Unable to create dev/rfcomm port

I am have Bluno nano and would like to connect it my pc(Ubuntu 16.06) and receive information via blue tooth. some online Q&A but unable to make it work.

1. I paired Bluno nano my pc (checked via - $ bluetoothctl , [bluetooth]# paired-devices).

2. After that I ran $ sudo rfcomm bind 0 F4:5E:AB:AA:BB:CC 1

but I am unable to see /dev/rfcomm0 . Do I need to create any config files ?

Connection to blutooth is done by the following commands

$ rfkill list all
$ sudo rfkill unblock bluetooth
$ sudo hciconfig hci0 up
$ sudo bluetoothctl
[bluetooth]# power on
[bluetooth]# discoverable on
[bluetooth]# agent on
[bluetooth]# pairable on
[bluetooth]# scan on
[bluetooth]# scan off
[bluetooth]# connect F4:5E:AB:AA:BB:CC
[bluno]# pair F4:5E:AB:AA:BB:CC
[bluno]# trust F4:5E:AB:AA:BB:CC

1

1 Answer

This method worked for me.

After you paired to the device and connected connected successfully, discover services that are using rfcomm on the remote device:

sdptool browse <remote_dev>
sdptool browse 12:34:56:78:11:22

take note of all the possible rfcomm and their channels (remote_channel)

Now create a virtual rfcomm device on our machine:

rfcomm listen /dev/rfcomm0 2

you can replace 2 with any value. it is our channel

Then bind the remote rfcomm to our virtual rfcomm device:

sudo rfcomm bind <virtual_rfcommdev> <remote_mac> <remote_channel>
sudo rfcomm bind /dev/rfcomm0 12:34:56:78:11:22 2

if you prefer a one liner

 rfcomm bind 0 12:34:56:78:11:22 1

You can check if it is worked by sending it a test AT command

first install picocom:

sudo apt install picocom

then check if the device is present:

ls /dev/rfcomm*

then start picocom on the rfcomm:

sudo picocom -c /dev/rfcomm0

-c to make the command visible as you type

you get sometime like

picocom v2.2
port is : /dev/rfcomm0
flowcontrol : none
baudrate is : 9600
parity is : none
databits are : 8
stopbits are : 1
escape is : C-a
local echo is : no
noinit is : no
noreset is : no
nolock is : no
send_cmd is : sz -vv
receive_cmd is : rz -vv -E
imap is :
omap is :
emap is : crcrlf,delbs,
terminal is ready

now type AT and press enter. If you get OK then it working.

9

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