limited to 'dts/Bindings/iio/afe/voltage-divider.yaml')
-rw-r--r-- | dts/Bindings/iio/afe/voltage-divider.yaml | 86 |
1 files changed, 86 insertions, 0 deletions
diff --git a/dts/Bindings/iio/afe/voltage-divider.yaml b/dts/Bindings/iio/afe/voltage-divider.yaml new file mode 100644 index 0000000000..df2589f214 --- /dev/null +++ b/dts/Bindings/iio/afe/voltage-divider.yaml @@ -0,0 +1,86 @@ +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause) +%YAML 1.2 +--- +$id: http://devicetree.org/schemas/iio/afe/voltage-divider.yaml# +$schema: http://devicetree.org/meta-schemas/core.yaml# + +title: Voltage divider + +maintainers: + - Peter Rosin <peda@axentia.se> + +description: | + When an io-channel measures the midpoint of a voltage divider, the + interesting voltage is often the voltage over the full resistance + of the divider. This binding describes the voltage divider in such + a curcuit. + + Vin ----. + | + .-----. + | R | + '-----' + | + +---- Vout + | + .-----. + | Rout| + '-----' + | + GND + + +properties: + compatible: + const: voltage-divider + + io-channels: + maxItems: 1 + description: | + Channel node of a voltage io-channel. + + output-ohms: + description: + Resistance Rout over which the output voltage is measured. See full-ohms. + + full-ohms: + description: + Resistance R + Rout for the full divider. The io-channel is scaled by + the Rout / (R + Rout) quotient. + +required: + - compatible + - io-channels + - output-ohms + - full-ohms + +additionalProperties: false + +examples: + - | + #include <dt-bindings/interrupt-controller/irq.h> + /* + * The system voltage is circa 12V, but divided down with a 22/222 + * voltage divider (R = 200 Ohms, Rout = 22 Ohms) and fed to an ADC. + */ + spi { + #address-cells = <1>; + #size-cells = <0>; + maxadc: adc@0 { + compatible = "maxim,max1027"; + reg = <0>; + #io-channel-cells = <1>; + interrupt-parent = <&gpio5>; + interrupts = <15 IRQ_TYPE_EDGE_RISING>; + spi-max-frequency = <1000000>; + }; + }; + sysv { + compatible = "voltage-divider"; + io-channels = <&maxadc 1>; + + /* Scale the system voltage by 22/222 to fit the ADC range. */ + output-ohms = <22>; + full-ohms = <222>; /* 200 + 22 */ + }; +... |