139 lines
4.4 KiB
Python
139 lines
4.4 KiB
Python
import time
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import uuid
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from sx1262 import SX1262
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import uasyncio as asyncio
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from queue import Queue
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class FixedDeque:
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def __init__(self, maxlen):
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self.maxlen = maxlen
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self.data = []
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def append(self, x):
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if len(self.data) >= self.maxlen:
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self.data.pop(0)
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self.data.append(x)
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def __iter__(self):
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return iter(self.data)
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class LoRaMessage:
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def __init__(self, sender_id: str, recipient_id: str, payload: bytes):
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self.sender_id = sender_id
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self.recipient_id = recipient_id
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self.payload = payload
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self.message_id = str(uuid.uuid4())
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self.lifetime = 7
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def encode(self) -> bytes:
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encoded = bytearray()
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encoded.append(len(self.sender_id))
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encoded.extend(self.sender_id.encode("utf-8"))
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encoded.append(len(self.recipient_id))
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encoded.extend(self.recipient_id.encode("utf-8"))
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encoded.extend(self.payload)
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return bytes(encoded)
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@staticmethod
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def decode(data: bytes):
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sender_id_len = data[0]
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sender_id = data[1:1+sender_id_len].decode("utf-8")
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recipient_id_len = data[1+sender_id_len]
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recipient_id = data[2+sender_id_len:2+sender_id_len+recipient_id_len].decode("utf-8")
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payload = data[2+sender_id_len+recipient_id_len:]
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return LoRaMessage(sender_id=sender_id, recipient_id=recipient_id, payload=payload)
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class LoRaHandler:
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def __init__(self):
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print("Initializing LoRa...")
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self.my_id = str(uuid.uuid4())
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# initialize our radio, im using the HAT SX1262 hat for the pico
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self.radio = SX1262(spi_bus=1, clk=10, mosi=11, miso=12, cs=3, irq=20, rst=15, gpio=2)
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self.radio.begin(freq=915, bw=125, power=22)
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self.radio.setBlockingCallback(False, self.irq)
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self.recent_messages = FixedDeque(32)
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self.neighbours = set()
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self.message_queue = Queue()
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def send(self, data: bytes, recipient_id: str):
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msg_bytes = LoRaMessage(sender_id=self.my_id, recipient_id=recipient_id, payload=data).encode()
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self.radio.send(msg_bytes)
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def has_seen_message(self, msg: LoRaMessage) -> bool:
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if msg.message_id in self.recent_messages:
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return True
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self.recent_messages.append(msg.message_id)
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return False
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def forward(self, msg: LoRaMessage):
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# ensure we don't process a message twice
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if self.has_seen_message(msg):
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return
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msg_bytes = msg.encode()
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self.radio.send(msg_bytes)
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def advertise(self):
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# send an advertisement message to let neighbors know we're here
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self.send(b"ADVERTISE", recipient_id="BROADCAST")
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def on_receive(self, msg: LoRaMessage):
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# ensure we don't process a message twice
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if self.has_seen_message(msg):
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return
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# messages has a lifetime to prevent infinite loops.
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# if we receive a message with lifetime <= 0 we just drop it,
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# otherwise we decrement the lifetime and forward it to all
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# neighbors except the sender
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msg.lifetime -= 1
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if msg.lifetime <= 0:
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return
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# forward messages if they aren't meant for us
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if (msg.recipient_id != self.my_id) and msg.recipient_id != "BROADCAST":
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print("Forwarding message...")
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self.forward(msg)
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return
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if msg.payload == b"ADVERTISE":
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if not msg.sender_id in self.neighbours:
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print(f"Neighbour discovered: {msg.sender_id}")
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self.neighbours.add(msg.sender_id)
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# tell the sender we heard them by sending a ping back
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self.send(b"Ping!", msg.sender_id)
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self.forward(msg)
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return
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asyncio.create_task(self.message_queue.put(msg))
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def irq(self, events):
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#print(f"LORA EVENT: {events}")
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if events & SX1262.RX_DONE:
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msg, err = self.radio.recv()
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error = SX1262.STATUS[err]
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if error != "ERR_NONE":
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print(f"Error receiving message: {error}")
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return
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self.on_receive(LoRaMessage.decode(msg))
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elif events & SX1262.TX_DONE:
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pass
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#print('TX done.') |