Interfacing PIC Microcontrollers

called, this destination address is copied into the program counter, and the

program continues from the new address. At the same time, the return ad-

dress (the one following the CALL) is pushed onto the stack, which is a

block of memory dedicated to this purpose. In the PIC, there are 8 stack ad-

dress storage levels, which are used in turn. The return addresses may thus

be viewed as a stack of items, which must be added and removed in the same

sequence.

The subroutine is terminated with a RETURN instruction, which causes the

program to go back to the original position and continue. This is achieved by

pulling the address from the top of the stack ...