C51: Updating the Program Counter on the Stack

Information in this article applies to:

• C51 Version 5.50 and later

SYMPTOMS

My project needs to update the program counter during an ISR to "return" to a different function than it interrupted. How can I know the location of a function to implement this in C?

CAUSE

The 8051 does not have an accessible register for the program counter or instruction pointer.

RESOLUTION

Use a pointer to any function you'll be "calling" in this manner. Using indirection, you can receive the address of the function, regardless of where it ultimately ends up being located by the linker.

MORE INFORMATION

• Refer to Application Note 129.

Last Reviewed: Thursday, February 25, 2021