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# SPDX-FileCopyrightText: 2021 Dan Halbert, written for Adafruit Industries
# SPDX-FileCopyrightText: Copyright (c) 2021 Adafruit Industries for Adafruit Industries LLC
# SPDX-License-Identifier: MIT
BLE Support for Xiaomi LYWSD03MMC Thermometer/Hygrometer
* Author(s): Adafruit Industries
Implementation Notes
**Software and Dependencies:**
* Adafruit CircuitPython firmware for the supported boards:
import struct
import _bleio
from import Service
from adafruit_ble.uuid import VendorUUID
from adafruit_ble.characteristics import Characteristic, ComplexCharacteristic
__version__ = "0.0.0-auto.0"
__repo__ = ""
class _Readings(ComplexCharacteristic):
"""Notify-only characteristic of temperature/humidity"""
uuid = VendorUUID("ebe0ccc1-7a0a-4b0c-8a1a-6ff2997da3a6")
def __init__(self):
def bind(self, service):
"""Bind to an LYWSD03MMCService."""
bound_characteristic = super().bind(service)
# Use a PacketBuffer that can store one packet to receive the data.
return _bleio.PacketBuffer(bound_characteristic, buffer_size=1)
class LYWSD03MMCService(Service):
"""Service for reading from an LYWSD03MMC sensor."""
def __init__(self, service=None):
# Defer creating buffers until needed, since MTU is not known yet.
self._settings_result_buf = None
self._readings_buf = None
uuid = VendorUUID("ebe0ccb0-7a0a-4b0c-8a1a-6ff2997da3a6")
readings = _Readings()
def temperature_humidity(self):
"""Return a tuple of (temperature, humidity)."""
if self._readings_buf is None:
self._readings_buf = bytearray(self.readings.incoming_packet_length)
data = self._readings_buf
length = self.readings.readinto(data)
if length > 0:
low_temp, high_temp, hum = struct.unpack_from("<BBB", data)
sign = high_temp & 0x80
temp = ((high_temp & 0x7F) << 8) | low_temp
if sign:
temp = temp - 32767
temp = temp / 100
return (temp, hum)
# No data.
return None