dts/bindings/comparator/st,stm32-comp.yaml

# Copyright (c) 2025 Alexander Kozhinov <ak.alexander.kozhinov@gmail.com>
# SPDX-License-Identifier: Apache-2.0

description: |
  STM32 Comparator

  The following example displays the minimum node layout:

    comp1: comparator@40010200 {
      reg = <0x40010200 0x4>;
      interrupts = <64 0>;
      clocks = <&rcc STM32_CLOCK(APB2, 0)>;
      st,exti-line = <21>;
      positive-input = "IN0";
      negative-input = "VREFINT";
      status = "okay";
    };

  NOTE: The shown example is for stm32g474re

  Enabling the comparator node requires setting the minimum default
  configuration of the comparator. This includes selecting the
  positive and negative inputs, and routing them using pinctrl:

    &comp1 {
      pinctrl-0 = <&comp1_inp_pa1 &comp1_out_pa6>;
      pinctrl-names = "default";

      positive-input = "IN0";
      negative-input = "VREFINT";
      status = "okay";
    };

  NOTE: Pins used above are an example for stm32g474re

compatible: "st,stm32-comp"

include:
  - base.yaml
  - pinctrl-device.yaml

properties:
  reg:
    required: true
  interrupts:
    required: true
  clocks:
    required: true

  invert-output:
    type: string
    description: |
      Output polarity selection.
    enum:
      - NONINVERTED
      - INVERTED
    default: NONINVERTED

  st,exti-line:
    required: true
    type: int
    description: |
      EXTI interrupt line number connected to the comparator (COMPx) event.

  st,lock-enable:
    type: boolean
    description: |
      The comparator configuration can be locked to prevent any
      modification until the next system reset.
      Once the lock bit is set, it can be cleared only by a system reset.
      This feature allows to protect the comparator configuration against
      unintentional modification.

  positive-input:
    required: true
    type: string
    description: |
      Selects positive input pin provided by the pinmux controller.
      IN0 corresponds to the first pinmux option, IN1 to the second one.
    enum:
      - IN0
      - IN1

  negative-input:
    required: true
    type: string
    description: |
      Selects negative input. May be a package pin (IN0 / IN1) via pinctrl
      or an internal signal (e.g. VREFINT, DAC).
      In case of package pin assignment IN0 will correspond to first pinmux pin
      option and IN1 to the second one.
    enum:
      - 1_4VREFINT
      - 1_2VREFINT
      - 3_4VREFINT
      - VREFINT
      - IN0
      - IN1

  hysteresis:
    type: string
    description: |
      Selects the hysteresis voltage level.
      Hysteresis adds a voltage offset to the comparator threshold to prevent
      unwanted output toggling when the input voltage is noisy or slowly
      varying around the comparator threshold.
    enum:
      - NONE
      - LOW
      - MEDIUM
      - HIGH
    default: NONE

  st,blank-sel:
    type: string
    description: |
      Blanking source to mask short spikes at PWM period start.
      Ref (example): STM32G4 RM0440 Rev 8, 24.3.6.
    enum:
      - NONE
    default: NONE