dts/bindings/input/st,stmpe811.yaml

# Copyright (c) 2023 Antmicro <www.antmicro.com>
# SPDX-License-Identifier: Apache-2.0

description: STMPE811 I2C touchscreen controller

compatible: "st,stmpe811"

include: i2c-device.yaml

properties:
  int-gpios:
    type: phandle-array
    description: |
      Interrupt GPIO. Used by the controller to signal touch data is
      available. Active low.

  screen-width:
    type: int
    default: 0
    description: |
      Screen width for scaling the reported coordinates.
      Default: raw touchscreen resolution.

  screen-height:
    type: int
    default: 0
    description: |
      Screen height for scaling the reported coordinates.
      Default: raw touchscreen resolution.

  raw-x-min:
    type: int
    description: |
      Signed raw X axis start for scaling the reported coordinates.
      No effect if screen size is not set.

  raw-y-min:
    type: int
    description: |
      Signed raw Y axis start for scaling the reported coordinates.
      No effect if screen size is not set.

  raw-x-max:
    type: int
    description: |
      Raw X axis end for scaling the reported coordinates.
      No effect if screen size is not set.

  raw-y-max:
    type: int
    description: |
      Raw Y axis end for scaling the reported coordinates.
      No effect if screen size is not set.

  panel-driver-settling-time-us:
    type: int
    enum:
      - 10
      - 100
      - 500
      - 1000
      - 5000
      - 10000
      - 50000
      - 100000
    required: true
    description: |
      Panel driver settling time (microseconds). For large panels (> 6"), a capacitor of 10 nF
      is recommended at the touchscreen terminals for noise filtering.
      As a general rule, 1-5 nF capacitors require around 500 us settling time, and 5-10 nF need
      around 1 ms. When a larger capacitor is used, this value should be changed, as it can
      lead to inaccuracy of the measurement.

  touch-detect-delay-us:
    type: int
    enum:
      - 10
      - 50
      - 100
      - 500
      - 1000
      - 5000
      - 10000
      - 50000
    required: true
    description: |
      Touch detect delay (microseconds) is the delay from the activation of the pull-up resistor
      in the X+ line to the time the device performs touch detection.
      If no capacitor, or a smaller capacitor is used, this value can be lowered to
      minimize detection latency, but it could lower the position stability.

  touch-average-control:
    type: int
    enum:
      - 1
      - 2
      - 4
      - 8
    required: true
    description: |
      Average control (number of samples).
      This parameter can be set to any of the possible values.
      Higher values result in more filtering of noise, but also introduce
      more latency in the touch detection process.

      Use cases that require low touch detection latency
      may benefit from using a lower value for this parameter,
      at the cost of less noise filtering.

  tracking-index:
    type: int
    enum:
      - 0
      - 4
      - 8
      - 16
      - 32
      - 64
      - 92
      - 127
    required: true
    description: |
      Tracking index determines the minimal distance between
      the current touch position and the previous touch position.
      If the distance is shorter than the tracking index, it is discarded.
      Lowering the tracking index increases the frequency of touch events,
      but also increases the load on the system.