2a7546fe8b
Implement Gateway class that discovers Nordic Thingy:52 nodes via BLE
and publishes sensor data to MQTT broker on each notification received.
- Automatic node discovery via BLE service UUID (ef680100)
- GATT notifications for temperature, humidity and CO2
- Publish immediately on reception to {gateway_id}/{mac}/update
- Connection timeout to avoid blocking on unreachable nodes
- Disconnection detection and automatic reintegration into scan
- Logging with DEBUG/INFO/WARNING/ERROR levels
Assisted-by: Claude:claude-sonnet-4-6 — debugging BLE parallel connections (BlueZ InProgress error), GATT UUID discovery (ef680100 vs ef680200), byte decoding for temperature/humidity/CO2, async connection timeout implementation
161 lines
6.3 KiB
Python
161 lines
6.3 KiB
Python
import asyncio
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import json
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import logging
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import os
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from datetime import datetime, timezone
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from bleak import BleakClient, BleakScanner
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import paho.mqtt.client as mqtt
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# Logging — use DEBUG for development, INFO for normal operation
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logging.basicConfig(
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level=logging.INFO,
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format="%(asctime)s [%(levelname)s] %(message)s",
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datefmt="%Y-%m-%dT%H:%M:%S"
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)
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log = logging.getLogger(__name__)
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class Gateway:
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"""BLE to MQTT gateway for Nordic Thingy:52 sensor nodes."""
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def __init__(self, config: dict):
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self.gateway_id = config["gateway_id"]
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self.mqtt_broker = config["mqtt"]["broker"]
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self.mqtt_port = config["mqtt"]["port"]
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# GATT UUIDs loaded from config
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# ef680100 is advertised in BLE packets — used for discovery
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# environment service (ef680200) is only accessible after connection
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self.service_uuid = config["ble"]["service_uuid"]
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self.uuid_temp = config["ble"]["characteristics"]["temperature"]
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self.uuid_co2 = config["ble"]["characteristics"]["co2"]
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self.uuid_humidity= config["ble"]["characteristics"]["humidity"]
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# Runtime state
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# latest : last known sensor values per MAC address
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# connecting: MACs currently being connected (avoids duplicate attempts)
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self.latest = {}
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self.connecting = set()
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self.scanner = None
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# MQTT client setup
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self.mqttc = mqtt.Client(mqtt.CallbackAPIVersion.VERSION2)
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self.mqttc.connect(self.mqtt_broker, self.mqtt_port)
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self.mqttc.loop_start()
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log.info(f"Gateway ID : {self.gateway_id}")
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log.info(f"MQTT broker: {self.mqtt_broker}:{self.mqtt_port}")
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log.info("MQTT client connected")
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# Publish immediately on reception — topic: {gateway_id}/{mac}/update
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# Only include fields that have been received at least once
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def publish(self, mac: str, data: dict):
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topic = f"{self.gateway_id}/{mac}/update"
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payload = {"timestamp": datetime.now(timezone.utc).strftime("%Y-%m-%dT%H:%M:%SZ")}
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if data.get("temp") is not None:
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payload["temp"] = data.get("temp")
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if data.get("humidity") is not None:
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payload["humidity"] = data.get("humidity")
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if data.get("co2") is not None:
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payload["co2_ppm"] = data.get("co2")
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self.mqttc.publish(topic, json.dumps(payload))
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log.info(f"Published to {topic} : {payload}")
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# BLE handlers — called by bleak on each notification
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# Temp : 2 bytes (integer part + decimal part)
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# CO2 : uint16 little-endian, 0 means sensor is warming up
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# Humidity: 1 byte, direct percentage value
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def handle_temp(self, mac: str, sender, data: bytearray):
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temp = data[0] + data[1] / 100
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if mac in self.latest:
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self.latest[mac]["temp"] = round(temp, 2)
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self.publish(mac, self.latest[mac])
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def handle_humidity(self, mac: str, sender, data: bytearray):
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if mac in self.latest:
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self.latest[mac]["humidity"] = data[0]
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self.publish(mac, self.latest[mac])
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def handle_co2(self, mac: str, sender, data: bytearray):
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co2 = int.from_bytes(data[0:2], byteorder='little')
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if co2 == 0:
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log.warning(f"{mac} | CO2 sensor still warming up")
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return
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if mac in self.latest:
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self.latest[mac]["co2"] = co2
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self.publish(mac, self.latest[mac])
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# Stop scanner before connecting — BlueZ does not support both simultaneously.
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# Scanner is restarted once the device is connected and notifications registered.
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async def connect_device(self, mac: str):
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log.info(f"Attempting to connect to {mac}...")
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try:
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if self.scanner:
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await self.scanner.stop()
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await asyncio.sleep(1)
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log.info(f"Connecting to {mac}...")
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def on_disconnect(client):
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log.warning(f"{mac} disconnected, removing from active nodes")
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self.latest.pop(mac, None)
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client = BleakClient(mac, disconnected_callback=on_disconnect)
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try:
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await asyncio.wait_for(client.connect(), timeout=10.0)
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except asyncio.TimeoutError:
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log.error(f"Connection timeout for {mac}")
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self.connecting.discard(mac)
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self.latest.pop(mac, None)
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if self.scanner:
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await self.scanner.start()
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return
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self.connecting.discard(mac)
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self.latest[mac] = {"temp": None, "humidity": None, "co2": None}
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log.info(f"{mac} connected")
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await client.start_notify(self.uuid_temp,
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lambda s, d: self.handle_temp(mac, s, d))
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await client.start_notify(self.uuid_co2,
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lambda s, d: self.handle_co2(mac, s, d))
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await client.start_notify(self.uuid_humidity,
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lambda s, d: self.handle_humidity(mac, s, d))
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await asyncio.sleep(1)
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await self.scanner.start()
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log.info("Scanner restarted, waiting for additional nodes")
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except Exception as e:
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log.error(f"Connection error for {mac}: {e}")
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self.connecting.discard(mac)
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self.latest.pop(mac, None)
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if self.scanner:
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await self.scanner.start()
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# BLE discovery callback — filters on Thingy:52 service UUID
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def on_device_found(self, device, adv_data):
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uuids = [str(u).lower() for u in adv_data.service_uuids]
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if self.service_uuid.lower() in uuids \
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and device.address not in self.latest \
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and device.address not in self.connecting:
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self.connecting.add(device.address)
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log.info(f"New node detected: {device.address}")
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asyncio.ensure_future(self.connect_device(device.address))
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# Start BLE scan and run indefinitely
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async def run(self):
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log.info("BLE scan started, waiting for Thingy:52 nodes...")
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self.scanner = BleakScanner(detection_callback=self.on_device_found)
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await self.scanner.start()
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while True:
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await asyncio.sleep(1)
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if __name__ == "__main__":
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config_path = os.path.join(os.path.dirname(__file__), "config.json")
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with open(config_path, "r") as f:
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config = json.load(f)
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gateway = Gateway(config)
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asyncio.run(gateway.run())
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