Safely getting out of an interrupt

[MOUNTAIN747]

All I'm after is to transfer to a location other than where the INT occurred. I'm going to take a closer look at DT_INTs-14 and try to figure out if there are any system var that need to be dealt with. Other than that I think the only thing that is needed is to pop the stack and loose the address.

[richard]

I think the only thing that is needed is to pop the stack and loose the address

dream on

typical stack implementation from data sheet core14 non enhanced pic

4.3.2 STACK
The PIC16F627A/628A/648A family has an 8-level
deep x 13-bit wide hardware stack (Figure 4-1). The
stack space is not part of either program or data space
and the Stack Pointer is not readable or writable. The
PC is PUSHed onto the stack when a
CALL instruction
is executed or an interrupt causes a branch. The stack
is POPed in the event of a
RETURN, RETLW or a
RETFIE
instruction execution. PCLATH is not affected
by a PUSH or POP operation.





Note
1: There are no Status bits to indicate stack overflow or stack underflow conditions.2:There are no instructions/mnemonics called PUSH or POP. These are actions that occur from the execution of the
CALL, RETURN, RETLW and RETFIE instructions, or the vectoring to an interrupt address.

[Charlie]

A safer approach is to simply have the interrupt set a flag and return. You main program can be a tight loop that checks flags. When to detects the flag, it GOSUBs to the new location.

[mpgmike]

;Interrupt Processor:
ASM
INT_LIST  macro    ; IntSource,  Label,     Type, ResetFlag? 
        INT_Handler   INT_INT,   _OK,       PBP,  yes   ;USART CS
        INT_Handler   AT1_INT,   _Fire,     PBP,  yes   ;Fires Coil
        INT_Handler   IOC_INT,   _Wipe,     PBP,  yes   ;Fires Output
        INT_Handler   RX_INT,    _Grab,     PBP,  yes   ;USART Transmission Received
        INT_Handler   T1G_INT,   _Get_RPM,  PBP,  yes   ;Count Pulses to Determine RPM
        INT_Handler   TMR3_INT,  _Stall,    PBP,  yes   ;RPM Below Limits of TMR1
    endm
    INT_CREATE                      ;Creates the interrupt processor
ENDASM

This is a typical DT_INT Declaration. As you can see, when an external interrupt occurs the program jumps to a Label called "OK". When an Angular Timer Interrupt occurs it jumps to "Fire". Each Interrupt has a different Label the DT_INT INCLUDE will sent the PC to. An IOC INT directs the PC to "Wipe", and so forth. This may be the part you missed based on your comment,

"All I'm after is to transfer to a location other than where the INT occurred."