Edlora Python

Packet Class

The core data structure encapsulating a message. It handles the framing, validation, and payload.

Constants:

• Packet.SYNC_BYTE = 0xED
• Packet.BROADCAST_ID = 0xFF
• Packet.MAX_PAYLOAD_SIZE = 240

Initialization:

from edlora import Packet, MsgType

packet = Packet(
    sender_id=0,               # ID of sender (0-255)
    receiver_id=0,             # Target ID or 0xFF for broadcast (0-255)
    version=0x02,              # Protocol Version (Fixed per spec)
    flags=0,                   # Bitwise attributes (e.g. ACK_REQUIRED)
    msg_type=MsgType.CUSTOM,   # The message type (MsgType enum)
    seq_num=0,                 # Packet sequence number (0-255)
    timestamp=0,               # Timestamp in milliseconds (32-bit uint)
    payload=b""                # Raw payload bytes
)

Packing & Unpacking (Binary Serialization):

• packet.pack() -> bytes Returns the full packet bytes ready for transmission, including sync byte, header, payload, and the Little Endian CRC16 checksum. Validates fields before packing.
• Packet.unpack(buffer: bytes) -> Packet Class method that parses received bytes back into a Packet object. Automatically validates the SYNC_BYTE, payload length, and the CRC16 checksum. Raises ValueError on bad packets.

Helpful Methods:

• packet.is_targeted_to(my_id: int) -> bool Checks if the packet receiver_id matches my_id or 0xFF (broadcast).
• packet.create_ack(my_id: int, current_timestamp: int) -> Packet Generates an acknowledgment packet targeted back to the sender containing the original seq_num as a 1-byte payload.
• packet.set_payload_string(text: str) Encodes a UTF-8 string directly into the payload bytes, truncating to MAX_PAYLOAD_SIZE.
• packet.get_payload_string() -> str Decodes the payload bytes back to a UTF-8 string (uses errors='replace').

XorCipher Class

A lightweight cryptographic cipher for obfuscating payloads.

from edlora.crypto import XorCipher 
# Note: depending on imports, it might also be accessed as `from edlora_crypto import XorCipher` as shown in README docs.

cipher = XorCipher(key=0xAA)
encrypted_packet = cipher.process(packet) # Processes payload IN-PLACE

process() mutates packet.payload and returns the same packet object.

Common Workflows

1. Transmitting a Packet

import time
from edlora import Packet, MsgType

# 1. Create a packet
tx_packet = Packet(
    sender_id=0xFF,   # Ground Station ID
    receiver_id=0x10, # Target Rocket ID
    msg_type=MsgType.COMMAND,
    seq_num=42,
    timestamp=int(time.time() * 1000) % 0xFFFFFFFF
)

# 2. Set the payload
tx_packet.set_payload_string("DEPLOY PARACHUTE")

# 3. Get bytes for transmission
bytes_to_send = tx_packet.pack()

# Write `bytes_to_send` to your serial/USB LoRa module
# serial_port.write(bytes_to_send)

2. Receiving and Processing Packets

from edlora import Packet, MsgType
import struct

# Receive raw bytes from your LoRa module
# rx_bytes = serial_port.read(...)