Grumpy_Mike:
In machine code you just need to set the interrupt vector to the address of the ISR function, something I can't see your code doing. But in C it is a bit more complex than this as internal registers need to be saved and restored.
I thought that is done by declaring the function as ISR and the mapping is done via the name.
If not, how do code samples like that
https://playground.arduino.cc/Main/PinChangeInterrupt
work at all?
SO, how do I set the vector then?
Can you name just one please? I am sure it will not be valid.
The most simple one: I want to understand how it's done without having the arduino-framework do it for me.
Just in case I need to do the same thing without the arduinoIDE, let's say using AtmelStudio.