Log the value of SwitchBot thermo-hygrometer with Raspberry Pi

Introduction

This article has the same content as ** Omron Environment Sensor (BAG type) article **. This article was conducted with a ** SwitchBot temperature / humidity sensor ** with a screen display at a low price.

What is SwitchBot?

A series of home IoT devices developed by Wonderlabs Inc., a manufacturer in Shenzhen, China. This time, the temperature and humidity sensors of the above series Use the. At a low price (about 2000 yen), the multi-functionality of data acquisition and screen display using smartphone apps and APIs is attractive.

Things necessary

** ・ RaspberryPi ** (Pi3Model B is used this time) **-Python execution environment ** (This time, pyenv uses Python 3.7.6) ** ・ SwitchBot temperature / humidity sensor **

procedure

** ① Check the Bluetooth connection between the Raspberry Pi and the sensor ** ** ② Get sensor measurements in Python ** ** ③ Hit the GAS API from Python to write data to the spreadsheet ** ** ④ Script execution regularly **

I referred to this. https://qiita.com/warpzone/items/11ec9bef21f5b965bce3

① Check the Bluetooth connection between the Raspberry pi and the sensor

Sensor recognition confirmation

** ・ Sensor setup ** Insert AAA batteries in the sensor

**-Scan for Bluetooth devices ** After checking the MAC address on SwitchBot Official App Execute the following command on Raspberry Pi

sudo hcitool lescan

LE Scan ...
AA:EE:BB:DD:55:77 (unknown)

If the MAC address confirmed by the application above appears, it is successful.

** ② Get sensor measurements in Python **

Recognition confirmation with bluepy

bluepy is a library for accessing Bluetooth Low Energy (BLE) in Python (class definition)

** ・ Installation of required packages ** Install the following

sudo install libglib2.0-dev

** ・ Install bluepy **

Install with pip with the following command

pip install bluepy

** ・ Grant permissions to bluepy ** You need to give bluepy Sudo privileges for scanning.

Go to the folder where bluepy is installed and

cd ~.pyenv/versions/3.7.6/lib/python3.7/site-packages/bluepy

• The above is when Python 3.7.6 is installed with pyenv. Please note that the location varies depending on the environment

Grant Sudo privileges to bluepy-helper with the following command

sudo setcap 'cap_net_raw,cap_net_admin+eip' bluepy-helper

Creating a sensor value acquisition script

Create the following script to get the sensor value

switchbot.py

from bluepy import btle
import struct

#Broadcast data acquisition delegate
class SwitchbotScanDelegate(btle.DefaultDelegate):
    #constructor
    def __init__(self, macaddr):
        btle.DefaultDelegate.__init__(self)
        #Variables for holding sensor data
        self.sensorValue = None
        self.macaddr = macaddr

    #Scan handler
    def handleDiscovery(self, dev, isNewDev, isNewData):
        #If you find a device with the target Mac address
        if dev.addr == self.macaddr:
            #Extract advertisement data
            for (adtype, desc, value) in dev.getScanData():  
                #Data retrieval is executed when the environment sensor is used.
                if desc == '16b Service Data':
                    #Extract sensor data
                    self._decodeSensorData(value)

    #Extract sensor data and convert to dict format
    def _decodeSensorData(self, valueStr):
        #Sensor data from character strings(4th and subsequent characters)Only take out and convert to binary
        valueBinary = bytes.fromhex(valueStr[4:])
        #Convert binary sensor data to numbers
        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
        #Store in dict type
        self.sensorValue = {
            'SensorType': 'SwitchBot',
            'Temperature': temp,
            'Humidity': humid,
            'BatteryVoltage': batt
        }

Same as the Omron environment sensor BAG version, the sensor value is acquired in the broadcast mode. Since the acquired data content was complicated, the above reference

Create main script

Create a main script to call the sensor value acquisition script

switchbot_toSpreadSheet.py

from bluepy import btle
from switchbot import SwitchbotScanDelegate

######Get the value of SwitchBot######
#switchbot.Set the sensor value acquisition delegate of py to execute at scan time
scanner = btle.Scanner().withDelegate(SwitchbotScanDelegate())
#Scan to get sensor value (timeout 5 seconds)
scanner.scan(5.0)
#Display the temperature as a trial
print(scanner.delegate.sensorValue['Temperature'])

#Describe the process of uploading to Google Spreadsheet in ④

Try running from the console

python switchbot_toSpreadSheet.py
25.49

You have now obtained the sensor readings in Python.

③ Hit the GAS API from Python to write data to the spreadsheet

[Omron Environment Sensor Article](https://qiita.com/c60evaporator/items/ed2ffde4c87001111c12#python%E3%81%8B%E3%82%89gas%E3%81%AEapi%E3%82%92%E5% 8F% A9% E3% 81% 84% E3% 81% A6% E3% 82% B9% E3% 83% 97% E3% 83% AC% E3% 83% 83% E3% 83% 89% E3% 82% B7% E3% 83% BC% E3% 83% 88% E3% 81% AB% E3% 83% 87% E3% 83% BC% E3% 82% BF% E6% 9B% B8% E3% 81% 8D% E8% BE% BC% E3% 81% BF) Please refer

④ Periodic execution of script

[Omron Environment Sensor Article](https://qiita.com/c60evaporator/items/ed2ffde4c87001111c12#%E3%82%B9%E3%82%AF%E3%83%AA%E3%83%97%E3%83 % 88% E3% 81% AE% E5% AE% 9A% E6% 9C% 9F% E5% AE% 9F% E8% A1% 8C) Please refer