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