Tom Rini | 53633a8 | 2024-02-29 12:33:36 -0500 | [diff] [blame] | 1 | # SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) |
| 2 | %YAML 1.2 |
| 3 | --- |
| 4 | $id: http://devicetree.org/schemas/auxdisplay/hit,hd44780.yaml# |
| 5 | $schema: http://devicetree.org/meta-schemas/core.yaml# |
| 6 | |
| 7 | title: Hitachi HD44780 Character LCD Controller |
| 8 | |
| 9 | maintainers: |
| 10 | - Geert Uytterhoeven <geert@linux-m68k.org> |
| 11 | |
| 12 | description: |
| 13 | The Hitachi HD44780 Character LCD Controller is commonly used on character |
| 14 | LCDs that can display one or more lines of text. It exposes an M6800 bus |
| 15 | interface, which can be used in either 4-bit or 8-bit mode. By using a |
| 16 | GPIO expander it is possible to use the driver with one of the popular I2C |
| 17 | expander boards based on the PCF8574 available for these displays. For |
| 18 | an example see below. |
| 19 | |
| 20 | properties: |
| 21 | compatible: |
| 22 | const: hit,hd44780 |
| 23 | |
| 24 | data-gpios: |
| 25 | description: |
| 26 | GPIO pins connected to the data signal lines DB0-DB7 (8-bit mode) or |
| 27 | DB4-DB7 (4-bit mode) of the LCD Controller's bus interface. |
| 28 | oneOf: |
| 29 | - maxItems: 4 |
| 30 | - maxItems: 8 |
| 31 | |
| 32 | enable-gpios: |
| 33 | description: |
| 34 | GPIO pin connected to the "E" (Enable) signal line of the LCD |
| 35 | Controller's bus interface. |
| 36 | maxItems: 1 |
| 37 | |
| 38 | rs-gpios: |
| 39 | description: |
| 40 | GPIO pin connected to the "RS" (Register Select) signal line of the LCD |
| 41 | Controller's bus interface. |
| 42 | maxItems: 1 |
| 43 | |
| 44 | rw-gpios: |
| 45 | description: |
| 46 | GPIO pin connected to the "RW" (Read/Write) signal line of the LCD |
| 47 | Controller's bus interface. |
| 48 | maxItems: 1 |
| 49 | |
| 50 | backlight-gpios: |
| 51 | description: GPIO pin used for enabling the LCD's backlight. |
| 52 | maxItems: 1 |
| 53 | |
| 54 | display-height-chars: |
| 55 | description: Height of the display, in character cells, |
| 56 | $ref: /schemas/types.yaml#/definitions/uint32 |
| 57 | minimum: 1 |
| 58 | maximum: 4 |
| 59 | |
| 60 | display-width-chars: |
| 61 | description: Width of the display, in character cells. |
| 62 | $ref: /schemas/types.yaml#/definitions/uint32 |
| 63 | minimum: 1 |
| 64 | maximum: 64 |
| 65 | |
| 66 | internal-buffer-width: |
| 67 | description: |
| 68 | Internal buffer width (default is 40 for displays with 1 or 2 lines, and |
| 69 | display-width-chars for displays with more than 2 lines). |
| 70 | $ref: /schemas/types.yaml#/definitions/uint32 |
| 71 | minimum: 1 |
| 72 | maximum: 64 |
| 73 | |
| 74 | required: |
| 75 | - compatible |
| 76 | - data-gpios |
| 77 | - enable-gpios |
| 78 | - rs-gpios |
| 79 | - display-height-chars |
| 80 | - display-width-chars |
| 81 | |
| 82 | additionalProperties: false |
| 83 | |
| 84 | examples: |
| 85 | - | |
| 86 | #include <dt-bindings/gpio/gpio.h> |
Tom Rini | 6bb92fc | 2024-05-20 09:54:58 -0600 | [diff] [blame] | 87 | display-controller { |
| 88 | compatible = "hit,hd44780"; |
Tom Rini | 53633a8 | 2024-02-29 12:33:36 -0500 | [diff] [blame] | 89 | |
Tom Rini | 6bb92fc | 2024-05-20 09:54:58 -0600 | [diff] [blame] | 90 | data-gpios = <&hc595 0 GPIO_ACTIVE_HIGH>, |
| 91 | <&hc595 1 GPIO_ACTIVE_HIGH>, |
| 92 | <&hc595 2 GPIO_ACTIVE_HIGH>, |
| 93 | <&hc595 3 GPIO_ACTIVE_HIGH>; |
| 94 | enable-gpios = <&hc595 4 GPIO_ACTIVE_HIGH>; |
| 95 | rs-gpios = <&hc595 5 GPIO_ACTIVE_HIGH>; |
Tom Rini | 53633a8 | 2024-02-29 12:33:36 -0500 | [diff] [blame] | 96 | |
Tom Rini | 6bb92fc | 2024-05-20 09:54:58 -0600 | [diff] [blame] | 97 | display-height-chars = <2>; |
| 98 | display-width-chars = <16>; |
Tom Rini | 53633a8 | 2024-02-29 12:33:36 -0500 | [diff] [blame] | 99 | }; |
Tom Rini | 6bb92fc | 2024-05-20 09:54:58 -0600 | [diff] [blame] | 100 | |
Tom Rini | 53633a8 | 2024-02-29 12:33:36 -0500 | [diff] [blame] | 101 | - | |
| 102 | #include <dt-bindings/gpio/gpio.h> |
| 103 | i2c { |
Tom Rini | 6bb92fc | 2024-05-20 09:54:58 -0600 | [diff] [blame] | 104 | #address-cells = <1>; |
| 105 | #size-cells = <0>; |
Tom Rini | 53633a8 | 2024-02-29 12:33:36 -0500 | [diff] [blame] | 106 | |
Tom Rini | 6bb92fc | 2024-05-20 09:54:58 -0600 | [diff] [blame] | 107 | pcf8574: gpio-expander@27 { |
| 108 | compatible = "nxp,pcf8574"; |
| 109 | reg = <0x27>; |
| 110 | gpio-controller; |
| 111 | #gpio-cells = <2>; |
| 112 | }; |
Tom Rini | 53633a8 | 2024-02-29 12:33:36 -0500 | [diff] [blame] | 113 | }; |
Tom Rini | 6bb92fc | 2024-05-20 09:54:58 -0600 | [diff] [blame] | 114 | |
| 115 | display-controller { |
| 116 | compatible = "hit,hd44780"; |
| 117 | display-height-chars = <2>; |
| 118 | display-width-chars = <16>; |
| 119 | data-gpios = <&pcf8574 4 GPIO_ACTIVE_HIGH>, |
| 120 | <&pcf8574 5 GPIO_ACTIVE_HIGH>, |
| 121 | <&pcf8574 6 GPIO_ACTIVE_HIGH>, |
| 122 | <&pcf8574 7 GPIO_ACTIVE_HIGH>; |
| 123 | enable-gpios = <&pcf8574 2 GPIO_ACTIVE_HIGH>; |
| 124 | rs-gpios = <&pcf8574 0 GPIO_ACTIVE_HIGH>; |
| 125 | rw-gpios = <&pcf8574 1 GPIO_ACTIVE_HIGH>; |
| 126 | backlight-gpios = <&pcf8574 3 GPIO_ACTIVE_HIGH>; |
Tom Rini | 53633a8 | 2024-02-29 12:33:36 -0500 | [diff] [blame] | 127 | }; |