Fix broken class matching on receive

adafruit_ble_broadcastnet.py

@@ -46,8 +46,8 @@
 
 def broadcast(measurement, *, broadcast_time=0.1, extended=False):
     """Broadcasts the given measurement for the given broadcast time. If extended is False and the
-       measurement would be too long, it will be split into multiple measurements for transmission.
-       """
+    measurement would be too long, it will be split into multiple measurements for transmission.
+    """
     global _sequence_number  # pylint: disable=global-statement,invalid-name
     for submeasurement in measurement.split(252 if extended else 31):
         submeasurement.sequence_number = _sequence_number
@@ -61,14 +61,17 @@ def broadcast(measurement, *, broadcast_time=0.1, extended=False):
 if not hasattr(os, "environ") or (
     "GITHUB_ACTION" not in os.environ and "READTHEDOCS" not in os.environ
 ):
-    device_address = "{:02x}{:02x}{:02x}{:02x}{:02x}{:02x}".format(  # pylint: disable=invalid-name
-        *reversed(
-            list(
-                _ble._adapter.address.address_bytes  # pylint: disable=protected-access
+    if _ble._adapter.address:  # pylint: disable=protected-access
+        device_address = "{:02x}{:02x}{:02x}{:02x}{:02x}{:02x}".format(  # pylint: disable=invalid-name
+            *reversed(
+                list(
+                    _ble._adapter.address.address_bytes  # pylint: disable=protected-access
+                )
             )
         )
-    )
-    """Device address as a string."""
+    else:
+        device_address = "000000000000"  # pylint: disable=invalid-name
+        """Device address as a string."""
 
 _MANUFACTURING_DATA_ADT = const(0xFF)
 _ADAFRUIT_COMPANY_ID = const(0x0822)
@@ -79,7 +82,10 @@ class AdafruitSensorMeasurement(Advertisement):
 
     # This prefix matches all
     match_prefixes = (
-        struct.pack("<BBH", 3, _MANUFACTURING_DATA_ADT, _ADAFRUIT_COMPANY_ID),
+        # Matches the sequence number field header (length+ID)
+        struct.pack(
+            "<BHBH", _MANUFACTURING_DATA_ADT, _ADAFRUIT_COMPANY_ID, 0x03, 0x0003
+        ),
     )
 
     manufacturer_data = LazyObjectField(
@@ -175,9 +181,16 @@ def __str__(self):
                     parts.append("{}={}".format(attr, str(value)))
         return "<{} {} >".format(self.__class__.__name__, " ".join(parts))
 
+    def __bytes__(self):
+        """The raw packet bytes."""
+        # Must reorder the ManufacturerData contents so the sequence number field is always first.
+        # Necessary to ensure that match_prefixes works right to reconstruct on the receiver.
+        self.data_dict[255].data.move_to_end(3, last=False)
+        return super().__bytes__()
+
     def split(self, max_packet_size=31):
         """Split the measurement into multiple measurements with the given max_packet_size. Yields
-           each submeasurement."""
+        each submeasurement."""
         current_size = 8  # baseline for mfg data and sequence number
         if current_size + len(self.manufacturer_data) < max_packet_size:
             yield self

examples/ble_broadcastnet_scan_test.py

@@ -0,0 +1,13 @@
+"""This example merely scans for broadcastnet packets to check that something is sending them."""
+
+import adafruit_ble
+import adafruit_ble_broadcastnet
+
+ble = adafruit_ble.BLERadio()
+
+print("scanning")
+# By providing Advertisement as well we include everything, not just specific advertisements.
+for advert in ble.start_scan(
+    adafruit_ble_broadcastnet.AdafruitSensorMeasurement, interval=0.5
+):
+    print(advert)