Create orangepi_gpio.markdown (#9072)

* Create orangepi_gpio.markdown

* Correct sysfs-gpio version

* Remove cover platform

As the parent removed the cover component for now, reflect this in documentation as well.

* Limit ourselves to one platform for now

source/_components/orangepi_gpio.markdown

@@ -0,0 +1,85 @@
+---
+layout: page
+title: "Orange Pi GPIO"
+description: "Instructions on how to integrate the GPIO capability of a Orange Pi into Home Assistant."
+date: 2019-03-29 19:00
+sidebar: true
+comments: false
+sharing: true
+footer: true
+ha_category:
+  - DIY
+  - Binary Sensor
+ha_release: 0.92
+ha_iot_class: Local Push
+---
+
+The `orangepi_gpio` component is the base for all related GPIO platforms in Home Assistant. There is no setup needed for the component itself, for the platforms please check their corresponding pages.
+
+## {% linkable_title Binary Sensor %}
+
+The `orangepi_gpio` binary sensor platform allows you to read sensor values of the GPIOs of your Orange Pi or NanoPi.
+
+## {% linkable_title Configuration %}
+
+To use your Orange Pi's GPIO in your installation, add the following to your `configuration.yaml` file:
+
+```yaml
+# Example configuration.yaml entry
+binary_sensor:
+  - platform: orangepi_gpio
+    pinmode: pc
+    ports:
+      11: PIR Office
+      12: PIR Bedroom
+```
+
+{% configuration %}
+pinmode:
+  description: Type of pinmode to use. This depends on which device you are actually using it ([PINMODE](/components/orangepi_gpio#pinmode)).
+  required: true
+  type: string
+ports:
+  description: List of used ports.
+  required: true
+  type: map
+  keys:
+    "port: name":
+      description: The port numbers (physical pin numbers) and corresponding names.
+      required: true
+      type: string
+invert_logic:
+  description: If `true`, inverts the output logic to ACTIVE LOW.
+  required: false
+  type: boolean
+  default: "`false` (ACTIVE HIGH)"
+{% endconfiguration %}
+
+Compared to the [Raspberry Pi GPIO](/components/rpi_gpio/) component, this component does not support pull-up resistors or port debouncing. Use external pull-ups and external port-debouncing.
+
+## {% linkable_title Pinmode %}
+
+As this platform supports different types of GPIO pinouts for difference Orange Pi or Nano Pi devices, we use the `pinmode` value to specify which one to use. Enabled values are:
+
+| Value | Description |
+| ----- | ----------- |
+| `pc` | Supports the Orange Pi Lite, One, PC and Prime |
+| `zeroplus` | Supports the Orange Pi Zero Plus |
+| `zeroplus2` | Supports the Orange Pi Zero Plus 2 |
+| `duo` | Supports the NanoPi Duo |
+| `neocore2` | Supports the NanoPi Neocore 2 |
+
+## {% linkable_title Additional steps %}
+This component uses the `SYSFS` filesystem to get control of the GPIOs. Therefore an operatings system with `CONFIG_GPIO_SYSFS` is required. As far as I know, most out-of-the-box distributions still enable this by default.
+
+As of Linux 4.8 sysfs-gpio is marked as obsolete. However as of today, the alternative GPIO character device is not widely used. Therefore we will use this until the new character device is more widely supported.
+
+Normally the `/sys/class/gpio` path is owned by root, so Home Assistant does not have access. As we don't want to run Home Assistant as root, we will add the group `gpio` to have control over this path. I will assume you added the `homeassistant` user already to the `gpio` group as recommended in the [Manual installation guide](/docs/installation/raspberry-pi/)
+
+Create a new file in `/etc/udev/rules.d/` named `10-gpio.rules` with the following contents:
+
+```
+SUBSYSTEM=="gpio*", PROGRAM="/bin/sh -c 'find -L /sys/class/gpio/ -maxdepth 2 -exec chown root:gpio {} \; -exec chmod 770 {} \; || true'"
+```
+
+Home Assistant will now be able to control your GPIO pins.