Implement discovery of RX/TX characteristics

companion/bluetooth.py

@@ -5,6 +5,8 @@ from able.filters import ServiceUUIDFilter
 from kivy.logger import Logger
 
 _UART_SERVICE_UUID = "6e400001-b5a3-f393-e0a9-e50e24dcca9e"
+_UART_SERVICE_TX_UUID = "6e400002"
+_UART_SERVICE_RX_UUID = "6e400003"
 
 
 class MynitBluetooth(BluetoothDispatcher):
@@ -15,6 +17,7 @@ class MynitBluetooth(BluetoothDispatcher):
         self._app = app
         self._available_devices = set()
         self._current_device = None
+        self._characteristics = None, None
 
         Logger.info("Starting BLE scanning")
         self.start_scan(filters=[ServiceUUIDFilter(_UART_SERVICE_UUID)])
@@ -39,6 +42,7 @@ class MynitBluetooth(BluetoothDispatcher):
             Logger.warning("Connection failed, disconnecting and resetting")
             self.close_gatt()
             self._current_device = None
+            self._characteristics = None, None
 
     def on_services(self, status, services):
-        pass
+        self._characteristics = (services.search(_UART_SERVICE_TX_UUID), services.search(_UART_SERVICE_RX_UUID)