[PATCH v3 1/3] dt-bindings: iio: adc: avia-hx711: add avia,hx710b compatible

Piyush Patle
2026-04-22T17:59:24Z

The HX710B shares the same two-wire interface as the HX711 but differs
in its channel and gain model: gain is fixed at 128 and the number of
trailing PD_SCK pulses selects the input channel rather than the gain.

Add avia,hx710b to the compatible enum. Document the chip differences
in the description and add chip-specific supply properties (dvdd-supply,
vsup-supply) for the HX711, a rate-gpios property for the HX711 RATE
pin, and an allOf constraint that forbids HX711-only properties on
HX710B nodes. Clarify the clock-frequency description to reflect its
actual purpose: controlling the SCK bit-bang timing.

Signed-off-by: Piyush Patle <piyushpatle228@gmail.com>
---
Changes in v3:
- Drop the vref-supply mention from avdd-supply; no such binding
property exists.
- Drop the clock-frequency sentence that repeated the schema default.
- Restore the example node name to weight.
- Remove the separate HX710B example.

Changes in v2:
- Remove driver implementation details from the description and describe
hardware behaviour only.
- Drop unrelated punctuation cleanup.
- Add dvdd-supply and vsup-supply optional properties for HX711.
- Add rate-gpios optional property for the HX711 RATE pin and forbid it
on HX710B.
- Add the allOf if/then block forbidding HX711-only properties on
HX710B nodes.
- Clarify clock-frequency as SCK bit-bang timing, not a crystal or
external clock input.
- Sort compatible enum alphabetically.
- Remove redundant example comments.
- Update the HX711 example to exercise rate-gpios.

.../bindings/iio/adc/avia-hx711.yaml | 50 +++++++++++++++----
1 file changed, 41 insertions(+), 9 deletions(-)

diff --git a/Documentation/devicetree/bindings/iio/adc/avia-hx711.yaml b/Documentation/devicetree/bindings/iio/adc/avia-hx711.yaml
index 9c57eb13f892..0c7c5843b8d2 100644
--- a/Documentation/devicetree/bindings/iio/adc/avia-hx711.yaml
+++ b/Documentation/devicetree/bindings/iio/adc/avia-hx711.yaml
@@ -4,24 +4,24 @@
$id: http://devicetree.org/schemas/iio/adc/avia-hx711.yaml#
$schema: http://devicetree.org/meta-schemas/core.yaml#

-title: AVIA HX711 ADC chip for weight cells
+title: AVIA HX711 and HX710B ADCs

maintainers:
- Andreas Klinger <ak@it-klinger.de>

description: |
- Bit-banging driver using two GPIOs:
- - sck-gpio gives a clock to the sensor with 24 cycles for data retrieval
- and up to 3 cycles for selection of the input channel and gain for the
- next measurement
- - dout-gpio is the sensor data the sensor responds to the clock
+ The HX711 is a 24-bit ADC with selectable gain (32/64/128) and two
+ differential input channels. Channel A supports gain 64 and 128;
+ channel B supports gain 32.

- Specifications about the driver can be found at:
- http://www.aviaic.com/ENProducts.aspx
+ The HX710B is a 24-bit ADC with fixed gain of 128. Channel 0 is the
+ differential input and channel 1 measures the DVDD-AVDD supply
+ voltage difference.

properties:
compatible:
enum:
+ - avia,hx710b
- avia,hx711

sck-gpios:
@@ -40,13 +40,44 @@ properties:

avdd-supply:
description:
- Definition of the regulator used as analog supply
+ Analog supply voltage (AVDD). Also serves as the voltage reference on
+ both chips.
+
+ dvdd-supply:
+ description:
+ Digital supply voltage (DVDD). HX711 only.
+
+ vsup-supply:
+ description:
+ Supply voltage for the on-chip regulator (VSUP). HX711 only.
+
+ rate-gpios:
+ description:
+ GPIO connected to the RATE pin (HX711 only). When driven low the
+ output data rate is 10 SPS; when driven high it is 80 SPS. If
+ omitted the RATE pin state is determined by the board wiring.
+ maxItems: 1

clock-frequency:
+ description:
+ Controls the SCK bit-bang timing. The value is used to derive the
+ delay between SCK edges; keep the SCK high time below 60 us to
+ avoid triggering chip power-down mode.
minimum: 20000
maximum: 2500000
default: 400000

+allOf:
+ - if:
+ properties:
+ compatible:
+ const: avia,hx710b
+ then:
+ properties:
+ vsup-supply: false
+ dvdd-supply: false
+ rate-gpios: false
+
required:
- compatible
- sck-gpios
@@ -62,6 +93,7 @@ examples:
compatible = "avia,hx711";
sck-gpios = <&gpio3 10 GPIO_ACTIVE_HIGH>;
dout-gpios = <&gpio0 7 GPIO_ACTIVE_HIGH>;
+ rate-gpios = <&gpio0 9 GPIO_ACTIVE_HIGH>;
avdd-supply = <&avdd>;
clock-frequency = <100000>;
};
--
2.43.0