Update ble_midi_simpletest.py

* Wait until the BLE connection is paired before sending messages
* Increase the time delay between pairing and sending

examples/ble_midi_simpletest.py

@@ -37,10 +37,16 @@ while True:
     print("Waiting for connection")
     while not ble.connected:
         pass
-    print("Connected")
+    print("Connected; waiting for pairing")
+    for connection in ble.connections:
+        while not connection.paired:
+            if not connection.connected:
+                break
+    if connection.paired:
+        print("Paired; sending MIDI messages")
         # Sleep briefly so client can get ready and send setup
         # writes to the MIDIService. 0.5secs was insufficient.
-    time.sleep(1.0)
+        time.sleep(3.0)
         # Send one unique NoteOn/Off at the beginning to check that the
         # delay is sufficient.
         midi.send(NoteOn(20, 99))