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#!/usr/bin/env python3
"""
Weather Board → Home Assistant via MQTT with auto-discovery.
Reads BME280 (temperature, humidity, pressure) and SI1132 (UV index,
visible light, IR) over I2C and publishes to an MQTT broker using
Home Assistant's MQTT discovery protocol.
Usage:
python3 mqtt_ha.py
"""
import json
import signal
import sys
import time
import paho.mqtt.client as mqtt
import BME280
import SI1132
# ── MQTT settings ────────────────────────────────────────────────────────────
MQTT_HOST = "192.168.1.135"
MQTT_PORT = 1883
MQTT_USER = "co2meter"
MQTT_PASS = "co2meter"
# ── I2C bus ──────────────────────────────────────────────────────────────────
I2C = "/dev/i2c-1"
# ── Home Assistant discovery identifiers ─────────────────────────────────────
DEVICE_ID = "weather_board_office"
DEVICE_NAME = "Weather Board"
ROOM = "Office"
HA_DISCOVERY_PREFIX = "homeassistant"
STATE_TOPIC = f"{HA_DISCOVERY_PREFIX}/sensor/{DEVICE_ID}/state"
# How often to read & publish (seconds)
PUBLISH_INTERVAL = 10
# ── Sensor definitions for HA auto-discovery ─────────────────────────────────
# Each entry maps to one Home Assistant sensor entity.
SENSORS = [
{
"key": "temperature",
"name": "Temperature",
"device_class": "temperature",
"unit": "°C",
"icon": None,
"state_class": "measurement",
},
{
"key": "humidity",
"name": "Humidity",
"device_class": "humidity",
"unit": "%",
"icon": None,
"state_class": "measurement",
},
{
"key": "pressure",
"name": "Pressure",
"device_class": "atmospheric_pressure",
"unit": "hPa",
"icon": None,
"state_class": "measurement",
},
{
"key": "uv_index",
"name": "UV Index",
"device_class": None,
"unit": "UV index",
"icon": "mdi:sun-wireless",
"state_class": "measurement",
},
{
"key": "visible_light",
"name": "Visible Light",
"device_class": "illuminance",
"unit": "lx",
"icon": None,
"state_class": "measurement",
},
{
"key": "ir",
"name": "Infrared",
"device_class": None,
"unit": "lx",
"icon": "mdi:sun-wireless-outline",
"state_class": "measurement",
},
]
# ── Shared HA device block (appears once per entity, links them together) ────
HA_DEVICE = {
"identifiers": [DEVICE_ID],
"name": DEVICE_NAME,
"manufacturer": "ODROID",
"model": "Weather Board",
"suggested_area": ROOM,
}
def publish_discovery(client: mqtt.Client) -> None:
"""Publish MQTT discovery config messages for every sensor entity."""
for sensor in SENSORS:
uid = f"{DEVICE_ID}_{sensor['key']}"
config_topic = (
f"{HA_DISCOVERY_PREFIX}/sensor/{DEVICE_ID}/{sensor['key']}/config"
)
payload = {
"name": sensor["name"],
"unique_id": uid,
"object_id": uid,
"state_topic": STATE_TOPIC,
"value_template": "{{ value_json." + sensor["key"] + " }}",
"unit_of_measurement": sensor["unit"],
"state_class": sensor["state_class"],
"device": HA_DEVICE,
}
if sensor["device_class"]:
payload["device_class"] = sensor["device_class"]
if sensor["icon"]:
payload["icon"] = sensor["icon"]
client.publish(config_topic, json.dumps(payload), retain=True)
print(f" discovery: {config_topic}")
def read_sensors(bme: BME280.BME280, si: SI1132.SI1132) -> dict:
"""Read all sensors and return a dict ready for JSON serialisation."""
# Temperature must be read first — it sets t_fine used by humidity/pressure
temperature = bme.read_temperature()
humidity = bme.read_humidity()
pressure = bme.read_pressure() / 100.0 # Pa → hPa
uv_index = si.readUV() / 100.0
visible_light = si.readVisible()
ir = si.readIR()
return {
"temperature": round(temperature, 2),
"humidity": round(humidity, 2),
"pressure": round(pressure, 2),
"uv_index": round(uv_index, 2),
"visible_light": round(visible_light, 1),
"ir": round(ir, 1),
}
def main() -> None:
# ── Initialise I2C sensors ───────────────────────────────────────────
print("Initialising sensors...")
si = SI1132.SI1132(I2C)
# Normal mode, 2× oversampling for humidity, pressure, temperature
bme = BME280.BME280(I2C, 0x03, 0x02, 0x02, 0x02)
print(" BME280 + SI1132 ready")
# ── Connect to MQTT broker ───────────────────────────────────────────
client = mqtt.Client(client_id=DEVICE_ID)
client.username_pw_set(MQTT_USER, MQTT_PASS)
def on_connect(cl, _userdata, _flags, rc):
if rc == 0:
print(f" connected to MQTT broker at {MQTT_HOST}:{MQTT_PORT}")
publish_discovery(cl)
else:
print(f" MQTT connection failed (rc={rc})")
client.on_connect = on_connect
client.will_set(STATE_TOPIC, payload="", retain=False)
print("Connecting to MQTT...")
client.connect(MQTT_HOST, MQTT_PORT, keepalive=60)
client.loop_start()
# ── Graceful shutdown ────────────────────────────────────────────────
running = True
def _stop(signum, _frame):
nonlocal running
print(f"\nCaught signal {signum}, shutting down...")
running = False
signal.signal(signal.SIGINT, _stop)
signal.signal(signal.SIGTERM, _stop)
# ── Main loop ────────────────────────────────────────────────────────
print("Publishing sensor data...\n")
while running:
try:
data = read_sensors(bme, si)
payload = json.dumps(data)
client.publish(STATE_TOPIC, payload, retain=False)
print(f" {payload}")
except Exception as e:
print(f" sensor read error: {e}")
# Sleep in small increments so we can react to signals promptly
for _ in range(PUBLISH_INTERVAL * 10):
if not running:
break
time.sleep(0.1)
# ── Cleanup ──────────────────────────────────────────────────────────
client.loop_stop()
client.disconnect()
print("Done.")
if __name__ == "__main__":
main()
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