126 lines
3.5 KiB
YAML
126 lines
3.5 KiB
YAML
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# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
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%YAML 1.2
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---
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$id: http://devicetree.org/schemas/auxdisplay/hit,hd44780.yaml#
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$schema: http://devicetree.org/meta-schemas/core.yaml#
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title: Hitachi HD44780 Character LCD Controller
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maintainers:
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- Geert Uytterhoeven <geert@linux-m68k.org>
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description:
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The Hitachi HD44780 Character LCD Controller is commonly used on character
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LCDs that can display one or more lines of text. It exposes an M6800 bus
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interface, which can be used in either 4-bit or 8-bit mode. By using a
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GPIO expander it is possible to use the driver with one of the popular I2C
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expander boards based on the PCF8574 available for these displays. For
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an example see below.
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properties:
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compatible:
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const: hit,hd44780
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data-gpios:
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description:
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GPIO pins connected to the data signal lines DB0-DB7 (8-bit mode) or
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DB4-DB7 (4-bit mode) of the LCD Controller's bus interface.
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oneOf:
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- maxItems: 4
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- maxItems: 8
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enable-gpios:
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description:
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GPIO pin connected to the "E" (Enable) signal line of the LCD
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Controller's bus interface.
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maxItems: 1
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rs-gpios:
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description:
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GPIO pin connected to the "RS" (Register Select) signal line of the LCD
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Controller's bus interface.
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maxItems: 1
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rw-gpios:
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description:
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GPIO pin connected to the "RW" (Read/Write) signal line of the LCD
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Controller's bus interface.
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maxItems: 1
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backlight-gpios:
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description: GPIO pin used for enabling the LCD's backlight.
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maxItems: 1
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display-height-chars:
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description: Height of the display, in character cells,
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$ref: /schemas/types.yaml#/definitions/uint32
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minimum: 1
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maximum: 4
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display-width-chars:
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description: Width of the display, in character cells.
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$ref: /schemas/types.yaml#/definitions/uint32
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minimum: 1
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maximum: 64
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internal-buffer-width:
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description:
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Internal buffer width (default is 40 for displays with 1 or 2 lines, and
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display-width-chars for displays with more than 2 lines).
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$ref: /schemas/types.yaml#/definitions/uint32
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minimum: 1
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maximum: 64
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required:
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- compatible
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- data-gpios
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- enable-gpios
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- rs-gpios
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- display-height-chars
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- display-width-chars
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additionalProperties: false
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examples:
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- |
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#include <dt-bindings/gpio/gpio.h>
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auxdisplay {
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compatible = "hit,hd44780";
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data-gpios = <&hc595 0 GPIO_ACTIVE_HIGH>,
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<&hc595 1 GPIO_ACTIVE_HIGH>,
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<&hc595 2 GPIO_ACTIVE_HIGH>,
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<&hc595 3 GPIO_ACTIVE_HIGH>;
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enable-gpios = <&hc595 4 GPIO_ACTIVE_HIGH>;
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rs-gpios = <&hc595 5 GPIO_ACTIVE_HIGH>;
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display-height-chars = <2>;
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display-width-chars = <16>;
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};
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- |
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#include <dt-bindings/gpio/gpio.h>
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i2c {
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#address-cells = <1>;
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#size-cells = <0>;
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pcf8574: pcf8574@27 {
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compatible = "nxp,pcf8574";
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reg = <0x27>;
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gpio-controller;
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#gpio-cells = <2>;
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};
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};
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hd44780 {
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compatible = "hit,hd44780";
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display-height-chars = <2>;
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display-width-chars = <16>;
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data-gpios = <&pcf8574 4 0>,
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<&pcf8574 5 0>,
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<&pcf8574 6 0>,
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<&pcf8574 7 0>;
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enable-gpios = <&pcf8574 2 0>;
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rs-gpios = <&pcf8574 0 0>;
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rw-gpios = <&pcf8574 1 0>;
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backlight-gpios = <&pcf8574 3 0>;
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};
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