[PYTHON] Notify LINE of body temperature from BLE thermometer with Raspberry Pi # 1

Introduction

Because of the corona sickness, I measure my body temperature every day. I tried to hack the thermometer because it was troublesome to take notes of body temperature one by one and GW was just free time.

: o: The following is written: o:

--How to use gatttool on Raspberry Pi --BLE with python with Raspberry Pi --GATT's Health Thermometer service

: x: I didn't write the following: x:

――In the first place, what is BLE, what is GATT, etc.

What thing?

** Notify LINE when your body temperature is measured. ** **

** Thermometer-> BLE-> Raspberry Pi-> WebAPI-> LINE-> Smartphone and send measured values. ** **

** Notifications will be sent even if the thermometer and smartphone are physically separated, so I think it would be possible to remotely grasp the temperature of a person in another location or the grandmother at home. ** **

environment

--Raspberry Pi: [Raspberry Pi 3 Model b +](https://www.amazon.co.jp/RS%E3%82%B3%E3%83%B3%E3%83%9D%E3%83%BC%E3 % 83% 8D% E3% 83% B3% E3% 83% 88Raspberry-Pi-3-B-% E3% 83% 9E% E3% 82% B6% E3% 83% BC% E3% 83% 9C% E3% 83% BC% E3% 83% 89 / dp / B07BFH96M3) --Raspberry Pi OS: Raspbian Buster with desktop 4.19

• Python 3.7.3
• blueman stable,now 2.0.8-1+b2 armhf
• bluepy 1.3.0 -[A & D Bluetooth Built-in Thermometer UT-201BLE](https://www.amazon.co.jp/AD-Bluetooth%E5%86%85%E8%94%B5-%E4%BD%93%E6%B8% A9% E8% A8% 88-UT-201BLE / dp / B00ZQMNV94)

Start from the state set up so far

--Wifi connected --Google Japanese input "Mozc" installed --Reference: Enable Japanese input for Raspberry Pi 3

About the thermometer

The thermometer is [A & D Bluetooth built-in thermometer UT-201BLE](https://www.amazon.co.jp/AD-Bluetooth%E5%86%85%E8%94%B5-%E4%BD%93%E6%B8 % A9% E8% A8% 88-UT-201BLE / dp / B00ZQMNV94) is used. This thermometer implements BLE's ** GATT (Generic attribute profile) **, a world standard interface specification. The interface is open to the public at the following sites.

• GATT
• GATT Services
• GATT Characteristics
• Health Thermometer
• Temperature Measurement

The operating procedure is as follows.

--Pair the host with the thermometer. ――You only have to do it the first time. --When the body temperature is measured, the measured value is automatically sent to the host. --If you try to send for a certain period of time and cannot send, it will be sent together at the next transmission. --Since it has a built-in clock, it also sends the measurement time.

In this case, the host is Raspberry Pi.

Pair the thermometer and Raspberry Pi

Pair the thermometer and Raspberry Pi.

① First, insert blueman.

$ sudo apt-get install blueman
$ reboot

(2) When you restart, the number of icons will increase, so pair from here.

③ Pair with the wizard from "Set up a new device".

④ If pairing is successful, a key-like mark will be displayed on the upper left of the device. This is OK.

** This was a mystery after all, but the pairing fails. After doing so many times, I was finally able to pair. Maybe it's just my environment. Please note that if you do not pair and the key mark is not attached as shown in ④, a strange error will occur somewhere in the subsequent work. ** **

Confirmation of BLE

I will confirm it because it is not a program at once, but it can be done easily as a study.

hcitool

First, let's scan the advice packet sent by the thermometer. There is ** hcitool **, which can be used to scan advertisement packets for BLE devices.

Execute the following command.

$ sudo hcitool lescan

The command scans nearby BLE devices that are advertising. If you put the thermometer in pairing mode in this state, you can check the advice packet. The BLE address of my thermometer was 18: 93: D7: 76: C9: B8.

$ sudo hcitool lescan
LE Scan ...
5A:60:E6:D4:EF:94 (unknown)
5F:C1:20:2B:BE:60 (unknown)
5F:C1:20:2B:BE:60 AQtGSk1xNFF0YQ
18:93:D7:76:C9:B8 A&D_UT201BLE_76C9B8 ← This!

gatttool

Next, try connecting to the thermometer with ** gatttool **. gatttool is a tool to talk to BLE devices with GATT. Specify the BLE address with -b and execute.

$ gatttool -b xx:xx:xx:xx:xx:xx -I

When executed with -I, it waits for command input in interactive mode. Connect with the connect command. Quickly measure your body temperature and put the thermometer in transmit mode. When connected to a thermometer, it becomes ** Connection successful **.

By the way, the transmission mode of the thermometer will be forcibly terminated in about 1 minute, so if it expires, measure the body temperature again and switch to the transmission mode. This is sober and annoying, but it can't be helped because it's a device specification ...

$ gatttool -b 18:93:D7:76:C9:B8 -I
[18:93:D7:76:C9:B8][LE]> connect
Attempting to connect to 18:93:D7:76:C9:B8
Connection successful

After connecting, use the primary command to see the UUID of the service that the thermometer has.

[18:93:D7:76:C9:B8][LE]> primary
attr handle: 0x0001, end grp handle: 0x000b uuid: 00001800-0000-1000-8000-00805f9b34fb
attr handle: 0x000c, end grp handle: 0x000f uuid: 00001801-0000-1000-8000-00805f9b34fb
attr handle: 0x0010, end grp handle: 0x0017 uuid: 00001809-0000-1000-8000-00805f9b34fb
attr handle: 0x0018, end grp handle: 0x0028 uuid: 0000180a-0000-1000-8000-00805f9b34fb
attr handle: 0x0029, end grp handle: 0x002b uuid: 0000180f-0000-1000-8000-00805f9b34fb
attr handle: 0x002c, end grp handle: 0xffff uuid: 233bf000-5a34-1b6d-975c-000d5690abe4

You can find out what these UUIDs are by looking at the GATT site.

Important is the ** 1809 ** Health Thermometer Service **.

Use the char-desc command to see the characteristics of the Health Thermometer service.

For char-desc, specify the handle (attire handle and grp handle values) of the Health Thermometer service.

Also, the UUID will come out in a row.

[18:93:D7:76:C9:B8][LE]> char-desc 0x0010 0x0017
handle: 0x0010, uuid: 00002800-0000-1000-8000-00805f9b34fb
handle: 0x0011, uuid: 00002803-0000-1000-8000-00805f9b34fb
handle: 0x0012, uuid: 00002a1c-0000-1000-8000-00805f9b34fb
handle: 0x0013, uuid: 00002902-0000-1000-8000-00805f9b34fb
handle: 0x0014, uuid: 00002803-0000-1000-8000-00805f9b34fb
handle: 0x0015, uuid: 00002a1d-0000-1000-8000-00805f9b34fb
handle: 0x0016, uuid: 00002803-0000-1000-8000-00805f9b34fb
handle: 0x0017, uuid: 00002a08-0000-1000-8000-00805f9b34fb

Check the GATT site.

The following two are important here.

• 2a1c - Temperature Measurement --Characteristic of measurement result. Indicate type, that is, the type that sends data.
• 2902 - Descriptor --A descriptor, which is an additional attribute of 2a1c. Specifically, it has a flag to turn on Indicate and start data transmission. --You can read the settings or write them to change the settings.

In short, ** If you set Descriptor to "Start sending", Temperature Measurement will send data **.

let's do it.

First, try reading the Descriptor settings. The char-read-hnd command reads the characteristic value. Specify the Handle value of Descriptor in the argument.

[18:93:D7:76:C9:B8][LE]> char-read-hnd 0x0013
Characteristic value/descriptor: 00 00 

The value is ** 00 00 **. This means that Indicate is OFF.

The value of Descriptor is

-** 0100 ** → Enable Notify -** 0200 ** → Enable Indicate

is what it means. Temperature Measurement is Indicate, which is determined by the GATT specifications, so you can set it to ** 0200 **.

To write the setting value, hit char-write-req. Specify the Handle value of Descriptor and the setting value ** 0200 ** as arguments.

[18:93:D7:76:C9:B8][LE]> char-write-req 0x0013 0200
Characteristic value was written successfully
Indication   handle = 0x0012 value: 06 73 01 00 ff e4 07 05 02 0a 28 13 02 

If all goes well, Indicate will start and data will flow from handle = 0x0012.

handle = 0x0012 means ** 2a1c --Temperature Measurement **.

The story of gatttool has become long, so I will summarize it.

#Start gatttool
$ gatttool -b xx:xx:xx:xx:xx:xx -I

#Connect with device
> connect

#Get service UUID list
> primary

#Get a characteristic list
> char-desc start handle end handle

#Read the characteristic value
> char-read-hnd handle

#Write a characteristic value
> char-write-req handle data

After measuring the body temperature, you can get the measured value with the following command.

$ gatttool -b 18:93:D7:76:C9:B8 -I
> connect
> char-write-req 0x0013 0200

Format of measured data

The thermometer gave me this kind of data, but what exactly is this?

06 73 01 00 ff e4 07 05 02 0a 28 13 02

The format of the data is written here.

Temperature Measurement

It's really hard to understand, so I'll rewrite it.

Temperature Measurement

Try to parse the received data.

C1 is 4 bytes of data and is in ** IEEE 11073 32bit float ** format. For a detailed explanation of this format, refer to the following site.

-Handling binary data with JavaScript ~ IEEE-754 and IEEE-11073 floating point ~ (2/3) -[Communicate with thermometer and sphygmomanometer with BLE GATT with Windows desktop app]([https://qiita.com/gebo/items/41da7474936845d77d06#4temperature-measurement%E3%81%AE%E3%82%A4%] E3% 83% 99% E3% 83% B3% E3% 83% 88% E3% 81% A7% E4% BD% 93% E6% B8% A9% E6% B8% AC% E5% AE% 9A% E5% 80% A4% E3% 82% 92% E5% 8F% 96% E5% BE% 97](https://qiita.com/gebo/items/41da7474936845d77d06#4take thermometer measurement at temperature-measurement event))

• to_float_from_11073_32bit_float.py

result

--Body temperature = 36.1 ℃ --Measurement date and time = 2020/5/2 10:40:19

It turned out that it is the data. The body temperature and the measured date and time are properly taken. feel well.

Thank you for your support

This time it's up to here because it's sharp.

Continue to # 2 to notify LINE of body temperature from BLE thermometer with Raspberry Pi