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Merge pull request #2453 from esphome/nagyrobi-patch-3
Update lcd_display.rst
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H. Árkosi Róbert
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@ -13,8 +13,9 @@ with ESPHome. This integration is only for LCD displays that display individual
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Mltiple versions of the display exist, supporting different character sets:
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- HD44780UA00 English-Japanese which includes katakana characters and some Greek letters and mathematical symbols
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- HD44780UA00 English-Japanese which includes katakana characters, some Greek letters and mathematical symbols
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- HD44780UA02 English-European which includes Greek, Cyrillic and Western European characters (with some diacritics)
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- HD44780UBxx custom, manufacturer-specific character sets
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It is possible to add 8 user-defined characters too.
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@ -23,9 +24,9 @@ with ESPHome. This integration is only for LCD displays that display individual
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lcd_pcf8574 Component
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---------------------
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``lcd_pcf8574`` is for LCD displays with a PCF8574 connected to all the data pins. This has the benefit that you
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only need to connect two data wires to the ESP instead of the 6 or 10 with the :ref:`lcd-gpio`.
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As the communication with the :ref:`I²C Bus <i2c>`, you need to have an ``i2c:`` section in your configuration.
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``lcd_pcf8574`` is for LCD displays with a PCF8574 GPIO expander module connected to all the data pins. This has the
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benefit that you only need to connect two data wires to the ESP instead of the six or ten as with the :ref:`lcd-gpio`.
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The communication happens via :ref:`I²C Bus <i2c>`, you need to have an ``i2c:`` section in your configuration.
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.. figure:: images/lcd-pcf8574.jpg
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:align: center
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@ -46,8 +47,8 @@ As the communication with the :ref:`I²C Bus <i2c>`, you need to have an ``i2c:`
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display:
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- platform: lcd_pcf8574
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dimensions: 18x4
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address: 0x3F
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dimensions: 20x4
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address: 0x27
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lambda: |-
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it.print("Hello World!");
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@ -82,7 +83,7 @@ faster refresh, especially in conjunction with an :ref:`LCD menu <lcd_menu>`.
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# Example configuration entry
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display:
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- platform: lcd_gpio
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dimensions: 18x4
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dimensions: 20x4
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data_pins:
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- D0
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- D1
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@ -163,20 +164,62 @@ by default which means the character at the top left.
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Please see :ref:`display-printf` for a quick introduction into the ``printf`` formatting rules and
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:ref:`display-strftime` for an introduction into the ``strftime`` time formatting.
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User Defined Characters
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-----------------------
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The LCD display has the possibility to define up to eight user defined characters occupying the characters
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``0`` to ``7`` and mirrored at ``8`` to ``15`` (i.e. ``\x08`` can be used instead of the ``\0`` that can
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be problematic in strings). Each character has eight lines of five bits, with the first line on the top
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and the most significant bit on the left, meaning that ``0b10000`` followed by six zeros and a ``0b00001``
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defines a dot at the upper left and lower right of the character.
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.. code-block:: yaml
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display:
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- platform: lcd_pcf8574
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id: mydisplay
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# ...
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user_characters:
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- position: 0
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data:
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- 0b00000
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- 0b01010
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- 0b00000
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- 0b00100
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- 0b00100
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- 0b10001
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- 0b01110
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- 0b00000
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- position: 7
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data:
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- 0b00000
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- 0b01010
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- 0b00000
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- 0b00100
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- 0b00100
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- 0b00000
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- 0b01110
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- 0b10001
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lambda: |-
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it.print("Hello, world \x08 \x07!");
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Try this `custom Character Generator <https://omerk.github.io/lcdchargen/>`__ to design your own sybmols.
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Backlight Control
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-----------------
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For the GPIO based display, the backlight is lit by applying Vcc to the A pin and K connected to ground.
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The backlight can draw more power than the microcontroller output pins can supply, so it is advisable to use
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a transistor as a switch to control the power for the backlight pins.
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With the ``lcd_pcf8574`` the backlight can be turned on by ``it.backlight()`` and off by ``it.no_backlight()`` in the
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display lambda definition. The jumper on the PCF8574 board needs to be closed for the backlight control to work.
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Keep in mind that the display lambda runs for every ``update_interval``, so if the backlight is turned on/off there,
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it cannot be overridden from other parts.
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Here is one solution for a typical use-case where the backlight is turned on after a motion sensor activates and
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turns off 90 seconds after the last activation of the sensor.
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With the ``lcd_gpio``, the backlight is lit by applying ``Vcc`` to the ``A`` pin and connect ``K`` pin to ``GND``.
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The backlight can draw more power than the microcontroller output pins can supply, so it is advisable to use
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a transistor as a switch to control the power for the backlight pins.
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Below an example for a typical use-case where the backlight is turned on when a motion sensor activates and
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turns off ``90`` seconds after the last activation of the sensor.
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.. code-block:: yaml
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@ -209,44 +252,6 @@ turns off 90 seconds after the last activation of the sensor.
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- lambda: |-
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id(mydisplay).no_backlight();
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User Defined Characters
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-----------------------
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The LCD display has the possibility to define up to eight user defined characters occupying the characters
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``0`` to ``7`` and mirrored at ``8`` to ``15`` (i.e. ``\x08`` can be used instead of the ``\0`` that can
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be problematic in strings). Each character has eight lines of five bits, with the first line on the top
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and the most significant bit on the left, meaning that ``0b10000`` followed by six zeros and a ``0b00001``
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defines a dot at the upper left and lower right of the character.
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.. code-block:: yaml
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display:
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- platform: lcd_pcf8574
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id: mydisplay
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# ...
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user_characters:
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- position: 0
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data:
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- 0b00000
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- 0b01010
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- 0b00000
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- 0b00100
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- 0b00100
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- 0b10001
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- 0b01110
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- 0b00000
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- position: 7
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data:
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- 0b00000
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- 0b01010
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- 0b00000
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- 0b00100
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- 0b00100
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- 0b00000
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- 0b01110
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- 0b10001
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lambda: |-
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it.print("Hello, world \x08 \x07!");
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See Also
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--------
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@ -258,6 +263,7 @@ See Also
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- :doc:`/components/pcf8574`
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- `HD44780U (LCD-II) datasheet <https://www.sparkfun.com/datasheets/LCD/HD44780.pdf>`__
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- `Charset cheatsheet <https://user-images.githubusercontent.com/1550668/173113487-9c98e866-8ee4-4a3c-a83f-61fe62057c5f.png>`__
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- `Custom Character Generator <https://omerk.github.io/lcdchargen/>`__
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- `Arduino LiquidCrystal Library <https://www.arduino.cc/en/Reference/LiquidCrystal>`__
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- :apiref:`lcd_base/lcd_display.h`
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- :ghedit:`Edit`
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