Implement basic functionality

Author: tekktrik

adafruit_ble_beacon.py

@@ -32,8 +32,130 @@
 # * Adafruit's Register library: https://github.com/adafruit/Adafruit_CircuitPython_Register
 """
 
+import struct
+from micropython import const
 import _bleio
-from adafruit_ble.
+from adafruit_ble.advertising import Advertisement, Struct, AdvertisingDataField
+from adafruit_ble.advertising.standard import ManufacturerData
+
+try:
+    from typing import Optional, Union, Any, Type, Tuple, Sequence
+except ImportError:
+    pass
 
 __version__ = "0.0.0+auto.0"
 __repo__ = "https://github.com/tekktrik/Adafruit_CircuitPython_BLE_Beacon.git"
+
+_MANUFACTURING_DATA_ADT = const(0xFF)
+
+_APPLE_COMPANY_ID = const(0x004C)
+_IBEACON_TYPE = const(0x02)
+_IBEACON_LENGTH = const(0x15)
+
+# TODO: fix this
+_APPLE_COMPANY_ID_FLIPPED = const(0x4C00)
+
+
+class MultiStruct(AdvertisingDataField):
+    """`struct` encoded data in an Advertisement."""
+
+    def __init__(self, struct_format: str, *, advertising_data_type: int) -> None:
+        self._format = struct_format
+        self._adt = advertising_data_type
+
+    def __get__(
+        self, obj: Optional["Advertisement"], cls: Type["Advertisement"]
+    ) -> Optional[Union[Tuple, "Struct"]]:
+        if obj is None:
+            return self
+        if self._adt not in obj.data_dict:
+            return None
+        return struct.unpack(self._format, obj.data_dict[self._adt])
+
+    def __set__(self, obj: "Advertisement", value: Sequence) -> None:
+        obj.data_dict[self._adt] = struct.pack(self._format, *value)
+
+class _BeaconAdvertisement(Advertisement):
+    """Advertisement for location beacons like iBeacon"""
+
+    path_loss_const: int = 3
+    """The path loss constant, typically between 2-4"""
+
+    @property
+    def distance(self) -> float:
+        """The approximate distance to the beacon"""
+
+        return 10**((self.beacon_tx_power - self.rssi) / (10*self.path_loss_const))
+
+    @property
+    def beacon_tx_power(self) -> int:
+        raise NotImplementedError("Must be defined in beacon subclass")
+
+    
+
+class iBeaconAdvertisement(_BeaconAdvertisement):
+
+    match_prefixes = (struct.pack("<BHBB", _MANUFACTURING_DATA_ADT, _APPLE_COMPANY_ID, _IBEACON_TYPE, _IBEACON_LENGTH),)
+
+    _data_format = ">HBBQQHHb"
+    _beacon_data = MultiStruct(_data_format, advertising_data_type=0xFF)
+
+    def __init__(self, *, entry: Optional[_bleio.ScanEntry] = None, ) -> None:
+        super().__init__(entry=entry)
+
+        if not entry:
+            self._init_struct()
+    
+    @property
+    def uuid(self) -> bytes:
+        _, _, _, uuid_msb, uuid_lsb, _, _, _ = self._beacon_data
+        return struct.pack(">QQ", uuid_msb, uuid_lsb)
+
+    @uuid.setter
+    def uuid(self, id: bytes) -> None:
+        uuid_msb, uuid_lsb = struct.unpack(">QQ", id)
+        self._set_struct_index(3, uuid_msb)
+        self._set_struct_index(4, uuid_lsb)
+
+
+    @property
+    def major(self) -> int:
+        _, _, _, _, _, major, _, _ = self._beacon_data
+        return major
+
+    @major.setter
+    def major(self, number: int) -> None:
+        #flipped = self.flip_endian(number)
+        self._set_struct_index(5, number)
+
+    @property
+    def minor(self) -> int:
+        _, _, _, _, _, _, minor, _ = self._beacon_data
+        return minor
+
+    @minor.setter
+    def minor(self, number: int) -> None:
+        self._set_struct_index(6, number)
+
+    @property
+    def beacon_tx_power(self) -> int:
+        _, _, _, _, _, _, _, tx_power = self._beacon_data
+        return tx_power
+
+    @beacon_tx_power.setter
+    def beacon_tx_power(self, power: int) -> None:
+        self._set_struct_index(7, power)
+
+    def _set_struct_index(self, index: int, value: int) -> int:
+        current_beacon_data = list(self._beacon_data)
+        flipped = self.flip_endian(value, index)
+        current_beacon_data[index] = flipped
+        self._beacon_data = current_beacon_data
+
+    def _init_struct(self) -> None:
+        self._beacon_data = (_APPLE_COMPANY_ID_FLIPPED, _IBEACON_TYPE, _IBEACON_LENGTH, 0, 0, 0, 0, 0)
+
+    def flip_endian(self, number: int, index: int):
+        index_format = self._data_format[index+1]
+        temp_bytes = struct.pack("<" + index_format, number)
+        return struct.unpack("<" + index_format, temp_bytes)[0]

examples/ble_beacon_sendtest.py

@@ -0,0 +1,17 @@
+import time
+from adafruit_ble import BLERadio
+from adafruit_ble_beacon import iBeaconAdvertisement
+
+ble = BLERadio()
+
+advertisement = iBeaconAdvertisement()
+advertisement.uuid = b"circuitPython123"
+advertisement.major = 1
+advertisement.minor = 32
+advertisement.beacon_tx_power = -80
+
+while True:
+    ble.start_advertising(advertisement)
+    time.sleep(10)
+    ble.stop_advertising()
+    time.sleep(3)

examples/ble_beacon_simpletest.py

@@ -2,3 +2,20 @@
 # SPDX-FileCopyrightText: Copyright (c) 2022 Alec Delaney for Adafruit Industries
 #
 # SPDX-License-Identifier: Unlicense
+
+import time
+from adafruit_ble import BLERadio
+from adafruit_ble_beacon import iBeaconAdvertisement
+
+ble = BLERadio()
+
+while True:
+    for entry in ble.start_scan(iBeaconAdvertisement, minimum_rssi=-120, timeout=3):
+        entry: iBeaconAdvertisement
+        print("Beacon Power", entry.beacon_tx_power)
+        print("UUID:", entry.uuid)
+        print("Major", entry.major)
+        print("Minor:", entry.minor)
+        print("Distance:", entry.distance)
+        time.sleep(1)
+    time.sleep(3)