Previous Program Counter

MPLAB^® X IDE has a Previous Program Counter (PrevPC) display. Its value can be used as follows.

The caller of a subroutine or branch can be identified from the PrevPC value if a breakpoint is set on the first instruction of the destination routine (or subroutine). When the part is halted in the debug session, the PrevPC display in MPLAB X IDE will indicate the address of the calling or branch instruction.

Similarly, if a breakpoint is set on the instruction that follows a BTFSC-pair (not the skipped instruction, but the next one), PrevPC will identify whether or not the skip occurred.

Additionally, if an execution out-of-bounds halt exception occurs, the PrevPC feature can be used to identify the wild-branch instruction that caused the execution out-of-bounds halt exception.