Create README

README.md

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+# eink-feed
+
+A lightweight system for delivering dynamic images to eInk display (like Kindles) over a WebSocket-based protocol.
+It enables remote rendering and real-time updates for information displays.
+
+## eink-feed-server
+
+```
+eink-feed-server
+    -h, --help
+            Display this help and exit.
+
+        --port <u16>
+            Web server port.
+
+        --config <str>
+            Path to config file.
+```
+
+### API
+
+- `GET /api/channel?id=<CHANNEL_ID>`:
+  Returns channel configuration. Can be used by a rendering server to get display information about the image channel.
+- `POST /api/frame?id=<CHANNEL_ID>&orientation=<(portrait|landscape)_(left|right)>`:
+  Accepts a multipart form with a BMP or PNG.
+- `/api/ws/display`:
+  WebSocket endpoint for protobuf communication between a display client and the server. Image data is sent over this socket.
+
+### Configuration
+
+```json
+{
+  "channels": [
+    {
+      "id": 1,
+      "name": "test-channel",
+      "display": {
+        "width": 800,
+        "height": 600,
+        "orientation": "landscape_left"
+      }
+    }
+  ],
+  "clients": [
+    {
+      "name": "test-kindle",
+      "channel_id": 1
+    }
+  ]
+}
+```
+
+## eink-feed-client
+
+Currently only runs on a Kindle 4/5 (https://git.dergrimm.net/dergrimm/kindle)
+
+```
+eink-feed-client
+    -h, --help
+            Display this help and exit.
+
+        --host <str>
+            eink-feed server host (e.g. hostname:port).
+
+        --name <str>
+            Client name.
+
+        --partial
+            Enable partial eink framebuffer updates. May not look as sharp but reduces flickering.
+```
+
+## eink-feed-render-departures
+
+Render implementation that displays departure information of a public transit stop using an EFA-JSON endpoint.
+
+```
+eink-feed-render-departures
+    -h, --help
+            Display this help and exit.
+
+        --url <str>
+            URL of eink-feed server.
+
+        --channel <u32>
+            Channel ID.
+
+        --efa <str>
+            URL of EFA server.
+
+        --stop <str>
+            Stop ID.
+
+        --tz <str>
+            Time zone.
+
+        --max <usize>
+            Max number of departures listed.
+
+        --show-operator
+            Show operator.
+
+        --stopfinder <str>
+            Search for stops on the EFA server with the given search query.
+```
+
+<hr />
+
+Search for stops:
+
+`eink-feed-render-departures --efa 'https://example.com' --stopfinder 'Stuttgart' | jq`
+
+<hr />
+
+Render departures for a stop ID:
+
+`eink-feed-render-departures --url 'http://<HOST>:<PORT>' --channel <CHANNEL_ID> --efa 'https://example.com' --tz 'Europe/Berlin' --show-operator --stop 'de:08111:6115'`
+
+<hr />
+
+![Photo of a Kindle with train departures](assets/departures.jpg)