Support ESP-NOW connection in pyflix

Set arbitrary pymavlink connection string using device parameter or FLIX_DEVICE env variable.
pyflix@0.16.

tools/pyflix/README.md

@@ -28,6 +28,8 @@ from pyflix import Flix
 flix = Flix()  # create a Flix object and wait for connection
 ```
 
+If using ESP-NOW connection, specify the proxy's device name in `FLIX_DEVICE` environment variable or pass it to the constructor: `Flix(device='/dev/cu.usbserial-0001')`.
+
 ### Telemetry
 
 Basic telemetry is available through object properties. The property names generally match the corresponding variables in the firmware code:

tools/pyflix/flix.py

@@ -44,22 +44,27 @@ class Flix:
     _print_buffer: str = ''
     _modes = ['RAW', 'ACRO', 'STAB', 'AUTO']
 
-    def __init__(self, system_id: int=1, wait_connection: bool=True):
+    def __init__(self, system_id: int=1, wait_connection: bool=True, device=os.getenv('FLIX_DEVICE')):
         if not (0 <= system_id < 256):
             raise ValueError('system_id must be in range [0, 255]')
         self._setup_mavlink()
         self.system_id = system_id
         self._init_state()
-        try:
-            # Direct connection
-            logger.debug('Listening on port 14550')
-            self.connection: mavutil.mavfile = mavutil.mavlink_connection('udpin:0.0.0.0:14550', source_system=255)  # type: ignore
-        except OSError as e:
-            if e.errno != errno.EADDRINUSE:
-                raise
-            # Port busy - using proxy
-            logger.debug('Listening on port 14555 (proxy)')
-            self.connection: mavutil.mavfile = mavutil.mavlink_connection('udpin:0.0.0.0:14555', source_system=254)  # type: ignore
+        if device is not None:
+            # User defined connection
+            logger.debug(f'Connecting to {device}')
+            self.connection: mavutil.mavfile = mavutil.mavlink_connection(device, source_system=255)  # type: ignore
+        else:
+            try:
+                # Direct connection
+                logger.debug('Listening on port 14550')
+                self.connection: mavutil.mavfile = mavutil.mavlink_connection('udpin:0.0.0.0:14550', source_system=255)  # type: ignore
+            except OSError as e:
+                if e.errno != errno.EADDRINUSE:
+                    raise
+                # Port busy - using proxy
+                logger.debug('Listening on port 14555 (proxy)')
+                self.connection: mavutil.mavfile = mavutil.mavlink_connection('udpin:0.0.0.0:14555', source_system=254)  # type: ignore
         self.connection.target_system = system_id
         self.mavlink: mavlink.MAVLink = self.connection.mav
         self._event_listeners: Dict[str, List[Callable[..., Any]]] = {}

tools/pyproject.toml

@@ -1,6 +1,6 @@
 [project]
 name = "pyflix"
-version = "0.15"
+version = "0.16"
 description = "Python API for Flix drone"
 authors = [{ name="Oleg Kalachev", email="okalachev@gmail.com" }]
 license = "MIT"