Note, use 'software serial' mode on Arduino, as regular uart (pins 0, 1) are also used for USB communication (needed by the IDE).
In the example use pins 2, 3 for RX/TX.
Use voltage divider to get 5v output from Arduino to 3.3v safe for RX on HC-05.
On power up, 2 blinks per second = disconnected
Connect using android device, with 'Serial Bluetooth Terminal' app
Pair device, then connect.
Now should have a steady led
Use code from - https://github.com/bugwhine/arduino/blob/master/bluetooth/bluetooth.ino
Default baud rate for bluetooth side is 9600
From arduino IDE, run program, and open serial monitor
Should be possible to communicate between arduino serial monitor and bluetooth serial app on phone
[steve Arduino]$ hcitool scan
[steve Arduino]$ sudo rfcomm bind 0 98:D3:32:20:87:15 1
[steve Arduino]$ sudo minicom -s
Serial Port Setup
A - Serial Device : /dev/rfcomm0
E - Bps/Par/Bits
Serial comms should now work between minicom, and the arduino serial monitor.
sudo dnf install bluez-libs-devel
sudo npm -g install bluetooth-serial-port
Use example code from https://github.com/eelcocramer/node-bluetooth-serial-port,
Received: Size of data buf = 1
Received: Size of data buf = 6