| # 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 */ |
| }; |
| ... |
