Day: June 27, 2016

Getting started with Bluetooth Low Energy on Linux

I’m working with BLE on Linux and decided to share here my finding.

First you will need a Bluetooth Low Energy (BLE) compatible host, then if your laptop’s bluetooth is not BLE compatible you will need a bluetooth dongle.

Searching in the Internet I discovered that this low cost CSR V4.0 is compatible.

When plugin it on my laptop I got this info:

[ 8972.648662] usb 3-3: new full-speed USB device number 16 using xhci_hcd
[ 8972.870695] usb 3-3: New USB device found, idVendor=0a12, idProduct=0001
[ 8972.870699] usb 3-3: New USB device strings: Mfr=0, Product=2, SerialNumber=0
[ 8972.870702] usb 3-3: Product: CSR8510 A10

Let see the lsusb listing (idVendor=0a12, idProduct=0001):

# lsusb 
Bus 003 Device 016: ID 0a12:0001 Cambridge Silicon Radio, Ltd Bluetooth Dongle (HCI mode)

Ok, but for some strange reason my Debian 8.0 delayed some time (~30s) to get it working, strange but at least:

# hciconfig -a hci0
hci0: Type: BR/EDR Bus: USB
BD Address: 00:1A:7D:DA:XX:XX ACL MTU: 310:10 SCO MTU: 64:8
RX bytes:10241 acl:0 sco:0 events:348 errors:0
TX bytes:1738 acl:0 sco:0 commands:47 errors:0
Features: 0xff 0xff 0x8f 0xfe 0xdb 0xff 0x5b 0x87
Packet type: DM1 DM3 DM5 DH1 DH3 DH5 HV1 HV2 HV3
Name: 'inspire'
Class: 0x00010c
Service Classes: Unspecified
Device Class: Computer, Laptop
HCI Version: 4.0 (0x6) Revision: 0x22bb
LMP Version: 4.0 (0x6) Subversion: 0x22bb
Manufacturer: Cambridge Silicon Radio (10)

Now let search for a Bluetooth LE device:

# hcitool lescan
LE Scan ...
BC:6A:29:AB:3F:46 (unknown)
BC:6A:29:AB:3F:46 SensorTag
BC:6A:29:AB:3F:46 (unknown)
BC:6A:29:AB:3F:46 SensorTag
BC:6A:29:AB:3F:46 (unknown)

You can connect to this device using the gattool

# gatttool -I
[                 ][LE]> help
help                                           Show this help
exit                                           Exit interactive mode
quit                                           Exit interactive mode
connect         [address [address type]]       Connect to a remote device
disconnect                                     Disconnect from a remote device
primary         [UUID]                         Primary Service Discovery
included        [start hnd [end hnd]]          Find Included Services
characteristics [start hnd [end hnd [UUID]]]   Characteristics Discovery
char-desc       [start hnd] [end hnd]          Characteristics Descriptor Discovery
char-read-hnd                          Characteristics Value/Descriptor Read by handle
char-read-uuid   [start hnd] [end hnd]   Characteristics Value/Descriptor Read by UUID
char-write-req              Characteristic Value Write (Write Request)
char-write-cmd              Characteristic Value Write (No response)
sec-level       [low | medium | high]          Set security level. Default: low
mtu                                     Exchange MTU for GATT/ATT
[                 ][LE]> connect BC:6A:29:AB:3F:46
Attempting to connect to BC:6A:29:AB:3F:46
Connection successful

// Let to list primary Services:
[BC:6A:29:AB:3F:46][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: 0x0022 uuid: 0000180a-0000-1000-8000-00805f9b34fb
attr handle: 0x0023, end grp handle: 0x002a uuid: f000aa00-0451-4000-b000-000000000000
attr handle: 0x002b, end grp handle: 0x0035 uuid: f000aa10-0451-4000-b000-000000000000
attr handle: 0x0036, end grp handle: 0x003d uuid: f000aa20-0451-4000-b000-000000000000
attr handle: 0x003e, end grp handle: 0x0048 uuid: f000aa30-0451-4000-b000-000000000000
attr handle: 0x0049, end grp handle: 0x0054 uuid: f000aa40-0451-4000-b000-000000000000
attr handle: 0x0055, end grp handle: 0x005c uuid: f000aa50-0451-4000-b000-000000000000
attr handle: 0x005d, end grp handle: 0x0061 uuid: 0000ffe0-0000-1000-8000-00805f9b34fb
attr handle: 0x0062, end grp handle: 0x0068 uuid: f000aa60-0451-4000-b000-000000000000
attr handle: 0x0069, end grp handle: 0xffff uuid: f000ffc0-0451-4000-b000-000000000000

//Let see the visible characteristics:
[BC:6A:29:AB:3F:46][LE]> char-desc 0x0018 0x002A
handle: 0x0018, uuid: 00002a26-0000-1000-8000-00805f9b34fb
handle: 0x0019, uuid: 00002803-0000-1000-8000-00805f9b34fb
handle: 0x001a, uuid: 00002a27-0000-1000-8000-00805f9b34fb
handle: 0x001b, uuid: 00002803-0000-1000-8000-00805f9b34fb
handle: 0x001c, uuid: 00002a28-0000-1000-8000-00805f9b34fb
handle: 0x001d, uuid: 00002803-0000-1000-8000-00805f9b34fb
handle: 0x001e, uuid: 00002a29-0000-1000-8000-00805f9b34fb
handle: 0x001f, uuid: 00002803-0000-1000-8000-00805f9b34fb
handle: 0x0020, uuid: 00002a2a-0000-1000-8000-00805f9b34fb
handle: 0x0021, uuid: 00002803-0000-1000-8000-00805f9b34fb
handle: 0x0022, uuid: 00002a50-0000-1000-8000-00805f9b34fb
handle: 0x0023, uuid: 00002800-0000-1000-8000-00805f9b34fb
handle: 0x0024, uuid: 00002803-0000-1000-8000-00805f9b34fb
handle: 0x0025, uuid: f000aa01-0451-4000-b000-000000000000
handle: 0x0026, uuid: 00002902-0000-1000-8000-00805f9b34fb
handle: 0x0027, uuid: 00002901-0000-1000-8000-00805f9b34fb
handle: 0x0028, uuid: 00002803-0000-1000-8000-00805f9b34fb
handle: 0x0029, uuid: f000aa02-0451-4000-b000-000000000000
handle: 0x002a, uuid: 00002901-0000-1000-8000-00805f9b34fb

Nice! Everthing is working!

The “gatttool” is deprecated and will be removed soon, then we need to use bluetoothctl instead! This way:

# bluetoothctl
//scan for BLE devices:
[bluetooth]# scan on
Discovery started
[CHG] Controller 00:1A:7D:DA:71:10 Discovering: yes
[CHG] Device EC:F2:E5:CE:30:5B RSSI: -44
[CHG] Device EC:F2:E5:CE:30:5B RSSI: -52
[CHG] Device EC:F2:E5:CE:30:5B RSSI: -44

//connect to it:
[bluetooth]# connect EC:F2:E5:CE:30:5B
Attempting to connect to EC:F2:E5:CE:30:5B
[CHG] Device EC:F2:E5:CE:30:5B Connected: yes
Connection successful

//get information from device
[Nordic_UART]# info
Device EC:F2:E5:CE:30:5B
	Name: Nordic_UART
	Alias: Nordic_UART
	Paired: no
	Trusted: yes
	Blocked: no
	Connected: yes
	LegacyPairing: no
	UUID:                           (1800)
	UUID:                           (1801)
	UUID: Vendor specific           (6e400001-b5a3-f393-e0a9-e50e24dcca9e)
	RSSI: -44

//list the attributes
[Nordic_UART]# list-attributes
Service /org/bluez/hci0/dev_EC_F2_E5_CE_30_5B/service0009 Vendor specific (Primary)
Characteristic /org/bluez/hci0/dev_EC_F2_E5_CE_30_5B/service0009/char000d Vendor specific
Characteristic /org/bluez/hci0/dev_EC_F2_E5_CE_30_5B/service0009/char000a Vendor specific
Descriptor /org/bluez/hci0/dev_EC_F2_E5_CE_30_5B/service0009/char000a/desc000c Client Characteristic Configuration

//get information from an attribute:
[Nordic_UART]# attribute-info /org/bluez/hci0/dev_EC_F2_E5_CE_30_5B/service0009
Service - Vendor specific
	UUID: 6e400001-b5a3-f393-e0a9-e50e24dcca9e
	Primary: yes
	Characteristics: /org/bluez/hci0/dev_EC_F2_E5_CE_30_5B/service0009/char000a
	Characteristics: /org/bluez/hci0/dev_EC_F2_E5_CE_30_5B/service0009/char000d

The listing of primary services you can find here:

The listing of characteristics you can find here:

Case you don’t have a BLE compatible device to search for, you can transform your smartphone in a BLE device using the peripheral mode application: