I got an embedded Linux BeagleBone Black and would like to do a project that combines C++ and Embedded Linux.
I google'd many times that combination but all the results I found involved external Hardware which I'd like to avoid (only HW I have is a LED and a button, which are enough for me).
Could you please suggest an idea for a project which I could practice C++ and Embedded Linux?
I think you will have a hard time doing interesting 'embedded' programming without any external hardware.
I would recommend going to a place like SparkFun[1] and get a cheap Graphic LCD (you can ask the guys at SparkFun what would be appropriate) and write some code to display data in different ways.
One you are happy with that buy a breakout board with some sort of sensor, maybe an inertial measurement unit (IMU). Write code to read the data from the IMU and display it on the LCD.
Next get a motor driver or two and a couple of motors and learn how to drive them.
Then put everything together; build and program a balance bot.