The normal process of debugging problems like this is to reduce the code set to the bare minimum that still demonstrates the errors or aberrant behavior. I doubt that anyone here wants to look through all your code.

It is not uncommon that in the process of doing the code reduction you can very often come to realize the problem on your own.

You still have not said anything about which MCU you are using. If anyone is going to be able to offer further help they would certainly want and need to know that.

You have mentioned an oscilloscope but alluded to not using it. This is often an essential tool to gain understanding of what is going on with the MCU code. Setting and clearing various port pins can be used to track the code execution path of your reduced but still not working code.

Programming in C on MCUs does require that you have a good grounding in the MCU architecture and how the assembly language / machine code work. When you compile/link your code with the newer version of the Keil tools I suggest strongly that you study the memory layout of the executable code produced by the tool set to ensure that it is 100% plausible.

Michael Karas