92 lines
2.5 KiB
Python
92 lines
2.5 KiB
Python
# Exemple pour générer des trames d'advertising pour le BLE
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from micropython import const
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import struct
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import bluetooth
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# Les trames d'advertising sont sont des paquets répétés ayant la structure suivante :
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# 1 octet indiquant la taille des données (N + 1)
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# 1 octet indiquant le type de données (voir les constantes ci-dessous)
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# N octets de données du type indiqué
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_ADV_TYPE_FLAGS = const(0x01)
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_ADV_TYPE_NAME = const(0x09)
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_ADV_TYPE_UUID16_COMPLETE = const(0x3)
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_ADV_TYPE_UUID32_COMPLETE = const(0x5)
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_ADV_TYPE_UUID128_COMPLETE = const(0x7)
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_ADV_TYPE_UUID16_MORE = const(0x2)
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_ADV_TYPE_UUID32_MORE = const(0x4)
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_ADV_TYPE_UUID128_MORE = const(0x6)
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_ADV_TYPE_APPEARANCE = const(0x19)
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_ADV_TYPE_MANUFACTURER = const(0xFF)
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# Génère une trame qui sera passée à la méthode gap_advertise(adv_data=...).
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def adv_payload(
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limited_disc=False,
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br_edr=False,
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name=None,
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services=None,
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appearance=0,
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manufacturer=0,
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):
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payload = bytearray()
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def _append(adv_type, value):
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nonlocal payload
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payload += struct.pack("BB", len(value) + 1, adv_type) + value
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_append(
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_ADV_TYPE_FLAGS,
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struct.pack("B", (0x01 if limited_disc else 0x02) + (0x00 if br_edr else 0x04)),
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)
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if name:
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_append(_ADV_TYPE_NAME, name)
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if services:
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for uuid in services:
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b = bytes(uuid)
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if len(b) == 2:
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_append(_ADV_TYPE_UUID16_COMPLETE, b)
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elif len(b) == 4:
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_append(_ADV_TYPE_UUID32_COMPLETE, b)
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elif len(b) == 16:
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_append(_ADV_TYPE_UUID128_COMPLETE, b)
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if appearance:
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# Voir org.bluetooth.characteristic.gap.appearance.xml
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_append(_ADV_TYPE_APPEARANCE, struct.pack("<h", appearance))
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if manufacturer:
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_append(_ADV_TYPE_MANUFACTURER, manufacturer)
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return payload
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def decode_field(payload, adv_type):
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i = 0
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result = []
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while i + 1 < len(payload):
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if payload[i + 1] == adv_type:
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result.append(payload[i + 2 : i + payload[i] + 1])
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i += 1 + payload[i]
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return result
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def decode_name(payload):
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n = decode_field(payload, _ADV_TYPE_NAME)
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return str(n[0], "utf-8") if n else ""
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def decode_services(payload):
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services = []
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for u in decode_field(payload, _ADV_TYPE_UUID16_COMPLETE):
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services.append(bluetooth.UUID(struct.unpack("<h", u)[0]))
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for u in decode_field(payload, _ADV_TYPE_UUID32_COMPLETE):
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services.append(bluetooth.UUID(struct.unpack("<d", u)[0]))
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for u in decode_field(payload, _ADV_TYPE_UUID128_COMPLETE):
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services.append(bluetooth.UUID(u))
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return services
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