How to Find Stack Overflow in Microcontrollers using C in Run Time

Question

I am creating the application on STM32 microcontroller. I am using some library stack. Above that stack, I am using my application. I have two questions:

1. How can I detect and handle the stack over flow in runtime. Because I don't know how much memory that library is using.

2. How can I detect and handle the stack over flow in runtime if I am developing the code from the scratch. I read some where we have to maintain some count for each declaration. Is this correct way or any standard way to find it.

Answer 1

if you are limited to your device and no "high sophisticated" tools available, you could at least try "the old way". A simple stack guard may help. Somewhere in your code (depends on the tools you use), there must be the definition of the stack area. Something similar to:

.equ         stacksize, 1024

stack:       .space   stacksize,0

(gnu as syntax, your's might be different)

with your device's startup code somewhere initializing the stack register to the top address of the stack area.

A stack guard would then just add a "magic number" to the stack top and bottom:

.equ         stackmagic,0xaffeaffe
.equ         stacksize, 1024


stacktop:    .int     stackmagic
stack:       .space   stacksize,0
stackbottom: .int     stackmagic

with some code at least periodically checking (e.g. in a timer interrupt routine or - if available - in your debugger) if the stackmagic values are still there.