Update lcd_display.rst

A few more fixes.
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H. Árkosi Róbert 2022-11-17 14:53:26 +01:00 committed by GitHub
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@ -13,8 +13,9 @@ with ESPHome. This integration is only for LCD displays that display individual
Mltiple versions of the display exist, supporting different character sets:
- HD44780UA00 English-Japanese which includes katakana characters and some Greek letters and mathematical symbols
- HD44780UA00 English-Japanese which includes katakana characters, some Greek letters and mathematical symbols
- HD44780UA02 English-European which includes Greek, Cyrillic and Western European characters (with some diacritics)
- HD44780UBxx custom, manufacturer-specific character sets
It is possible to add 8 user-defined characters too.
@ -23,9 +24,9 @@ with ESPHome. This integration is only for LCD displays that display individual
lcd_pcf8574 Component
---------------------
``lcd_pcf8574`` is for LCD displays with a PCF8574 connected to all the data pins. This has the benefit that you
only need to connect two data wires to the ESP instead of the 6 or 10 with the :ref:`lcd-gpio`.
As the communication with the :ref:`I²C Bus <i2c>`, you need to have an ``i2c:`` section in your configuration.
``lcd_pcf8574`` is for LCD displays with a PCF8574 GPIO expander module connected to all the data pins. This has the
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`.
The communication happens via :ref:`I²C Bus <i2c>`, you need to have an ``i2c:`` section in your configuration.
.. figure:: images/lcd-pcf8574.jpg
:align: center
@ -46,8 +47,8 @@ As the communication with the :ref:`I²C Bus <i2c>`, you need to have an ``i2c:`
display:
- platform: lcd_pcf8574
dimensions: 18x4
address: 0x3F
dimensions: 20x4
address: 0x27
lambda: |-
it.print("Hello World!");
@ -82,7 +83,7 @@ faster refresh, especially in conjunction with an :ref:`LCD menu <lcd_menu>`.
# Example configuration entry
display:
- platform: lcd_gpio
dimensions: 18x4
dimensions: 20x4
data_pins:
- D0
- D1
@ -163,20 +164,62 @@ by default which means the character at the top left.
Please see :ref:`display-printf` for a quick introduction into the ``printf`` formatting rules and
:ref:`display-strftime` for an introduction into the ``strftime`` time formatting.
User Defined Characters
-----------------------
The LCD display has the possibility to define up to eight user defined characters occupying the characters
``0`` to ``7`` and mirrored at ``8`` to ``15`` (i.e. ``\x08`` can be used instead of the ``\0`` that can
be problematic in strings). Each character has eight lines of five bits, with the first line on the top
and the most significant bit on the left, meaning that ``0b10000`` followed by six zeros and a ``0b00001``
defines a dot at the upper left and lower right of the character.
.. code-block:: yaml
display:
- platform: lcd_pcf8574
id: mydisplay
# ...
user_characters:
- position: 0
data:
- 0b00000
- 0b01010
- 0b00000
- 0b00100
- 0b00100
- 0b10001
- 0b01110
- 0b00000
- position: 7
data:
- 0b00000
- 0b01010
- 0b00000
- 0b00100
- 0b00100
- 0b00000
- 0b01110
- 0b10001
lambda: |-
it.print("Hello, world \x08 \x07!");
Try this `custom Character Generator <https://omerk.github.io/lcdchargen/>`__ to design your own sybmols.
Backlight Control
-----------------
For the GPIO based display, the backlight is lit by applying Vcc to the A pin and K connected to ground.
The backlight can draw more power than the microcontroller output pins can supply, so it is advisable to use
a transistor as a switch to control the power for the backlight pins.
With the ``lcd_pcf8574`` the backlight can be turned on by ``it.backlight()`` and off by ``it.no_backlight()`` in the
display lambda definition. The jumper on the PCF8574 board needs to be closed for the backlight control to work.
Keep in mind that the display lambda runs for every ``update_interval``, so if the backlight is turned on/off there,
it cannot be overridden from other parts.
Here is one solution for a typical use-case where the backlight is turned on after a motion sensor activates and
turns off 90 seconds after the last activation of the sensor.
With the ``lcd_gpio``, the backlight is lit by applying ``Vcc`` to the ``A`` pin and connect ``K`` pin to ``GND``.
The backlight can draw more power than the microcontroller output pins can supply, so it is advisable to use
a transistor as a switch to control the power for the backlight pins.
Below an example for a typical use-case where the backlight is turned on when a motion sensor activates and
turns off ``90`` seconds after the last activation of the sensor.
.. code-block:: yaml
@ -209,44 +252,6 @@ turns off 90 seconds after the last activation of the sensor.
- lambda: |-
id(mydisplay).no_backlight();
User Defined Characters
-----------------------
The LCD display has the possibility to define up to eight user defined characters occupying the characters
``0`` to ``7`` and mirrored at ``8`` to ``15`` (i.e. ``\x08`` can be used instead of the ``\0`` that can
be problematic in strings). Each character has eight lines of five bits, with the first line on the top
and the most significant bit on the left, meaning that ``0b10000`` followed by six zeros and a ``0b00001``
defines a dot at the upper left and lower right of the character.
.. code-block:: yaml
display:
- platform: lcd_pcf8574
id: mydisplay
# ...
user_characters:
- position: 0
data:
- 0b00000
- 0b01010
- 0b00000
- 0b00100
- 0b00100
- 0b10001
- 0b01110
- 0b00000
- position: 7
data:
- 0b00000
- 0b01010
- 0b00000
- 0b00100
- 0b00100
- 0b00000
- 0b01110
- 0b10001
lambda: |-
it.print("Hello, world \x08 \x07!");
See Also
--------
@ -258,6 +263,7 @@ See Also
- :doc:`/components/pcf8574`
- `HD44780U (LCD-II) datasheet <https://www.sparkfun.com/datasheets/LCD/HD44780.pdf>`__
- `Charset cheatsheet <https://user-images.githubusercontent.com/1550668/173113487-9c98e866-8ee4-4a3c-a83f-61fe62057c5f.png>`__
- `Custom Character Generator <https://omerk.github.io/lcdchargen/>`__
- `Arduino LiquidCrystal Library <https://www.arduino.cc/en/Reference/LiquidCrystal>`__
- :apiref:`lcd_base/lcd_display.h`
- :ghedit:`Edit`