Stack Overflow Summary

1. The stack is not big enough
2.  Is there a statement in the subroutine that directly or conditionally jumps out of the subroutine body? If so, a stack overflow will occur after running the subroutine N times
3. The page is not set properly for program jumps, table lookups, etc.
4. Different uses of GOTO and CALL instructions In the PIC assembly program, the CALL and GOT0 instructions are used in different places. CALL is used to call a subroutine, and after calling the subroutine, it returns to the program before the call; while GOTO is an unconditional transfer, that is, it enters another state from this state without returning. In order to make the program more readable and the process clearer and more reasonable, the program usually adopts modular programming, that is, the program is divided into different subroutines according to function, and the main program is quite simple, and only the CALL instruction is used to call the subroutine. Since the stack of the PIC microcontroller is limited, the GOTO instruction cannot be used endlessly in the program, otherwise it will cause the stack to overflow and the program cannot run normally. But sometimes, such as when the program branches, the GOTO instruction has to be used. For the PICl6F7x series of microcontrollers, when a program branches, it can only be judged by the Z bit or C bit of the STATUS register. At this time, in the first of the two situations, the GOTO instruction must be used to transfer; otherwise, after executing the first situation, the second situation will be executed immediately. The program is as follows: BTFSS STATUS, Z GOTO A GOTO B When jumping to A, the GOTO instruction must be used; otherwise, after executing this statement, GOTO B will be executed immediately. In this way, no matter what the value of Z is, the program will jump to B. For GOT0 B, the GOTO instruction does not need to be used. In the above case, since GOTO only jumps within the subroutine, the internal loop of the small program occupies a small number of stack levels, so it is feasible to use the GOTO instruction. However, when using the GOTO instruction in a large program, it may not be possible to return to the next instruction before the call. Therefore, the author recommends that when using assembly language for programming, the program should be