Add date platform to KNX (#28307)

source/_integrations/knx.markdown

@@ -7,6 +7,7 @@ ha_category:
   - Button
   - Climate
   - Cover
+  - Date
   - Fan
   - Hub
   - Light
@@ -32,6 +33,7 @@ ha_platforms:
   - button
   - climate
   - cover
+  - date
   - diagnostics
   - fan
   - light
@@ -58,6 +60,7 @@ There is currently support for the following device types within Home Assistant:
 - [Button](#button)
 - [Climate](#climate)
 - [Cover](#cover)
+- [Date](#date)
 - [Fan](#fan)
 - [Light](#light)
 - [Notify](#notify)
@@ -904,6 +907,76 @@ entity_category:
   default: None
 {% endconfiguration %}
 
+## Date
+
+The KNX date platform allows to send date values to the KNX bus and update its state from received telegrams. It can optionally respond to read requests from the KNX bus.
+
+<div class='note'>
+
+Date entities without a `state_address` will restore their last known state after Home Assistant was restarted.
+
+Dates that have a `state_address` configured request their current state from the KNX bus.
+
+</div>
+
+<div class='note'>
+
+DPT 11.001 covers the range 1990 to 2089. Year values outside of this range are not allowed.
+
+</div>
+
+```yaml
+# Example configuration.yaml entry
+knx:
+  date:
+    - name: "Date"
+      address: "0/0/2"
+      state_address: "0/0/2"
+```
+
+{% configuration %}
+name:
+  description: A name for this device used within Home Assistant.
+  required: false
+  type: string
+address:
+  description: The group address to which new values will be sent. *DPT 11.001*
+  required: true
+  type: [string, list]
+state_address:
+  description: Group address for retrieving the state from the KNX bus. *DPT 11.001*
+  required: false
+  type: [string, list]
+respond_to_read:
+  description: Respond to GroupValueRead telegrams received to the configured `address`.
+  required: false
+  type: boolean
+  default: false
+sync_state:
+  description: Actively read the value from the bus. The maximum time interval (`<minutes>`) is 1440. The following values are valid
+
+    - `true` equivalent to "expire 60" (default)
+
+    - `false` no GroupValueRead telegrams will be sent to the bus
+
+    - `every <minutes>` to update it regularly every \<minutes\>
+
+    - `expire <minutes>` to read the state from the KNX bus when no telegram was received for \<minutes\>
+
+    - `<minutes>` equivalent to "expire \<minutes\>"
+
+    - `init` to just initialize the state on startup
+
+  required: false
+  type: [boolean, string, integer]
+  default: true
+entity_category:
+  description: The [category](https://developers.home-assistant.io/docs/core/entity#generic-properties) of the entity.
+  required: false
+  type: string
+  default: None
+{% endconfiguration %}
+
 ## Fan
 
 The KNX fan integration is used to control KNX fans. Following control types are supported: