[PYTHON] Take the value of SwitchBot thermo-hygrometer with Raspberry Pi

Purpose

As the title says. I fully refer to the following articles. Thank you very much. The code is almost the same, so if you point out, we will delete it immediately.

Log the value of SwitchBot thermo-hygrometer with Raspberry Pi https://qiita.com/c60evaporator/items/7c3156a6bbb7c6c59052

There was a part that didn't work in my environment, so I'll put the code that worked as a private log.

environment

• Raspberry Pi 4 Model B Rev 1.2
• SwitchBot Thermo-Hygrometer (https://www.switchbot.jp/meter)

Check the Mac Address of the SwitchBot thermo-hygrometer

You can check it from the smartphone application.

Check if the sensor is skipping data

pi@raspberrypi:~ $ sudo hcitool lescan | grep EB:F6:31:8C:1F:E9
EB:F6:31:8C:1F:E9 (unknown)
EB:F6:31:8C:1F:E9 (unknown)
EB:F6:31:8C:1F:E9 (unknown)

What is this command?

NAME
       hcitool - configure Bluetooth connections

DESCRIPTION
       hcitool  is  used to configure Bluetooth connections and send some spe-
       cial command to Bluetooth devices. If no command is given,  or  if  the
       option -h is used, hcitool prints some usage information and exits.

Get value in Python

Use bluepy. Refer to the linked URL.

pi@raspberrypi:~ $ sudo install libglib2.0-dev
pi@raspberrypi:~ $ pip3 install bluepy
pi@raspberrypi:~ $ cd .local/lib/python3.7/site-packages/bluepy
pi@raspberrypi:~ $ sudo setcap 'cap_net_raw,cap_net_admin+eip' bluepy-helper

Python script

switchbot.py

from bluepy import btle
import struct

class SwitchbotScanDelegate(btle.DefaultDelegate):
    def __init__(self, macaddr):
        btle.DefaultDelegate.__init__(self)
        self.sensorValue = None
        self.macaddr = macaddr

    def handleDiscovery(self, dev, isNewDev, isNewData):
        if dev.addr == self.macaddr:
            for (adtype, desc, value) in dev.getScanData():  
                if desc == '16b Service Data':
                    self._decodeSensorData(value)

    def _decodeSensorData(self, valueStr):
        valueBinary = bytes.fromhex(valueStr[4:])
        batt = valueBinary[2] & 0b01111111
        isTemperatureAboveFreezing = valueBinary[4] & 0b10000000
        temp = ( valueBinary[3] & 0b00001111 ) / 10 + ( valueBinary[4] & 0b01111111 )
        if not isTemperatureAboveFreezing:
            temp = -temp
        humid = valueBinary[5] & 0b01111111
        self.sensorValue = {
            'SensorType': 'SwitchBot',
            'Temperature': temp,
            'Humidity': humid,
            'BatteryVoltage': batt
        }

main.py

from bluepy import btle
from switchbot import SwitchbotScanDelegate

scanner = btle.Scanner().withDelegate(SwitchbotScanDelegate('eb:f6:31:8c:1f:e9'))
scanner.scan(5.0)
print(scanner.delegate.sensorValue)

pi@raspberrypi:~ $ python3 ./main.py
{'SensorType': 'SwitchBot', 'Temperature': 25.2, 'Humidity': 68, 'BatteryVoltage': 100}