Yes. And basically there are two control units. Beside I have read that they are not communicating between each other, so knock control is used for different stuff than ignition.

In the CPU. RTFM of the CPU.
There is a lot of stuff what helps you.
Including Assembler guide, register layout etc.
Then you "only" have to find which pin from cpu is which "output" (ignition or what ever) OR to understand the code via the knowledge of the maps.
I have still found the VAG-COM routines, but need more time to indentify everything.
In the moment I do the work twice.
A friend has the FR of the RS2 and he gives me small hints when I have detailed questions.
This way also other guys run and I favor this!
Understanding, learning and with some small help you will be able to tune the ECM.