Commit c784e46c authored by Ralf Schlatterbeck's avatar Ralf Schlatterbeck Committed by Miguel Ojeda
Browse files

auxdisplay: Add I2C gpio expander example 



The hd44780 displays are often used with pcf8574 based I/O expanders.
Add example to documentation.

Suggested-by: default avatarGeert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: default avatarRalf Schlatterbeck <rsc@runtux.com>
[Added Suggested-by tag]
Signed-off-by: default avatarMiguel Ojeda <ojeda@kernel.org>
parent 614124be

Documentation/devicetree/bindings/auxdisplay/hit,hd44780.yaml

+30 −1
Original line number Diff line number Diff line
@@ -12,7 +12,10 @@ maintainers: 
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.

  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:
@@ -94,3 +97,29 @@ examples: 
            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>;

    };