Cannot connect to BLE device on Raspberry Pi

Question

I'm trying to connect to a BLE device (Heart rate sensor, Polar H7), on a Raspberry Pi 2. I use the last version of bluez (5.35) found here: http://www.bluez.org/download/ But when I'm trying to connect using gatttool, I always have "connection refused" error.

Here is what I do :

pi@raspberrypi ~ $ sudo su
root@raspberrypi:/home/pi# hciconfig dev
hci0:   Type: BR/EDR  Bus: USB
        BD Address: 5C:F3:70:69:54:3D  ACL MTU: 1021:8 SCO MTU: 64:1
        DOWN
        RX bytes:616 acl:0 sco:0 events:34 errors:0
        TX bytes:380 acl:0 sco:0 commands:34 errors:0

root@raspberrypi:/home/pi# hciconfig dev up
root@raspberrypi:/home/pi# hcitool lescan
LE Scan ...
00:22:D0:6D:E0:E6 (unknown)
00:22:D0:6D:E0:E6 Polar H7 6DE0E61C
^Croot@raspberrypi:/home/pi# hcitool lecc 00:22:D0:6D:E0:E6
Connection handle 64
root@raspberrypi:/home/pi# gatttool -b 00:22:D0:6D:E0:E6 -I
[00:22:D0:6D:E0:E6][LE]> connect
Attempting to connect to 00:22:D0:6D:E0:E6
Error connect: Connection refused (111)
[00:22:D0:6D:E0:E6][LE]>

I tried to follow this topic: BLE gatttool cannot connect even though device is discoverable with hcitool lescan but it did not work for me.

If you have Bluez, why not just use bluetoothctl? – Zimano Oct 27 '15 at 15:17 — Zimano, Oct 27 '15 at 15:17

Pedro Lobito · Answer 1 · 2020-05-22T10:59:10.610

I was able to connect via Bluetooth from Raspberry to my Android device using gatttool after setting the LE address type to random with the -t random argument, i.e. :

sudo gatttool -t random -b DD:9D:0B:43:A1:77 -I
connect

From gatttool man

--t, ---addr-type=[public | random] 
# Set LE address type. Default: public

USAGE gatttool [OPTION...]

 Help Options:
     -h, --help                                  Show help options
     -h, --help                                  Show help options
     --help-all                                  Show all help options
     --help-gatt                                 Show all GATT commands
     --help-params                               Show  all  Primary  Services/Characteristics
   arguments
     --help-char-read-write                       Show  all  Characteristics Value/Descriptor
   Read/Write arguments

   Application Options:
     --i, ---adapter=hciX                        Specify local adapter interface
     --b, ---device=MAC                          Specify remote Bluetooth address
     --t, ---addr-type=[public | random]         Set LE address type. Default: public
     --m, ---mtu=MTU                             Specify the MTU size
     --p, ---psm=PSM                             Specify the PSM for GATT/ATT over BR/EDR
     --l, ---sec-level=[low | medium | high]     Set security level. Default: low
     --I, ---interactive                         Use interactive mode

What if someone did all of the things in this post? Turning on BLE, using -t random and the connection is still refused? Asking for a friend. — Panossa, Jun 21 '22 at 08:44

score 5 · Answer 2 · edited Nov 25 '16 at 14:37

5

By default GATT is not enable. Add the below lines to /etc/bluetooth/main.conf

EnableLE = true           // Enable Low Energy support. Default is false.
AttributeServer = true    // Enable the GATT attribute server. Default is false.

edited Nov 25 '16 at 14:37

Robert

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answered Nov 25 '16 at 14:19

Hoang Lam

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score 2 · Answer 3 · edited May 29 '21 at 04:22

2

I got it running with:

btmgmt le on

edited May 29 '21 at 04:22

Jeremy Caney

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answered May 28 '21 at 20:42

Klaus

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Sagar Thapa · Answer 4 · 2019-09-25T22:54:49.340

1

Fixed the connection refused (111) issue in my raspberry pi 3B running raspbian buster by Updating/installing BlueZ via apt-get

> sudo apt-get install --no-install-recommends bluetooth

and re running

> sudo gatttool -t random -b E9:1C:89:B7:16:F9 -I

edited Sep 25 '19 at 22:54

answered Sep 25 '19 at 22:46

Sagar Thapa

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score 0 · Accepted Answer · edited Sep 21 '16 at 02:12

0

I had to disable the plugin pnat in /etc/bluetooth/main.conf -> DisablePlugins=pnat. I read that it's unstable, but I don't know much about this plugin.

edited Sep 21 '16 at 02:12

Christian Ternus

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answered Nov 04 '15 at 16:48

Teepeemm

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Good grief, this is the most underrated answer ever! This solved every problem I had on a Raspbian system, after days of other attempts. – Andrea Lazzarotto Jul 20 '22 at 23:16

score 0 · Answer 6 · edited Mar 19 '18 at 00:18

0

If you are still wondering why the random worked. I have gone through the code and this what I found.

-t (Addr:Type: Set LE Address Type)     
Public | random    
Default: Public
A random or static address is a 48-bit randomly generated address and shall meet the following requirements:

• The two most significant bits of the static address shall be equal to ‘1’

• All bits of the random part of the static address shall not be equal to ‘1’

• All bits of the random part of the static address shall not be equal to ‘0’

(Source)

edited Mar 19 '18 at 00:18

Stephen Rauch

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answered Mar 18 '18 at 23:57

ArmCoder

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A link as comment on my answer would be more appropriate than creating a new answer. – Pedro Lobito Sep 11 '18 at 11:05

score -1 · Answer 7 · edited Feb 14 '19 at 15:46

-1

You could try to use gatttool -b 00:22:D0:6D:E0:E6 -I and then connect, just after discovering the MAC without connecting before with hcitool lecc 00:22:D0:6D:E0:E6

edited Feb 14 '19 at 15:46

ascripter

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answered Oct 11 '16 at 17:09

keebOo

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Cannot connect to BLE device on Raspberry Pi

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