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197 lines
7.4 KiB
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197 lines
7.4 KiB
ReStructuredText
XPT2046 Touch Screen Controller (Updated version)
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==================================================
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.. seo::
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:description: Instructions for setting up XPT2046 touch screen controller with ESPHome
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:image: xpt2046.jpg
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:keywords: XPT2046
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.. _xpt2046-component:
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The ``xpt2046`` touchscreen platform allows using the touch screen controllers
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based on the XPT2046 chip
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(`datasheet <https://datasheetspdf.com/pdf-file/746665/XPTEK/XPT2046/1>`__,
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`AZ-Delivery`_) with ESPHome. Many cheap LCD displays contain this controller.
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The :ref:`SPI <spi>` is required to be set up in your configuration for this sensor to work.
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.. figure:: images/xpt2046-full.jpg
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:align: center
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:width: 50.0%
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XPT2046 Touch Screen Controller
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.. _AZ-Delivery: https://www.az-delivery.de/en/products/2-4-tft-lcd-touch-display
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.. code-block:: yaml
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# Example configuration entry
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touchscreen:
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platform: xpt2046
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id: my_touchscreen
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cs_pin: 17
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interrupt_pin: 16
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update_interval: 50ms
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report_interval: 1s
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threshold: 400
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calibration_x_min: 3860
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calibration_x_max: 280
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calibration_y_min: 340
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calibration_y_max: 3860
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swap_x_y: false
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Configuration variables:
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------------------------
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The configuration is made up of two parts: The touch screen component, and optional individual binary sensors.
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Base Configuration:
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- **id** (*Optional*, :ref:`config-id`): Set the ID of this sensor.
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- **cs_pin** (*Optional*, :ref:`Pin Schema <config-pin_schema>`): The chip select pin.
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Often marked ``T_CS`` on the board.
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- **interrupt_pin** (*Optional*, :ref:`Pin Schema <config-pin_schema>`): The touch detection pin.
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Often marked ``T_IRQ`` on the board. If not specified the component will use polling
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via SPI. This key is renamed from **irq_pin**
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- **update_interval** (*Optional*, :ref:`config-time`): The interval to check the
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sensor. If ``interrupt_pin`` is specified the touch will be detected nearly instantaneously and this setting
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will be used only for the release detection. Defaults to ``50ms``.
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- **report_interval** (*Optional*, :ref:`config-time`): The interval to periodically
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report the coordinates while the touch screen is touched. Defaults to ``never``.
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- **threshold** (*Optional*, int): The value to detect the touch or release. Defaults to ``400``.
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- **calibration_x_min** (*Optional*, int): The raw value corresponding to the left
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(or top if ``swap_x_y`` is specified) edge of the display. See :ref:`xpt2046-calibration`
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for the process to calibrate the touch screen. Defaults to ``0``.
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- **calibration_x_max** (*Optional*, int): The raw value corresponding to the right
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(or bottom if ``swap_x_y`` is specified) edge of the display. Defaults to ``4095``.
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- **calibration_y_min** (*Optional*, int): The raw value corresponding to the top
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(or left if ``swap_x_y`` is specified) edge of the display. Defaults to ``0``.
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- **calibration_y_max** (*Optional*, int): The raw value corresponding to the bottom
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(or right if ``swap_x_y`` is specified) edge of the display. Defaults to ``4095``.
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- **swap_x_y** (*Optional*, boolean): If true the x and y axes are swapped. Defaults to ``false``.
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- All other options from :ref:`config-touchscreen`.
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.. _xpt2046-calibration:
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Calibration
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-----------
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To match the point of the touch to the display coordinates the touch screen has to be calibrated.
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The XPT2046 component returns raw values in the 0 to 4095 range. Those raw values are available
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as the ``x_raw`` and ``y_raw`` member variables and for example write them out as in the example
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:ref:`touchscreen-on_touch`. The goal of the calibration is to identify the raw values corresponding
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to the edges of the screen.
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The calibration assumes a display oriented in a way that you will be using it, i.e. your
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:ref:`display-engine` component has to have the [0,0] logical coordinate at the top left.
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Set the dimensions as ``dimension_x`` and ``dimension_y`` and do not set any calibration
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values nor ``swap_x_y``.
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.. code-block:: yaml
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# Touchscreen
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touchscreen:
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platform: xpt2046
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id: my_touchscreen
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cs_pin: 17
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on_touch:
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- lambda: |-
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ESP_LOGI("cal", "x=%d, y=%d, x_raw=%d, y_raw=%0d",
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id(my_touchscreen).x,
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id(my_touchscreen).y,
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id(my_touchscreen).x_raw,
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id(my_touchscreen).y_raw
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);
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Get a stylus or a similar object, run the project and touch the corners of the screen at
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the edge pixels. Repeat several times and note minimum and maximum x and y raw values.
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.. code-block:: none
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... top left ...
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[21:07:48][I][cal:071]: x=217, y=34, x_raw=3718, y_raw=445
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[21:07:49][I][cal:071]: x=222, y=32, x_raw=3804, y_raw=419
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... top right ...
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[21:07:52][I][cal:071]: x=19, y=36, x_raw=334, y_raw=370
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[21:07:52][I][cal:071]: x=22, y=35, x_raw=386, y_raw=347
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... bottom left ...
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[21:08:00][I][cal:071]: x=224, y=299, x_raw=3836, y_raw=3835
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[21:08:00][I][cal:071]: x=225, y=303, x_raw=3848, y_raw=3878
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[21:08:01][I][cal:071]: x=223, y=299, x_raw=3807, y_raw=3829
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... bottom right ...
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[21:08:11][I][cal:071]: x=16, y=299, x_raw=281, y_raw=3839
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[21:08:12][I][cal:071]: x=19, y=302, x_raw=328, y_raw=3866
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[21:08:13][I][cal:071]: x=20, y=296, x_raw=358, y_raw=3799
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That means that the minimum raw x is 281, maximum 3848, minimum y 347 and maximum 3878.
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Identify which raw value is the display's x direction and what the y one. In our case
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moving right decreases the x raw value and going down increases the y one so the axes
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match and we *don't* need to use ``swap_x_y``. If the raw x is the display's y,
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use ``swap_x_y = true``.
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If one of the coordinates goes in the "wrong" direction it needs to be inverted.
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The inversion is performed by swapping the minimum and maximum values. In our
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case the horizontal direction represented by the raw x (no swap) is inverted
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so the ``calibration_x_min`` needs to be larger than ``calibration_x_max``.
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The vertical direction is fine. The configuration would thus be
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.. code-block:: yaml
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touchscreen:
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platform: xpt2046
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calibration_x_min: 3848
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calibration_x_max: 281
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calibration_y_min: 347
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calibration_y_max: 3878
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Compile, run and click on the edges again. The x and y should now match the coordinates
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of the display.
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.. code-block:: none
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[21:32:34][I][cal:071]: x=7, y=6, x_raw=3755, y_raw=407
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[21:32:37][I][cal:071]: x=237, y=4, x_raw=313, y_raw=385
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[21:32:43][I][cal:071]: x=239, y=318, x_raw=284, y_raw=3845
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[21:33:05][I][cal:071]: x=2, y=313, x_raw=3821, y_raw=3793
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Note that the touch screen is not extremely precise and there might be nonlinearities
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or similar errors so don't expect a pixel-perfect precision. You can verify the touchpoint
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using a display lambda similar to the following.
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.. code-block:: yaml
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display:
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- platform: ili9341
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lambda: |-
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it.fill(BLACK);
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if (id(my_touchscreen).touched)
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it.filled_circle(id(my_touchscreen).x, id(my_touchscreen).y, 10, RED);
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To be exact, the component does the following
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- reads the raw x and y and normalizes it using (non-inverted) min and max values
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- swaps x and y if needed
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- inverts if needed
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- scales to the display dimensions
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See Also
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--------
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- :ref:`Binary Sensor Filters <binary_sensor-filters>`
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- :apiref:`xpt2046/xpt2046.h`
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- `XPT2046 Library <https://platformio.org/lib/show/542/XPT2046_Touchscreen>`__ by `Paul Stoffregen <https://github.com/PaulStoffregen>`__
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- :ghedit:`Edit`
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