The Hexiwear (see “Hexiwear: Teardown of the Hackable ‘Do-Anything’ Device“) is a small and portable sensor node with built-in BLE (Bluetooth Low Energy) transceiver. In a research project we try to use multiple Hexiwear in a classroom environment and to collect sensor data on a Raspberry Pi. The Raspberry Pi 3 Model B running Linux has an on-board BLE transceiver too, so why not binding them (wirelessly) together?
Raspberry Pi 3 connected with Hexiwear over BLE
Well, things seemed easy at the beginning, and as always, there are many things to learn on a journey like this…
Outline
As always, things seem to be rather simple at the start, and the feeling is that ‘someone else must already have done this’. And as many other times, such an assumption turns out to be wrong. Well, that part was not really considered as part of the research project: now how to pair a Hexiwear with a Raspberry Pi has become a research project in a research project ;-).
In this article I describe my journey and the steps I have explored how to pair the Hexiwear and a Raspberry Pi 3 Model B together. This requires downloading BlueZ (a Bluetooth stack) for Linx, building and installing the BlueZ software on the Raspberry. I describe the needed settings on the Hexiwear and how to use the command line tools on the Raspberry to pair and explore the Hexiwear, including the necessary steps for authentication. The tutorial shows using the ‘bluetoothctl’ tool and finally using the ‘gatttool’. With this I was able to read sensor values or to trigger notifications sent from the Hexiwear to the Raspberry Pi.
💡 What does not work at this time is to use the Alert/Notification service (e.g. to write the current date/time to the Hexiwear).
Versions Used
I’m using the following versions on the Hexiwear:
- KW40 Firmware version 1.0.0
- MK64 FW version 1.0.2
- Hardware version 1.0.0
Hexiwear KW40 Firmware Version
The Raspberry Pi 3 Model B V1.2 with on-board BLE transceiver and running Raspbian GNU/Linux 8 (jessie) version 8.
Raspberry Pi 3 Model B v1.2
As Bluetooth stack (BlueZ) I have used V5.43
Download source code
See https://learn.adafruit.com/install-bluez-on-the-raspberry-pi/installation for more details about the steps needed. I have listed the short steps:
Get a link to latests version of BlueZ from http://www.bluez.org/download/ and download it:
wget http://www.kernel.org/pub/linux/bluetooth/bluez-5.43.tar.xz
Then unpack it with
tar xvf bluez-5.43.tar.xz
change the directory:
cd bluez-5.43/
Then copy the needed packages:
sudo apt-get update sudo apt-get install -y libusb-dev libdbus-1-dev libglib2.0-dev libudev-dev libical-dev libreadline-dev
then build BlueZ with the standard configuration:
./configure
This should create a configuration, with no errors. If there are errors, probably something went wrong with the above dependencies and library installation.
Start the compilation with the standard make:
make
This takes about 20 minutes to build. Then install it with
sudo make install
Starting/Stop/Enable/Disable service
As the system service on disk has changed with our build, reload the service with
sudo systemctl daemon-reload
Use the following to start or stop the service:
sudo systemctl start bluetooth
sudo systemctl stop bluetooth
The following is used to get the status of the service:
systemctl status bluetooth
To automatically turn on the service at the system startup use
sudo systemctl enable bluetooth
This can be disabled again with
sudo systemctl disable bluetooth
Enable BLE Features
To enable the BLE features, the ‘experimental’ mode needs to be turned on in the service configuration. For this edit the file with
sudo nano /lib/systemd/system/bluetooth.service
with adding ‘–experimental’ to the following line:
ExecStart=/usr/local/libexec/bluetooth/bluetoothd --experimental
As we changed the service settings, use the following to restart it
sudo systemctl daemon-reload sudo systemctl restart bluetooth
Preparing the Hexiwear for Pairing
Turn on Bluetooth on the Hexiwear. This is under Menu > Settings Bluetooth. The Bluetooth icons shall be blue to show that Bluetooth is turned ON:
Hexiwear Bluetooth Turned On
Before trying to connect to the Hexiwear, make sure you are not *already* connected. I lost hours because the Hexiwear was still connected to my mobile phone :-(. On the Hexiwear, make sure that on the main menu the Bluetooth icon is white (NOT blue!):
Hexiwear no Bluetooth Connection
Using bluetoothctl
‘bluetoothctl’ is a command line utility to manage, scan and connect to Bluetooth devices. Start the tool with
bluetoothctl
First, power off the Bluetooth host controller on the Raspberry with the ‘power off’ command:
[bluetooth]# power off Changing power off succeeded [CHG] Controller B8:27:EB:20:B7:23 Powered: no [CHG] Controller B8:27:EB:20:B7:23 Discovering: no
Then power it on again with ‘power on’:
[bluetooth]# power on Changing power on succeeded [CHG] Controller B8:27:EB:20:B7:23 Powered: yes
Then turn on the agent (which is used to ask for the pairing pin code) the the ‘agent on’ command, followed by ‘default-agent’ to enable the default pin agent:
[bluetooth]# agent on Agent registered [bluetooth]# default-agent Default agent request successful
Then start scanning for devices using the ‘scan on’ command:
[bluetooth]# scan on Discovery started [CHG] Controller B8:27:EB:20:B7:23 Discovering: yes [CHG] Device 00:32:40:08:00:12 RSSI: -62 [CHG] Device 7A:E1:8C:61:25:E4 RSSI: -44
After a while, it should show the Hexiwear, e.g.
New Hexiwear detected
[NEW] Device 00:34:40:0A:00:4E HEXIWEAR
If the Hexiwear does not show up, try a reset of the Hexiwear with Bluetooth on the Hexiwear enabled.
Stope the scanning with:
scan off
With
info 00:34:40:0A:00:4E
I get information about the device:
[bluetooth]# info 00:34:40:0A:00:4E Device 00:34:40:0A:00:4E Name: HEXIWEAR Alias: HEXIWEAR Paired: no Trusted: no Blocked: no Connected: no LegacyPairing: no
With the ‘pair’ command I make a pairing with the device:
pair 00:34:40:0A:00:4E
The Hexiwear should now show a pairing pin code like this:
Note: According to a community article I should be asked to enter a pin (displayed on the Hexiwear). However, with the BlueZ 5.43 I have not been asked for a pin initially. I can pair/bind without a pin, but then I only can read values which do not need authentication, so pairing is pretty much useless :-(. If you don’t get asked for a pairing/bonding pin, repeat carefully the steps above, including a) disconnecting from a connected Hexiwear (disconnect command), removing a Hexiwear (remove command) and make sure you quit and restart the bluetootctl program.
Bonding/Pairing Code on Hexiwear
The agent will ask for that key:
[agent] Enter passkey (number in 0-999999): 900112 [CHG] Device 00:32:40:08:00:12 Paired: yes Pairing successful
Pairing with Hexiwear
Success! I have paired the Raspberry Pi and the Hexiwear over BLE! 🙂 Below the full sequence again:
Successful Hexiwear Pairing
With the ‘info’ command it shows now paired, trusted and connected:
[HEXIWEAR]# info 00:32:40:08:00:12 Device 00:32:40:08:00:12 Name: HEXIWEAR Alias: HEXIWEAR Appearance: 0x0380 Paired: yes Trusted: yes Blocked: no Connected: yes LegacyPairing: no UUID: Generic Access Profile (00001800-0000-1000-8000-00805f9b34fb) UUID: Generic Attribute Profile (00001801-0000-1000-8000-00805f9b34fb) UUID: Device Information (0000180a-0000-1000-8000-00805f9b34fb) UUID: Battery Service (0000180f-0000-1000-8000-00805f9b34fb) UUID: Unknown (00002000-0000-1000-8000-00805f9b34fb) UUID: Unknown (00002010-0000-1000-8000-00805f9b34fb) UUID: Unknown (00002020-0000-1000-8000-00805f9b34fb) UUID: Unknown (00002030-0000-1000-8000-00805f9b34fb) UUID: Unknown (00002040-0000-1000-8000-00805f9b34fb) UUID: Vendor specific (01ff5550-ba5e-f4ee-5ca1-eb1e5e4b1ce0)
Go back in the menu on the Hexiwear, and you should see now the Bluetooth icon in blue:
Paired Bluetooth Devices
The devices command should now list the Hexiwear:
[bluetooth]# devices Device 00:34:40:0A:00:4E HEXIWEAR
Services, Descriptors and Characteristics
With the first pairing, it will report a lot of information about the device services, characteristics and descriptors. I need the service, descriptor and characteristics information to read/write values on the BLE device:
[NEW] Primary Service /org/bluez/hci0/dev_00_34_40_0A_00_4E/service0004 00001801-0000-1000-8000-00805f9b34fb Generic Attribute Profile [NEW] Characteristic /org/bluez/hci0/dev_00_34_40_0A_00_4E/service0004/char0005 00002a05-0000-1000-8000-00805f9b34fb Service Changed [NEW] Descriptor /org/bluez/hci0/dev_00_34_40_0A_00_4E/service0004/char0005/desc0007 00002902-0000-1000-8000-00805f9b34fb Client Characteristic Configuration [NEW] Primary Service /org/bluez/hci0/dev_00_34_40_0A_00_4E/service0013 01ff5550-ba5e-f4ee-5ca1-eb1e5e4b1ce0 Vendor specific [NEW] Characteristic /org/bluez/hci0/dev_00_34_40_0A_00_4E/service0013/char0014 01ff5551-ba5e-f4ee-5ca1-eb1e5e4b1ce0 Vendor specific [NEW] Descriptor /org/bluez/hci0/dev_00_34_40_0A_00_4E/service0013/char0014/desc0016 00002902-0000-1000-8000-00805f9b34fb Client Characteristic Configuration [NEW] Characteristic /org/bluez/hci0/dev_00_34_40_0A_00_4E/service0013/char0017 01ff5552-ba5e-f4ee-5ca1-eb1e5e4b1ce0 Vendor specific [NEW] Characteristic /org/bluez/hci0/dev_00_34_40_0A_00_4E/service0013/char0019 01ff5553-ba5e-f4ee-5ca1-eb1e5e4b1ce0 Vendor specific [NEW] Primary Service /org/bluez/hci0/dev_00_34_40_0A_00_4E/service001c 0000180a-0000-1000-8000-00805f9b34fb Device Information [NEW] Characteristic /org/bluez/hci0/dev_00_34_40_0A_00_4E/service001c/char001d 00002a29-0000-1000-8000-00805f9b34fb Manufacturer Name String [NEW] Characteristic /org/bluez/hci0/dev_00_34_40_0A_00_4E/service001c/char001f 00002a26-0000-1000-8000-00805f9b34fb Firmware Revision String [NEW] Characteristic /org/bluez/hci0/dev_00_34_40_0A_00_4E/service001c/char0021 00002a25-0000-1000-8000-00805f9b34fb Serial Number String [NEW] Primary Service /org/bluez/hci0/dev_00_34_40_0A_00_4E/service0026 0000180f-0000-1000-8000-00805f9b34fb Battery Service [NEW] Characteristic /org/bluez/hci0/dev_00_34_40_0A_00_4E/service0026/char0027 00002a19-0000-1000-8000-00805f9b34fb Battery Level [NEW] Descriptor /org/bluez/hci0/dev_00_34_40_0A_00_4E/service0026/char0027/desc0029 00002904-0000-1000-8000-00805f9b34fb Characteristic Format [NEW] Descriptor /org/bluez/hci0/dev_00_34_40_0A_00_4E/service0026/char0027/desc002a 00002902-0000-1000-8000-00805f9b34fb Client Characteristic Configuration [NEW] Primary Service /org/bluez/hci0/dev_00_34_40_0A_00_4E/service002e 00002000-0000-1000-8000-00805f9b34fb Unknown [NEW] Characteristic /org/bluez/hci0/dev_00_34_40_0A_00_4E/service002e/char002f 00002001-0000-1000-8000-00805f9b34fb Unknown [NEW] Characteristic /org/bluez/hci0/dev_00_34_40_0A_00_4E/service002e/char0033 00002002-0000-1000-8000-00805f9b34fb Unknown [NEW] Characteristic /org/bluez/hci0/dev_00_34_40_0A_00_4E/service002e/char0037 00002003-0000-1000-8000-00805f9b34fb Unknown [NEW] Primary Service /org/bluez/hci0/dev_00_34_40_0A_00_4E/service003d 00002010-0000-1000-8000-00805f9b34fb Unknown [NEW] Characteristic /org/bluez/hci0/dev_00_34_40_0A_00_4E/service003d/char003e 00002011-0000-1000-8000-00805f9b34fb Unknown [NEW] Characteristic /org/bluez/hci0/dev_00_34_40_0A_00_4E/service003d/char0042 00002012-0000-1000-8000-00805f9b34fb Unknown [NEW] Characteristic /org/bluez/hci0/dev_00_34_40_0A_00_4E/service003d/char0046 00002013-0000-1000-8000-00805f9b34fb Unknown [NEW] Characteristic /org/bluez/hci0/dev_00_34_40_0A_00_4E/service003d/char004a 00002014-0000-1000-8000-00805f9b34fb Unknown [NEW] Primary Service /org/bluez/hci0/dev_00_34_40_0A_00_4E/service0050 00002020-0000-1000-8000-00805f9b34fb Unknown [NEW] Characteristic /org/bluez/hci0/dev_00_34_40_0A_00_4E/service0050/char0051 00002021-0000-1000-8000-00805f9b34fb Unknown [NEW] Characteristic /org/bluez/hci0/dev_00_34_40_0A_00_4E/service0050/char0055 00002022-0000-1000-8000-00805f9b34fb Unknown [NEW] Characteristic /org/bluez/hci0/dev_00_34_40_0A_00_4E/service0050/char0059 00002023-0000-1000-8000-00805f9b34fb Unknown [NEW] Primary Service /org/bluez/hci0/dev_00_34_40_0A_00_4E/service005f 00002030-0000-1000-8000-00805f9b34fb Unknown [NEW] Characteristic /org/bluez/hci0/dev_00_34_40_0A_00_4E/service005f/char0060 00002031-0000-1000-8000-00805f9b34fb Unknown [NEW] Characteristic /org/bluez/hci0/dev_00_34_40_0A_00_4E/service005f/char0064 00002032-0000-1000-8000-00805f9b34fb Unknown [NEW] Descriptor /org/bluez/hci0/dev_00_34_40_0A_00_4E/service005f/char0064/desc0067 00002902-0000-1000-8000-00805f9b34fb Client Characteristic Configuration [NEW] Primary Service /org/bluez/hci0/dev_00_34_40_0A_00_4E/service006b 00002040-0000-1000-8000-00805f9b34fb Unknown [NEW] Characteristic /org/bluez/hci0/dev_00_34_40_0A_00_4E/service006b/char006c 00002041-0000-1000-8000-00805f9b34fb Unknown [NEW] Descriptor /org/bluez/hci0/dev_00_34_40_0A_00_4E/service006b/char006c/desc006f 00002902-0000-1000-8000-00805f9b34fb Client Characteristic Configuration [CHG] Device 00:34:40:0A:00:4E UUIDs: 00001800-0000-1000-8000-00805f9b34fb [CHG] Device 00:34:40:0A:00:4E UUIDs: 00001801-0000-1000-8000-00805f9b34fb [CHG] Device 00:34:40:0A:00:4E UUIDs: 0000180a-0000-1000-8000-00805f9b34fb [CHG] Device 00:34:40:0A:00:4E UUIDs: 0000180f-0000-1000-8000-00805f9b34fb [CHG] Device 00:34:40:0A:00:4E UUIDs: 00002000-0000-1000-8000-00805f9b34fb [CHG] Device 00:34:40:0A:00:4E UUIDs: 00002010-0000-1000-8000-00805f9b34fb [CHG] Device 00:34:40:0A:00:4E UUIDs: 00002020-0000-1000-8000-00805f9b34fb [CHG] Device 00:34:40:0A:00:4E UUIDs: 00002030-0000-1000-8000-00805f9b34fb [CHG] Device 00:34:40:0A:00:4E UUIDs: 00002040-0000-1000-8000-00805f9b34fb [CHG] Device 00:34:40:0A:00:4E UUIDs: 01ff5550-ba5e-f4ee-5ca1-eb1e5e4b1ce0 [CHG] Device 00:34:40:0A:00:4E ServicesResolved: yes [CHG] Device 00:34:40:0A:00:4E Appearance: 0x0380 [HEXIWEAR]#
With the device paired, I can inspect the device with
info 00:34:40:0A:00:4E
which gives me a list of UUID’s:
Device 00:34:40:0A:00:4E Name: HEXIWEAR Alias: HEXIWEAR Appearance: 0x0380 Paired: no Trusted: yes Blocked: no Connected: yes LegacyPairing: no UUID: Generic Access Profile (00001800-0000-1000-8000-00805f9b34fb) UUID: Generic Attribute Profile (00001801-0000-1000-8000-00805f9b34fb) UUID: Device Information (0000180a-0000-1000-8000-00805f9b34fb) UUID: Battery Service (0000180f-0000-1000-8000-00805f9b34fb) UUID: Unknown (00002000-0000-1000-8000-00805f9b34fb) UUID: Unknown (00002010-0000-1000-8000-00805f9b34fb) UUID: Unknown (00002020-0000-1000-8000-00805f9b34fb) UUID: Unknown (00002030-0000-1000-8000-00805f9b34fb) UUID: Unknown (00002040-0000-1000-8000-00805f9b34fb) UUID: Vendor specific (01ff5550-ba5e-f4ee-5ca1-eb1e5e4b1ce0)
With
list-attributes 00:34:40:0A:00:4E
I can get again the list of services, characteristics and descriptors from above:
Primary Service /org/bluez/hci0/dev_00_34_40_0A_00_4E/service0004 00001801-0000-1000-8000-00805f9b34fb Generic Attribute Profile Characteristic /org/bluez/hci0/dev_00_34_40_0A_00_4E/service0004/char0005 00002a05-0000-1000-8000-00805f9b34fb Service Changed Descriptor /org/bluez/hci0/dev_00_34_40_0A_00_4E/service0004/char0005/desc0007 00002902-0000-1000-8000-00805f9b34fb Client Characteristic Configuration Primary Service /org/bluez/hci0/dev_00_34_40_0A_00_4E/service0013 01ff5550-ba5e-f4ee-5ca1-eb1e5e4b1ce0 Vendor specific Characteristic /org/bluez/hci0/dev_00_34_40_0A_00_4E/service0013/char0014 01ff5551-ba5e-f4ee-5ca1-eb1e5e4b1ce0 Vendor specific Descriptor /org/bluez/hci0/dev_00_34_40_0A_00_4E/service0013/char0014/desc0016 00002902-0000-1000-8000-00805f9b34fb Client Characteristic Configuration Characteristic /org/bluez/hci0/dev_00_34_40_0A_00_4E/service0013/char0017 01ff5552-ba5e-f4ee-5ca1-eb1e5e4b1ce0 Vendor specific Characteristic /org/bluez/hci0/dev_00_34_40_0A_00_4E/service0013/char0019 01ff5553-ba5e-f4ee-5ca1-eb1e5e4b1ce0 Vendor specific Primary Service /org/bluez/hci0/dev_00_34_40_0A_00_4E/service001c 0000180a-0000-1000-8000-00805f9b34fb Device Information Characteristic /org/bluez/hci0/dev_00_34_40_0A_00_4E/service001c/char001d 00002a29-0000-1000-8000-00805f9b34fb Manufacturer Name String Characteristic /org/bluez/hci0/dev_00_34_40_0A_00_4E/service001c/char001f 00002a26-0000-1000-8000-00805f9b34fb Firmware Revision String Characteristic /org/bluez/hci0/dev_00_34_40_0A_00_4E/service001c/char0021 00002a25-0000-1000-8000-00805f9b34fb Serial Number String Primary Service /org/bluez/hci0/dev_00_34_40_0A_00_4E/service0026 0000180f-0000-1000-8000-00805f9b34fb Battery Service Characteristic /org/bluez/hci0/dev_00_34_40_0A_00_4E/service0026/char0027 00002a19-0000-1000-8000-00805f9b34fb Battery Level Descriptor /org/bluez/hci0/dev_00_34_40_0A_00_4E/service0026/char0027/desc0029 00002904-0000-1000-8000-00805f9b34fb Characteristic Format Descriptor /org/bluez/hci0/dev_00_34_40_0A_00_4E/service0026/char0027/desc002a 00002902-0000-1000-8000-00805f9b34fb Client Characteristic Configuration Primary Service /org/bluez/hci0/dev_00_34_40_0A_00_4E/service002e 00002000-0000-1000-8000-00805f9b34fb Unknown Characteristic /org/bluez/hci0/dev_00_34_40_0A_00_4E/service002e/char002f 00002001-0000-1000-8000-00805f9b34fb Unknown Characteristic /org/bluez/hci0/dev_00_34_40_0A_00_4E/service002e/char0033 00002002-0000-1000-8000-00805f9b34fb Unknown Characteristic /org/bluez/hci0/dev_00_34_40_0A_00_4E/service002e/char0037 00002003-0000-1000-8000-00805f9b34fb Unknown Primary Service /org/bluez/hci0/dev_00_34_40_0A_00_4E/service003d 00002010-0000-1000-8000-00805f9b34fb Unknown Characteristic /org/bluez/hci0/dev_00_34_40_0A_00_4E/service003d/char003e 00002011-0000-1000-8000-00805f9b34fb Unknown Characteristic /org/bluez/hci0/dev_00_34_40_0A_00_4E/service003d/char0042 00002012-0000-1000-8000-00805f9b34fb Unknown Characteristic /org/bluez/hci0/dev_00_34_40_0A_00_4E/service003d/char0046 00002013-0000-1000-8000-00805f9b34fb Unknown Characteristic /org/bluez/hci0/dev_00_34_40_0A_00_4E/service003d/char004a 00002014-0000-1000-8000-00805f9b34fb Unknown Primary Service /org/bluez/hci0/dev_00_34_40_0A_00_4E/service0050 00002020-0000-1000-8000-00805f9b34fb Unknown Characteristic /org/bluez/hci0/dev_00_34_40_0A_00_4E/service0050/char0051 00002021-0000-1000-8000-00805f9b34fb Unknown Characteristic /org/bluez/hci0/dev_00_34_40_0A_00_4E/service0050/char0055 00002022-0000-1000-8000-00805f9b34fb Unknown Characteristic /org/bluez/hci0/dev_00_34_40_0A_00_4E/service0050/char0059 00002023-0000-1000-8000-00805f9b34fb Unknown Primary Service /org/bluez/hci0/dev_00_34_40_0A_00_4E/service005f 00002030-0000-1000-8000-00805f9b34fb Unknown Characteristic /org/bluez/hci0/dev_00_34_40_0A_00_4E/service005f/char0060 00002031-0000-1000-8000-00805f9b34fb Unknown Characteristic /org/bluez/hci0/dev_00_34_40_0A_00_4E/service005f/char0064 00002032-0000-1000-8000-00805f9b34fb Unknown Descriptor /org/bluez/hci0/dev_00_34_40_0A_00_4E/service005f/char0064/desc0067 00002902-0000-1000-8000-00805f9b34fb Client Characteristic Configuration Primary Service /org/bluez/hci0/dev_00_34_40_0A_00_4E/service006b 00002040-0000-1000-8000-00805f9b34fb Unknown Characteristic /org/bluez/hci0/dev_00_34_40_0A_00_4E/service006b/char006c 00002041-0000-1000-8000-00805f9b34fb Unknown Descriptor /org/bluez/hci0/dev_00_34_40_0A_00_4E/service006b/char006c/desc006f 00002902-0000-1000-8000-00805f9b34fb Client Characteristic Configuration
Now I’m going to use that information to read and write values on the device.
Reading from Battery Service
The battery service is documented as:
Hexiwear Battery Service
It has been listed as:
Primary Service
/org/bluez/hci0/dev_00_34_40_0A_00_4E/service0026
0000180f-0000-1000-8000-00805f9b34fb
Battery Service
The characteristic is reported as:
Characteristic /org/bluez/hci0/dev_00_34_40_0A_00_4E/service0026/char0027 00002a19-0000-1000-8000-00805f9b34fb Battery Level
I can select the attribute with
select-attribute /org/bluez/hci0/dev_00_32_40_08_00_12/service0026/char0027
💡 Use <tab> key to autocomplete the values.
and then use the following command:
read
Reading Attribute Value
It reports 0x64 (decimal 100), so my battery level is at 100% 🙂
Reading Device Information Service
Another example is to read the DIS (Device Information Service). It is documented as:
Device Information Service
The characteristic for the Manufacturer Name String is listed as:
Characteristic /org/bluez/hci0/dev_00_34_40_0A_00_4E/service001c/char001d 00002a29-0000-1000-8000-00805f9b34fb Manufacturer Name String
I select the attribute
select-attribute /org/bluez/hci0/dev_00_34_40_0A_00_4E/service001c/char001d
With
atribute-info
I get the information with the values:
[HEXIWEAR:/service001c/char001d]# attribute-info Characteristic - Manufacturer Name String UUID: 00002a29-0000-1000-8000-00805f9b34fb Service: /org/bluez/hci0/dev_00_32_40_08_00_12/service001c Value: 0x4d Value: 0x69 Value: 0x6b Value: 0x72 Value: 0x6f Value: 0x65 Value: 0x6c Value: 0x65 Value: 0x6b Value: 0x74 Value: 0x72 Value: 0x6f Value: 0x6e Value: 0x69 Value: 0x6b Value: 0x61 Flags: read
Or I can read it with the ‘read’ command:
[HEXIWEAR:/service001c/char001d]# read Attempting to read /org/bluez/hci0/dev_00_32_40_08_00_12/service001c/char001d [CHG] Attribute /org/bluez/hci0/dev_00_32_40_08_00_12/service001c/char001d Value: 0x4d [CHG] Attribute /org/bluez/hci0/dev_00_32_40_08_00_12/service001c/char001d Value: 0x69 [CHG] Attribute /org/bluez/hci0/dev_00_32_40_08_00_12/service001c/char001d Value: 0x6b [CHG] Attribute /org/bluez/hci0/dev_00_32_40_08_00_12/service001c/char001d Value: 0x72 [CHG] Attribute /org/bluez/hci0/dev_00_32_40_08_00_12/service001c/char001d Value: 0x6f [CHG] Attribute /org/bluez/hci0/dev_00_32_40_08_00_12/service001c/char001d Value: 0x65 [CHG] Attribute /org/bluez/hci0/dev_00_32_40_08_00_12/service001c/char001d Value: 0x6c [CHG] Attribute /org/bluez/hci0/dev_00_32_40_08_00_12/service001c/char001d Value: 0x65 [CHG] Attribute /org/bluez/hci0/dev_00_32_40_08_00_12/service001c/char001d Value: 0x6b [CHG] Attribute /org/bluez/hci0/dev_00_32_40_08_00_12/service001c/char001d Value: 0x74 [CHG] Attribute /org/bluez/hci0/dev_00_32_40_08_00_12/service001c/char001d Value: 0x72 [CHG] Attribute /org/bluez/hci0/dev_00_32_40_08_00_12/service001c/char001d Value: 0x6f [CHG] Attribute /org/bluez/hci0/dev_00_32_40_08_00_12/service001c/char001d Value: 0x6e [CHG] Attribute /org/bluez/hci0/dev_00_32_40_08_00_12/service001c/char001d Value: 0x69 [CHG] Attribute /org/bluez/hci0/dev_00_32_40_08_00_12/service001c/char001d Value: 0x6b [CHG] Attribute /org/bluez/hci0/dev_00_32_40_08_00_12/service001c/char001d Value: 0x61 4d 69 6b 72 6f 65 6c 65 6b 74 72 6f 6e 69 6b 61 Mikroelektronika
Reading Values with Encryption and Authentication
The above thing work even without authentication/encryption (what we enabled with the bonding pin). Now let’s look at the motion service which has now a different security mode:
Motion Service in Hexiwear
They are listed as
[NEW] Primary Service /org/bluez/hci0/dev_00_32_40_08_00_12/service002e 00002000-0000-1000-8000-00805f9b34fb Unknown [NEW] Characteristic /org/bluez/hci0/dev_00_32_40_08_00_12/service002e/char002f 00002001-0000-1000-8000-00805f9b34fb Unknown [NEW] Characteristic /org/bluez/hci0/dev_00_32_40_08_00_12/service002e/char0033 00002002-0000-1000-8000-00805f9b34fb Unknown [NEW] Characteristic /org/bluez/hci0/dev_00_32_40_08_00_12/service002e/char0037 00002003-0000-1000-8000-00805f9b34fb Unknown
Select the attribute for the accelerometer:
select-attribute /org/bluez/hci0/dev_00_32_40_08_00_12/service002e/char002f
And when I read it:
[HEXIWEAR:/service002e/char002f]# read Attempting to read /org/bluez/hci0/dev_00_32_40_08_00_12/service002e/char002f [CHG] Attribute /org/bluez/hci0/dev_00_32_40_08_00_12/service002e/char002f Value: 0x03 [CHG] Attribute /org/bluez/hci0/dev_00_32_40_08_00_12/service002e/char002f Value: 0x00 [CHG] Attribute /org/bluez/hci0/dev_00_32_40_08_00_12/service002e/char002f Value: 0xff [CHG] Attribute /org/bluez/hci0/dev_00_32_40_08_00_12/service002e/char002f Value: 0xff [CHG] Attribute /org/bluez/hci0/dev_00_32_40_08_00_12/service002e/char002f Value: 0xa1 [CHG] Attribute /org/bluez/hci0/dev_00_32_40_08_00_12/service002e/char002f Value: 0xff 03 00 ff ff a1 ff ......
💡 if you read all zeros, make sure you have the ‘Sensor Tag’ application running on the Hexiwear.
Alert/Command Service
At the time of this article, there is only the Alert/Command service which allows writing to the Hexiwear:
Hexiwear Alert Command Service
It is listed as
[NEW] Primary Service /org/bluez/hci0/dev_00_32_40_08_00_12/service005f 00002030-0000-1000-8000-00805f9b34fb Unknown [NEW] Characteristic /org/bluez/hci0/dev_00_32_40_08_00_12/service005f/char0060 00002031-0000-1000-8000-00805f9b34fb Unknown [NEW] Characteristic /org/bluez/hci0/dev_00_32_40_08_00_12/service005f/char0064 00002032-0000-1000-8000-00805f9b34fb Unknown
Read gives
[HEXIWEAR:# read Attempting to read /org/bluez/hci0/dev_00_32_40_08_00_12/service005f/char0060 [CHG] Attribute /org/bluez/hci0/dev_00_32_40_08_00_12/service005f/char0060 Value: 0x00 [CHG] Attribute /org/bluez/hci0/dev_00_32_40_08_00_12/service005f/char0060 Value: 0x00 [CHG] Attribute /org/bluez/hci0/dev_00_32_40_08_00_12/service005f/char0060 Value: 0x00 [CHG] Attribute /org/bluez/hci0/dev_00_32_40_08_00_12/service005f/char0060 Value: 0x00 [CHG] Attribute /org/bluez/hci0/dev_00_32_40_08_00_12/service005f/char0060 Value: 0x00 [CHG] Attribute /org/bluez/hci0/dev_00_32_40_08_00_12/service005f/char0060 Value: 0x00 [CHG] Attribute /org/bluez/hci0/dev_00_32_40_08_00_12/service005f/char0060 Value: 0x00 [CHG] Attribute /org/bluez/hci0/dev_00_32_40_08_00_12/service005f/char0060 Value: 0x00 [CHG] Attribute /org/bluez/hci0/dev_00_32_40_08_00_12/service005f/char0060 Value: 0x00 [CHG] Attribute /org/bluez/hci0/dev_00_32_40_08_00_12/service005f/char0060 Value: 0x00 [CHG] Attribute /org/bluez/hci0/dev_00_32_40_08_00_12/service005f/char0060 Value: 0x00 [CHG] Attribute /org/bluez/hci0/dev_00_32_40_08_00_12/service005f/char0060 Value: 0x00 [CHG] Attribute /org/bluez/hci0/dev_00_32_40_08_00_12/service005f/char0060 Value: 0x00 [CHG] Attribute /org/bluez/hci0/dev_00_32_40_08_00_12/service005f/char0060 Value: 0x00 [CHG] Attribute /org/bluez/hci0/dev_00_32_40_08_00_12/service005f/char0060 Value: 0x00 [CHG] Attribute /org/bluez/hci0/dev_00_32_40_08_00_12/service005f/char0060 Value: 0x00 [CHG] Attribute /org/bluez/hci0/dev_00_32_40_08_00_12/service005f/char0060 Value: 0x00 [CHG] Attribute /org/bluez/hci0/dev_00_32_40_08_00_12/service005f/char0060 Value: 0x00 [CHG] Attribute /org/bluez/hci0/dev_00_32_40_08_00_12/service005f/char0060 Value: 0x00 [CHG] Attribute /org/bluez/hci0/dev_00_32_40_08_00_12/service005f/char0060 Value: 0x00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00 00 00 00 .... [HEXIWEAR:/service005f/char0060]#
Next I tried to write the date/time:
write 0x3 0x4 0x10 0x20 0x30 0x40
I tried to write the notifications with
write 0x1 0x2 0x1
Or even writing all 20 bytes:
write 0x1 0x2 0x1 0x0 0x0 0x0 0x0 0x0 0x0 0x0 0x0 0x0 0x0 0x0 0x0 0x0 0x0 0x0 0x0 0x0
But all attempts failed :-(:
Attempting to write /org/bluez/hci0/dev_00_32_40_08_00_12/service005f/char0060 Failed to write: org.bluez.Error.InProgress
So I’m not sure what I’m doing wrong? At this point, I’m not able to write to that service :-(.
UPDATE: Finally managed to write data with the gatttool, see below.
Disconnecting
Disconnect the device with
disconnect 00:32:40:08:00:12
and then leave bluetoothctl with
quit
Using the gatttool
The gatttool is another powerful tool like the bluetoothctl one. With the gatttool I can inspect the attributes.
💡 Before using the gatttool, make sure you have used the ‘disconnect’ command in the bluetoothctl, followed by ‘quit’ to exit the program, otherwise the gatttool will not work!
Run the gatttool in interactive mode:
sudo gatttool -I
and then connect to the Hexiwear with the address from above:
connect 00:32:40:08:00:12
Connecting with gatttool
Alternatively I can launch it directly with
sudo gatttool -b 00:32:40:08:00:12 -t random -I
In case of problems connecting to the device, stop and restart the bluetooth service:
sudo systemctl stop bluetooth
sudo systemctl start bluetooth
With the ‘primary’ command I list the primary services:
[00:32:40:08:00:12][LE]> primary attr handle: 0x0004, end grp handle: 0x0007 uuid: 00001801-0000-1000-8000-00805f9b34fb attr handle: 0x0009, end grp handle: 0x0011 uuid: 00001800-0000-1000-8000-00805f9b34fb attr handle: 0x0013, end grp handle: 0x001a uuid: 01ff5550-ba5e-f4ee-5ca1-eb1e5e4b1ce0 attr handle: 0x001c, end grp handle: 0x0022 uuid: 0000180a-0000-1000-8000-00805f9b34fb attr handle: 0x0026, end grp handle: 0x002a uuid: 0000180f-0000-1000-8000-00805f9b34fb attr handle: 0x002e, end grp handle: 0x0038 uuid: 00002000-0000-1000-8000-00805f9b34fb attr handle: 0x003d, end grp handle: 0x004b uuid: 00002010-0000-1000-8000-00805f9b34fb attr handle: 0x0050, end grp handle: 0x005a uuid: 00002020-0000-1000-8000-00805f9b34fb attr handle: 0x005f, end grp handle: 0x0067 uuid: 00002030-0000-1000-8000-00805f9b34fb attr handle: 0x006b, end grp handle: 0x006f uuid: 00002040-0000-1000-8000-00805f9b34fb
According to the Hexiwear BLE documentation, there is a custom motion service with UUID 0x2000:
Hexiwear Custom Motion Service
According to the information from the ‘primary’ command above, attribute handle is 0x002e with a group handle of 0x0038:
attr handle: 0x002e, end grp handle: 0x0038 uuid: 00002000-0000-1000-8000-00805f9b34fb
Both the attribute handle and the group handle can now be used with a characteristic discovery command:
char-desc 0x002e 0x0038
which gives
handle: 0x002e, uuid: 00002800-0000-1000-8000-00805f9b34fb handle: 0x002f, uuid: 00002803-0000-1000-8000-00805f9b34fb handle: 0x0030, uuid: 00002001-0000-1000-8000-00805f9b34fb handle: 0x0033, uuid: 00002803-0000-1000-8000-00805f9b34fb handle: 0x0034, uuid: 00002002-0000-1000-8000-00805f9b34fb handle: 0x0037, uuid: 00002803-0000-1000-8000-00805f9b34fb handle: 0x0038, uuid: 00002003-0000-1000-8000-00805f9b34fb
From the documentation above, there is
- 0x2001: Accelerometer
- 0x2002: Gyro
- 0x2003: Magnetometer
With this, I can read the accelerometer three 16bit values with:
char-read-uuid 0x2001
gives:
[00:32:40:08:00:12][LE]> char-read-uuid 0x2001 handle: 0x0030 value: 04 00 ff ff a2 ff
💡 if all zeros are returned, check that the Hexiwear has the sensors enabled. Turn on the ‘Sensor Tag’ application.
The values are in ‘centi-g’, therefore:
- X (0x0004): 0.04 g
- Y (0xffff): -0.01 g
- Z (0xffa2): -0.94 g
Alert Service
The information about the alert service is the following:
Hexiwear Alert Command Service
according to the ‘primary’ command, I have
attr handle: 0x005f, end grp handle: 0x0067 uuid: 00002030-0000-1000-8000-00805f9b34fb
So I check the attributes with
char-desc 0x005f 0x0067
which gives
[00:32:40:08:00:12][LE]> char-desc 0x005f 0x0067 handle: 0x005f, uuid: 00002800-0000-1000-8000-00805f9b34fb handle: 0x0060, uuid: 00002803-0000-1000-8000-00805f9b34fb handle: 0x0061, uuid: 00002031-0000-1000-8000-00805f9b34fb handle: 0x0064, uuid: 00002803-0000-1000-8000-00805f9b34fb handle: 0x0065, uuid: 00002032-0000-1000-8000-00805f9b34fb handle: 0x0067, uuid: 00002902-0000-1000-8000-00805f9b34fb
The handle is 0x0061, I read it with
char-read-hnd 0x0061
which gives
[00:32:40:08:00:12][LE]> char-read-hnd 0x0061 Characteristic value/descriptor: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
Next I tried to write a dummy date/time (0x01020304) to the handle with
[00:32:40:08:00:12][LE]> char-write-cmd 0x0061 030401020304 [00:32:40:08:00:12][LE]> char-write-req 0x0061 030401020304
💡 I have not found clear documentation about the difference between char-write-cmd and char-write-req. To me the char-write-req is expecting a response, while char-write-cmd gives no output indicating success or failure.
but both trial did nothing? Not sure what is wrong or what I should do?
All what I get is after a while:
Error: Characteristic Write Request failed: A timeout occured
I tried writing the exact 20 bytes too:
char-write-cmd 0x61 0304010203040000000000000000000000000000
But that failed as well? I even tried to send the bytes in reverse order.
So here I’m really stuck: I can read, but I cannot write the time information :-(.
💡 So far was not able to use the WireShark sniffer with encrypted traffic. Thanks to a tip from a colleague I should be able to get this worked out.
Getting Notifications
On the Hexiwear there is an application mode service:
Hexiwear Application Mode Service
This allows me to read in which mode the application is running, plus getting notifications if something has changed.
With the primary command I get a list of services handles of their ID’s. The one with 0x2040 is listed last:
[00:32:40:08:00:12][LE]> primary attr handle: 0x0004, end grp handle: 0x0007 uuid: 00001801-0000-1000-8000-00805f9b34fb attr handle: 0x0009, end grp handle: 0x0011 uuid: 00001800-0000-1000-8000-00805f9b34fb attr handle: 0x0013, end grp handle: 0x001a uuid: 01ff5550-ba5e-f4ee-5ca1-eb1e5e4b1ce0 attr handle: 0x001c, end grp handle: 0x0022 uuid: 0000180a-0000-1000-8000-00805f9b34fb attr handle: 0x0026, end grp handle: 0x002a uuid: 0000180f-0000-1000-8000-00805f9b34fb attr handle: 0x002e, end grp handle: 0x0038 uuid: 00002000-0000-1000-8000-00805f9b34fb attr handle: 0x003d, end grp handle: 0x004b uuid: 00002010-0000-1000-8000-00805f9b34fb attr handle: 0x0050, end grp handle: 0x005a uuid: 00002020-0000-1000-8000-00805f9b34fb attr handle: 0x005f, end grp handle: 0x0067 uuid: 00002030-0000-1000-8000-00805f9b34fb attr handle: 0x006b, end grp handle: 0x006f uuid: 00002040-0000-1000-8000-00805f9b34fb
With char-desc I list and limit the handles for that service. The UUID for the ‘App Mode’ characteristics is 0x2041:
[00:32:40:08:00:12][LE]> char-desc 0x6b 0x6f handle: 0x006b, uuid: 00002800-0000-1000-8000-00805f9b34fb handle: 0x006c, uuid: 00002803-0000-1000-8000-00805f9b34fb handle: 0x006d, uuid: 00002041-0000-1000-8000-00805f9b34fb handle: 0x006f, uuid: 00002902-0000-1000-8000-00805f9b34fb
I can read that value with the char-read-uuid or char-read-hnd command:
[00:32:40:08:00:12][LE]> char-read-uuid 0x2041 handle: 0x006d value: 00 [00:32:40:08:00:12][LE]> char-read-hnd 0x6d Characteristic value/descriptor: 00
This means the Hexiwear is in ‘Idle’ mode. When I start the ‘Pedometer’ application on the Hexiwear I get:
[00:32:40:08:00:12][LE]> char-read-hnd 0x6d Characteristic value/descriptor: 06
How to get notifications about the mode changed? Beside of 0x2041, there are other UUIDs:
- 0x2800: handle: 0x006b, uuid: 00002800-0000-1000-8000-00805f9b34fb
- 0x2803: handle: 0x006c, uuid: 00002803-0000-1000-8000-00805f9b34fb
- 0x2902:handle: 0x006f, uuid: 00002902-0000-1000-8000-00805f9b34fb
These are standard BLE UUIDs (with links to the GATT XML description):
- 0x2800: GATT Primary Service
- 0x2803: GATT Characteristics Declaration
- 0x2902: GATT Client Characteristics Configuration
Checking the 0x2800 (handle 0x6b) reveals the GATT Primary Service:
[00:32:40:08:00:12][LE]> char-read-hnd 0x6b Characteristic value/descriptor: 40 20
So the primary service is the UUID 0x2040 (note the conversion from big endian to little endian). The 0x2040 is the Hexiwear ‘Application Mode’ service.
Next reading the UUID 0x2803 (handle 0x6c) which provides the GATT Characteristics Declaration:
[00:32:40:08:00:12][LE]> char-read-hnd 0x6c Characteristic value/descriptor: 12 6d 00 41 20
The first byte (0x12, 0b00010010) contains information about the characteristics. Bit 1 set tells me that I can read the value and Bit 4 set tells me that I can get notifications:
GATT Characteristics Declaration
The next is a 16bit value (0x006D) which points to the characteristics value. So the handle 0x6D contains the value. This is what we used above to read the value:
handle: 0x006d, uuid: 00002041-0000-1000-8000-00805f9b34fb
The UUID 0x2902 (handle 0x6f) is the GATT Client Characteristics Configuration which allows me to configure the characteristics. Reading it gives:
[00:32:40:08:00:12][LE]> char-read-hnd 0x6f Characteristic value/descriptor: 00 00
GATT 0x2902 Value Fields
To turn on notifications, I have to write a 0x0001 to the handle:
[00:32:40:08:00:12][LE]> char-write-req 0x6f 0001 Characteristic value was written successfully
OK, seems ok, but now read back the value again:
[00:32:40:08:00:12][LE]> char-read-hnd 0x6f Characteristic value/descriptor: 00 00
So the value was not written? Ah, right, Little-Endian vs. Big Endian! Swapping the bytes does it correctly:
[00:32:40:08:00:12][LE]> char-write-req 0x6f 0100 Characteristic value was written successfully [00:32:40:08:00:12][LE]> char-read-hnd 0x6f Characteristic value/descriptor: 01 00
Now I get notifications when the application mode changes:
[00:32:40:08:00:12][LE]> char-read-hnd 0x6f Characteristic value/descriptor: 01 00 Notification handle = 0x006d value: 00 Notification handle = 0x006d value: 06 Notification handle = 0x006d value: 00 Notification handle = 0x006d value: 02 Notification handle = 0x006d value: 02 Notification handle = 0x006d value: 00 Notification handle = 0x006d value: 02 Notification handle = 0x006d value: 02
💡 Interestingly, I get two notification with value 02 when I enter the Sensor Tag Hexiwear mode.
To disable notifications I write back 0x0000 to the characteristics:
[00:32:40:08:00:12][LE]> char-write-req 0x6f 0000 Characteristic value was written successfully [00:32:40:08:00:12][LE]> char-read-hnd 0x6f Characteristic value/descriptor: 00 00
With this, I’m able to read values and turn on notifications. Still, writing the date/time is something which is missing 😦
UPDATE: with the help of a BLE sniffer (see “Tutorial: Hexiwear Bluetooth Low Energy Packet Sniffing with Wireshark“) I have found the correct sequence. To write a new date/time for example the following can be used:
char-write-req 61 030422e65a580000000000000000000000000000
Exit the gatttool with
quit
Summary
The Hexiwear is a cool BLE enabled device. Unfortunately the BLE documentation for it is very thin, and while searching the community and forums I have found many good hints, but found as well others asking the same questions I did, unanswered :-(. While I can successfully authenticate, read attributes and turn on and get notifications, I’m not yet able to write to the Hexiwear, e.g. writing the current date/time to update the Hexiwear RTC. As I’m struggling with this for more than two weeks, I make a point and have published what I know and can do. So I think I have to dig more over the coming days and weeks on that topic. On the plus side, I have learned a lot about BLE and GATT :-).
Happy Hexiwearing 🙂
Links
- Installing BlueZ on a Raspberry Pi: https://learn.adafruit.com/install-bluez-on-the-raspberry-pi
- Bluefruit LE Python Library: https://learn.adafruit.com/bluefruit-le-python-library
- Tutorial about bluetoothctl (German): https://kofler.info/bluetooth-konfiguration-im-terminal-mit-bluetoothctl/
- Freescale community post: https://community.nxp.com/thread/429169
- Hexiwear BLE specification: https://github.com/MikroElektronika/HEXIWEAR/blob/master/documentation/HEXIWEAR%20Bluetooth%20Specifications.pdf
- Connecting to BLE with Python: http://www.hexiwear.com/forums/topic/connecting-hexiwear-to-python-script-on-raspberry-pi/
- PiGATT: http://christopherpeplin.com/2015/10/22/pygatt-python-bluetooth-low-energy-ble/
- Python Scripting: http://shawnhymel.com/665/using-python-and-ble-to-receive-data-from-the-rfduino/
- Reverse Engineering a Bluetoth LW Light Bulb: https://learn.adafruit.com/reverse-engineering-a-bluetooth-low-energy-light-bulb/control-with-bluez
- Gatttool example usage: https://github.com/pcborenstein/bluezDoc/wiki/hcitool-and-gatttool-example
- Getting Started with Bluetooth Low Energy: https://www.safaribooksonline.com/library/view/getting-started-with/9781491900550/ch04.html
- Bluetooth: ATT and GATT: https://epxx.co/artigos/bluetooth_gatt.html
- Sniffing BLE Packets: Tutorial: Hexiwear Bluetooth Low Energy Packet Sniffing with Wireshark
MCU on Eclipse 
Even tho you weren’t successful with writing to the Hexiwear that’s still some damn good blog post. Big up! It kinda wants me to get one of this Hexiwear thing myself…
Gr Joe
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Hi Joe,
failure can be a success too :-). I have learned a lot, and I think I’m on a good track with reverse engineering. And if you want to try out a Hexiwear, you know where you can find me :-).
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Hello, I find your article very interesting !! I have some question. Do you think it is possible to the same thing with another device ? Like a BLE watch for exemple.
Because I can connect with the raspberry, i can see the info with the UUID but i can not paring or see the list attributes (I have wrote “list attributes” because when I try “list-attributes”, it’s wrote “invalid command”). I have only one line which is : “controller B8:…………..:8F raspberrypi [default]”
So, I just want to know if I can do the same thing with my device =)
Thank you very much !
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Yes, the same shall work with any BLE device which is BLE and using BLE compatible packets.
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Ok, thank you. So, in order to extract “service, descriptor and characteristics informations”, I have to pair before? Because, I tried many times to pair but… without success ! I can only connect.
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Yes, you have to pair first.
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Hi,
Nice article. I was trying to return the battery level from an iPhone, but not having as much luck as you.
I can get all the way to ‘LIST-ATTRIBUTES’ command, but that doesn’t return any results. It doesn’t fail, just doesn’t return anything. Pairing and connection seem ok.
I know this is possible, because my car reports the battery and signal strength of the the iPhone, just wondering if you know any commands to help me get a bit further?
Great blog!
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Hi Nick,
it could be that Apple already does some packet authenification earlier (not sure). Have you tried to inspect the packets with Wireshark (https://mcuoneclipse.com/2016/12/25/tutorial-hexiwear-bluetooth-low-energy-packet-sniffing-with-wireshark/) already?
Erich
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Hi,
Tried this with iPhone, connected and paired ok but no characteristics are returned…
I’m trying to get the battery levels back to my Pi… would you have any ideas what the problem could be?
Thanks.
Nick
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Hi Nick,
I have not tried this with an iPhone. But I know that Apple does things always a bit different. I recommend that you sniff the packets with Wireshark to see what is going on. Have a read at https://mcuoneclipse.com/2016/12/25/tutorial-hexiwear-bluetooth-low-energy-packet-sniffing-with-wireshark/
I hope this helps,
Erich
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Hi, thank you for the post. I am wondering if it is possible to do the same with an Arduino instead of the Pi. I have attempted to pair my Arduino UNO with a HM-10 bluetooth module but never go further than the Hexiwear stating the key… and I have no idea how I can send the key to the Hexiwear to get paired.
Would you have any clues?
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Yes, it should be possible with any device, like the Arduino, if the BLE library on the Arduino supports host mode. I have not used Arduino for this, but this sounds like a bug or missing feature in the Arduino library you are using.
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The BLE module HM-10 that I am using has been configured to host mode, that’s how i managed to get the Hexiwear to pop the 6 digit pin to wait for pairing. Unfortunately my problem starts here because I do not know how to send the pin.
I also attempted to hack the hexiwear so that it doesn’t need a pin to pair but haven’t been successful yet. I will keep trying and see if I may get closer to a solution.
Thank you for writing this blog point – it provided some important insights for me.
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Hello,
I am using partial code which is as follows
# Using Hexiwear with Python
import pexpect
import time
DEVICE = “xx:xx:xx:xx:xx”
print(“Hexiwear address:”),
print(DEVICE)
# Run gatttool interactively.
print(“Run gatttool…”)
child = pexpect.spawn(“gatttool -I”)
# Connect to the device.
print(“Connecting to “),
print(DEVICE),
child.sendline(“connect {0}”.format(DEVICE))
child.expect(“Connection successful”, timeout=5)
print(” Connected!”)
# function to transform hex string like “0a cd” into signed integer
def hexStrToInt(hexstr):
val = int(hexstr[0:2],16) + (int(hexstr[3:5],16)<<8)
if ((val&0x8000)==0x8000): # treat signed 16bits
val = -((val^0xffff)+1)
return val
while True:
child.sendline("char-read-uuid 0x2001")
child.expect("Characteristic value/descriptor: ", timeout=10)
child.expect("\r\n", timeout=10)
print("Accel: "),
print(child.before),
print(float(hexStrToInt(child.before[0:5]))/100),
print(float(hexStrToInt(child.before[6:11]))/100),
print(float(hexStrToInt(child.before[12:17]))/100)
———————————————————————————
I want to get single data only
I am running on
Full version of jessie
python 2.7.9
I am getting following error
——————————————————————————
Hexiwear address: xx:xx:xx:xx:xx:xx
Run gatttool…
Connecting to xx:xx:xx:xx:xx:xx Connected!
Traceback (most recent call last):
File "/home/pi/Desktop/python_gatttool.py", line 30, in
child.expect(“Characteristic value/descriptor: “, timeout=10)
File “/usr/local/lib/python2.7/dist-packages/pexpect/spawnbase.py”, line 341, in expect
timeout, searchwindowsize, async_)
File “/usr/local/lib/python2.7/dist-packages/pexpect/spawnbase.py”, line 369, in expect_list
return exp.expect_loop(timeout)
File “/usr/local/lib/python2.7/dist-packages/pexpect/expect.py”, line 119, in expect_loop
return self.timeout(e)
File “/usr/local/lib/python2.7/dist-packages/pexpect/expect.py”, line 82, in timeout
raise TIMEOUT(msg)
TIMEOUT: Timeout exceeded.
command: /usr/bin/gatttool
args: [‘/usr/bin/gatttool’, ‘-I’]
buffer (last 100 chars): ‘ID failed: Attribute requires authentication before read/write\r\n\x1b[0;94m[xx:xx:xx:xx:xx:xx]\x1b[0m[LE]> ‘
before (last 100 chars): ‘ID failed: Attribute requires authentication before read/write\r\n\x1b[0;94m[xx:xx:xx:xx:xx:xx]\x1b[0m[LE]> ‘
after:
match: None
match_index: None
exitstatus: None
flag_eof: False
pid: 6431
child_fd: 7
closed: False
timeout: 30
delimiter:
logfile: None
logfile_read: None
logfile_send: None
maxread: 2000
ignorecase: False
searchwindowsize: None
delaybeforesend: 0.05
delayafterclose: 0.1
delayafterterminate: 0.1
searcher: searcher_re:
0: re.compile(‘Characteristic value/descriptor: ‘)
—————————————————————————-
I dono how to solve this one.
Thank you
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according to the messages, you have not properly authenticated with the device.
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Thank you for the quick response.
I am following all steps you have mentioned. In addition to that, I am getting similar results which you have mentioned except the error part.
If it is possible for you to provide any reference or procedure to solve this error, it will be helpful to understand your work.
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I have not seen such an error message on my side. Did you enter the pin code as requested on the Hexiwear?
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Yes
I did.
I am able to get data on a terminal but when I run python script it shows this error!
First I tried in the lite version of OS then full version but I am getting the same error.
Should I try on another OS?
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I’m not sure what you mean as ‘lite version of the OS’. You mean a linux distribution without GUI? I don’t believe that this makes any difference. The error message indicates that it is a problem with authentification. I suggest you sniff the packets (see https://mcuoneclipse.com/2016/12/25/tutorial-hexiwear-bluetooth-low-energy-packet-sniffing-with-wireshark/) so you see what is going on or going wrong.
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Hello, thanks a lot for the Blog.
I have some follow up questions: I use a HC-08 BLE Modul and i have some problems. My biggest one is, that i can’t pare the HC-08 with the raspi. After the pairing is never sucsesfull, but it can allways connect to the modul. If i connect to the modul it works but if i pare it cancels the connections after about 15s.
I would like to use Serial Monitores but I only found monitors which need the BLE to be paired. (like minicom)
I quess you had the same error, because youre info looks the same as mine.
Mine:
[HC-08]# info F8:33:31:A4:30:5E
Device F8:33:31:A4:30:5E (public)
Name: HC-08
Alias: HC-08
Paired: no
Trusted: yes
Blocked: no
Connected: yes
LegacyPairing: no
UUID: Generic Access Profile (00001800-0000-1000-8000-00805f9b34fb)
UUID: Generic Attribute Profile (00001801-0000-1000-8000-00805f9b34fb)
UUID: Device Information (0000180a-0000-1000-8000-00805f9b34fb)
UUID: Unknown (0000ffe0-0000-1000-8000-00805f9b34fb)
UUID: Unknown (0000fff0-0000-1000-8000-00805f9b34fb)
Modalias: bluetooth:v000Dp0000d0110
ManufacturerData Key: 0x4348
ManufacturerData Value:
2d 30 38 00 00 00 00 00 00 00 00 00 00 00 00 00 -08………….
00 00 00 00 ….
RSSI: -59
TxPower: 4
[HC-08]#
yourse:
[HEXIWEAR]# info 00:32:40:08:00:12
Device 00:32:40:08:00:12
Name: HEXIWEAR
Alias: HEXIWEAR
Appearance: 0x0380
Paired: yes
Trusted: yes
Blocked: no
Connected: yes
LegacyPairing: no
UUID: Generic Access Profile (00001800-0000-1000-8000-00805f9b34fb)
UUID: Generic Attribute Profile (00001801-0000-1000-8000-00805f9b34fb)
UUID: Device Information (0000180a-0000-1000-8000-00805f9b34fb)
UUID: Battery Service (0000180f-0000-1000-8000-00805f9b34fb)
UUID: Unknown (00002000-0000-1000-8000-00805f9b34fb)
UUID: Unknown (00002010-0000-1000-8000-00805f9b34fb)
UUID: Unknown (00002020-0000-1000-8000-00805f9b34fb)
UUID: Unknown (00002030-0000-1000-8000-00805f9b34fb)
UUID: Unknown (00002040-0000-1000-8000-00805f9b34fb)
UUID: Vendor specific (01ff5550-ba5e-f4ee-5ca1-eb1e5e4b1ce0)
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No, I do not have such a problem. I used the Hexiwear BLE (NXP device) and I don’t have a HC-08 to try. I feel it is a problem of the HC-08 and that it behaves differently?
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Hmm, thanks for the fast answer. I will have to dig a bit deeper. I can reallay relate to your quote “As always, things seem to be rather simple at the start, and the feeling is that ‘someone else must already have done this’. And as many other times, such an assumption turns out to be wrong”
I was so naive to think i can implement it in a view houers. Now I am allready past the view hours XD
Ps: Are you a teacher at the FH Luzern?
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>>Ps: Are you a teacher at the FH Luzern?
yes, see https://mcuoneclipse.com/about/
why are you asking? 😉
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Because i was tempted to write in german, but on second thought it is better to write in english for other members.
And to be honest i am kind of glad that an other competent person was struggeling for a bit with that problem. (I finished my bachelor 6 month ago and started to ask my self how hard it could be to implement a “simple” communication protocol.)
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Thanks again for your Post and have a nice evening. It helped me a lot.
Maby we will bump in to each other one day. (I work at the BFH)
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Indeed! I have not been much at BFH, but with increased MSE lectures this might change over the next semesters.
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Hi Samuel,
well, communication is usually not the easiest thing (I teach that with ‘Advanced Distributed Systems’ too 😉 ). And I’m sure everyone else appreciates using English, because that way it can reaches a larger audience.
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