companion/app.py

 from kivy.app import App
+from kivy.clock import mainthread
 from kivy.logger import Logger
 from kivy.properties import ObjectProperty
 from kivy.uix.button import Button
@@ -12,17 +13,30 @@ class DeviceListWidget(Widget):
     def __init__(self, *args, **kwargs):
         super().__init__(*args, **kwargs)
 
-        self._devices_buttons_map = {}
+        self._previous_addresses = {}
 
-    def update_device_buttons(self, devices):
-        Logger.debug("Updating device buttons")
-        self._devices_buttons_map = devices
+    @mainthread
+    def update_device_buttons(self, buttons_map):
+        Logger.info("Updating device buttons")
 
-        self.device_buttons.clear_widgets()
-        for label, device in self._devices_buttons_map.items():
-            Logger.debug("Adding button for %s" % label)
-            btn = Button(text=label)
+        for address, info in buttons_map.items():
+            if address in self._previous_addresses:
+                Logger.info("Button for %s already there, skipping" % address)
+                continue
+
+            label, cb_connect = info
+
+            Logger.info("Adding button for %s (%s)" % (address, label))
+
+            btn = Button(text=label, on_press=cb_connect)
             self.device_buttons.add_widget(btn)
+            self._previous_addresses[address] = btn
+
+        for address in self._previous_addresses:
+            if address not in self._previous_addresses:
+                Logger.info("%s no longer in device list, removing button" % address)
+                self.remove_widget(self._previous_addresses[address])
+                del self._previous_addresses[address]
 
 
 class MynitCompanionApp(App):
@@ -32,4 +46,21 @@ class MynitCompanionApp(App):
         self._bluetooth = MynitBluetooth(self)
 
     def update_device_list(self, devices):
-        self.widget.update_device_buttons({device.getAddress(): device for device in devices})
+        Logger.info("Updating device buttons")
+
+        buttons_map = {}
+        for device in devices:
+            if not device.getName():
+                Logger.info("Device %s skipped due to missing name" % device.getAddress())
+                continue
+
+            def cb_connect(*args, **kwargs):
+                self._bluetooth.set_device(device)
+
+            buttons_map[device.getAddress()] = (device.getName(), cb_connect)
+
+        self.widget.update_device_buttons(buttons_map)
+
+    def build(self):
+        self.widget = DeviceListWidget()
+        return self.widget

companion/bluetooth.py

@@ -16,7 +16,7 @@ class MynitBluetooth(BluetoothDispatcher):
 
         self._app = app
         self._available_devices = set()
-        self._current_device = None
+        self._device = None
         self._characteristics = None, None
 
         Logger.info("Starting BLE scanning")
@@ -24,26 +24,35 @@ class MynitBluetooth(BluetoothDispatcher):
         self.start_scan()
 
     def on_device(self, device, rssi, advertisement):
-        Logger.debug("BLE device discovered: %s" % device.getAddress())
-        self.stop_scan()
+        Logger.info("BLE device discovered: %s" % device.getAddress())
+
         if device not in self._available_devices:
-            Logger.info("New BLE device discovered: %s" % device.getAddress())
+            Logger.info("New BLE device discovered: %s (%s)" % (device.getAddress(), device.getName()))
             self._available_devices.add(device)
 
             self._app.update_device_list(self._available_devices)
 
+    def set_device(self, device):
+        self._device = device
+        self.stop_scan()
+
+    def on_scan_completed(self):
+        if self._device:
+            self.connect_gatt(self._device)
+
     def on_connection_state_change(self, status, state):
-        Logger.debug("Connection state changed")
+        Logger.info("Connection state changed - state: %d, status: %d" % (state, status))
 
-        if status == GATT_SUCCESS and state:
+        if status == GATT_SUCCESS:
             Logger.info("Connection successful, discovering services")
-            self._current_device = device
             self.discover_services()
         else:
             Logger.warning("Connection failed, disconnecting and resetting")
             self.close_gatt()
-            self._current_device = None
             self._characteristics = None, None
+            self._device = None
+            self.start_scan()
 
     def on_services(self, status, services):
+        Logger.info("Services discovered: %s" % services)
         self._characteristics = (services.search(_UART_SERVICE_TX_UUID), services.search(_UART_SERVICE_RX_UUID))

companion/mynitcompanion.kv

 #:kivy 1.0.9
 
-DeviceListWidget:
+<DeviceListWidget>:
     device_buttons: device_buttons
 
     BoxLayout: