Where to find the stack info used in keil c?

i am not sure if the stack is overflow in my project.
thank a lot!

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  • Even if you don't notice problems you always should have an idea about stack usage, it is the only way to rely on your program.

    The used stack is a dynamic characteristic so you only get this information at execution time.

    I will assume large memory model...

    The first step is determine the maximum available stack, you can get this value from map file, look for STACK keyword, for example:
    IDATA 0030H 0001H UNIT STACK
    The space between 30H and the end of internal memory (128 or 256 bytes)will be your available stack.

    1/ Firts option is manual calculation: determine the function call tree and add 2 bytes per call (5 bytes if you use interbank function call). In addition add the stack usage of ISR (more calls and push/pop instructions)

    2/Other option is directly read the SP value at the deepest points of your call function tree. You can estimate the risks.

    3/ A third option, that a friend touch, me is very interesting. You have to initialise the IDATA with a known value "0x55". Later, at any point of ccall function tree, you can scan the idata and determine where the 0x55 appears and so the unused stack. This method even determine the stack usage of ISR (typically more complicate)

    This last method is still more powerfull...

    If you get a crash or a reset (perhaps you have a watchdog) and in systems where there is no RAM initialisation you can at start up take the "photo" of the crash and determine the stack usage.

    I hope all this useful for you.
    Thanks

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