Another update from today.
By adding an oscilloscope mode I noticed that PD2 is connected to potentiometer (as a pull-up Vcc). It was necessary to have an independent from the potentiometers button. Now PD3 (INT1) is used to go through different display modes.
In the oscilloscope mode you can amend TimeScale with the left potentiometer.
Download AVR 4 Studio / WinAVR files from here
A video come later.