update readme

README.md

@@ -2,6 +2,26 @@
 This is eventually gonna be a kernel module capable of sending text to a connected LCD display.
 The communication would be happening via device file `/dev/lcd`
 
+Installing the module creates the device `/dev/lcd` used for sending text to the screen. The LCD display
+is turned on by opening the file for writing. A string of characters has to be ended with `\n` in order to
+appear on the display.
+
+This is the circuit I used to drive my screen:
+![Circuit Diagram](./img/circuit.svg)
+
+This is also the default pin layout used by the driver. If you want to use a different pin layout, you can change the driver's config as such:
+
+    sudo ./install.sh pin_name=pin_number ...
+
+where `pin_name` is one of the following:
+ * `pin_power`
+ * `pin_rs`
+ * `pin_rw`
+ * `pin_enable`
+ * `pin_data`
+
+and `pin_number` is the GPIO pin number. For `pin_data` you need to supply a comma-separated list of four numbers.
+
 ## How to build
 Good luck.