How to detect RAM memory and variable overlap problems?
You can simply run avr-nm on your output (ELF) file. Run it with the -n option, and it will sort the symbols numerically (by default, they are sorted alphabetically). Look for the symbol _end, that’s the first address in RAM that is not allocated by a variable. (avr-gcc internally adds 0x800000 to all data/bss variable addresses, so please ignore this offset.) Then, the run-time initialization code initializes the stack pointer (by default) to point to the last avaialable address in (internal) SRAM. Thus, the region between _end and the end of SRAM is what is available for stack. (If your application uses malloc(), which e. g. also can happen inside printf(), the heap for dynamic memory is also located there. See Memory Areas and Using malloc().) The amount of stack required for your application cannot be determined that easily. For example, if you recursively call a function and forget to break that recursion, the amount of stack required is infinite. 🙂 You can look at the generated
