Topic : Use more that 255 Bytes in stack (STM8208RB)

Forum : ST7/STM8

Original Post
Post Information Post
October 8, 2009 - 9:00am
Guest

Hello,

Thank you for quickly answer last time.

We need tables larger than 256 Bytes.

For that time we create function like that:

void f1(char tab){
char tab2[200];
...
}

void main(void){
char tab1[200];
f1(tab1);
}

But it's very cmplicated when we handle very large table.

Do exist better solution.

Regards,

Coucou
Replies
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October 8, 2009 - 9:41am
Raisonance Support Team

Hi,

The STM8 is not able to handle objects on stack that are more than "255 bytes deep". This is because the "SP+offset" addressing mode uses a 1-byte offset.

So the easiest way to handle your problem is to put your table in RAM, not on the stack. There are 2 way to do this:
1) Specify the array as static in your function. The array will be visible only within your function, and will NOT be initialized upon function entry.
2) Declare the array as global (outside of a function)

3) Another alternative, if you do not want your code to be modified, is to use the Raisonance-specific LARGESTACK option. You can then address objects further than 255 bytes deep on stack, but the generated code is ugly, so this option should be used only as a last resort.

Regards,
Bruno