69 lines
1.7 KiB
Python
69 lines
1.7 KiB
Python
# Copyright (C) 2026 Hector van der Aa <hector@h3cx.dev>
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# Copyright (C) 2026 Association Exergie <association.exergie@gmail.com>
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# SPDX-License-Identifier: MIT
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import struct
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from dataclasses import dataclass
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UART_MAGIC = b"\xAA\x55\xAA\x55"
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LORA_HEADER_FORMAT = "<BBBBH"
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UART_HEADER_FORMAT = "<4sB"
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PACKET1_FORMAT = "<4s"
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PACKET2_FORMAT = "<Ifffff"
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LORA_HEADER_SIZE = struct.calcsize(LORA_HEADER_FORMAT)
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UART_HEADER_SIZE = struct.calcsize(UART_HEADER_FORMAT)
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PACKET1_SIZE = struct.calcsize(PACKET1_FORMAT)
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PACKET2_SIZE = struct.calcsize(PACKET2_FORMAT)
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@dataclass
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class TelemetryLoRaHeader:
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source: int
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dest: int
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version: int
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size: int
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crc16: int
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@dataclass
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class TelemetryPacket1:
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ping: bytes
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@dataclass
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class TelemetryPacket2:
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time_stamp: int
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vbat: float
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teng: float
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lat: float
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lng: float
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speed: float
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def crc16_ccitt(data: bytes) -> int:
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crc = 0xFFFF
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for byte in data:
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crc ^= byte << 8
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for _ in range(8):
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if crc & 0x8000:
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crc = ((crc << 1) ^ 0x1021) & 0xFFFF
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else:
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crc = (crc << 1) & 0xFFFF
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return crc
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def unpack_lora_header(data: bytes) -> TelemetryLoRaHeader:
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source, dest, version, size, crc16 = struct.unpack(LORA_HEADER_FORMAT, data[:LORA_HEADER_SIZE])
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return TelemetryLoRaHeader(source, dest, version, size, crc16)
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def unpack_packet1(payload: bytes) -> TelemetryPacket1:
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(ping,) = struct.unpack(PACKET1_FORMAT, payload[:PACKET1_SIZE])
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return TelemetryPacket1(ping)
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def unpack_packet2(payload: bytes) -> TelemetryPacket2:
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time_stamp, vbat, teng, lat, lng, speed = struct.unpack(PACKET2_FORMAT, payload[:PACKET2_SIZE])
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return TelemetryPacket2(time_stamp, vbat, teng, lat, lng, speed)
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