C51: Creating a Fixed Stack Segment

Information in this article applies to:

• C51 All Versions

QUESTION

Is it possible to define a fixed stack location for the 8051's hardware stack?

ANSWER

Yes. The easiest way to do this is to modify the STARTUP code so the stack is an absolute segment at a fixed location. For example:

In the STARTUP code, change the following:

?STACK          SEGMENT   IDATA
                RSEG    ?STACK
                DS      100h-080h

to:

ISEG    AT      0xA0
?STACK: DS      0x100 - ?STACK

This creates an absolute segment for the stack. Then, you can change the 0xA0 to the address where you want the stack to reside. This has the advantage that if your C program variables overlap with the stack, the linker emits a warning.

SEE ALSO

• C51: Calculating Stack Size
• C51: Checking for Stack Underflow at Runtime
• C51: Locating the Stack after IDATA Variables
• C51: Defining the Minimum Stack Size

Last Reviewed: Thursday, February 25, 2021