improve instructions

README.md

@@ -7,3 +7,20 @@ Perhaps useful if you have a stationary bike of some kind and want to
 put the vital statistics on a big screen instead of on your handlebar.
 
 ![screenshot](20221209_22h46m07s_grim.png)
+
+## How to use
+
+First you need to identify bluetooth address of your bike sensor(s).
+Spin the wheel to wake it up, then run
+
+```sh
+$ bluetoothctl scan on
+Discovery started
+[CHG] Controller 24:FD:52:00:ED:F1 Discovering: yes
+[NEW] Device C2:35:5D:F2:F4:0F  Giant Combo
+[CHG] Device 98:06:3A:15:B7:BA RSSI: -82
+^C
+$ bluetoothctl connect  C2:35:5D:F2:F4:0F
+```
+
+Now 

csc.py

@@ -111,9 +111,7 @@ class Biscuit:
         pygame.display.flip()
 
 
-
-bike_address = 'C2:35:5D:F2:F4:0F'
-bike = BLE_GATT.Central(bike_address)
+bike = BLE_GATT.Central(sys.argv[1])
 bike.connect()
 app = Biscuit()