PIC16C711-04/SP Microchip Technology, PIC16C711-04/SP Datasheet - Page 64

• Manufacturer Part Number: PIC16C711-04/SP
• Description: 8-Bit CMOS Microcontrollers with A/D Converter
• Manufacturer: Microchip Technology

PIC16C71X
8.6
During an interrupt, only the return PC value is saved
on the stack. Typically, users may wish to save key reg-
isters during an interrupt i.e., W register and STATUS
register. This will have to be implemented in software.
Example 8-1 stores and restores the STATUS and W
registers. The user register, STATUS_TEMP, must be
defined in bank 0.
The example:
a)
b)
c)
d)
e)
EXAMPLE 8-1:
DS30272A-page 64
Stores the W register.
Stores the STATUS register in bank 0.
Executes the ISR code.
Restores the STATUS register (and bank select
bit).
Restores the W register.
MOVWF
SWAPF
MOVWF
:
:(ISR)
:
SWAPF
MOVWF
SWAPF
SWAPF
Context Saving During Interrupts
W_TEMP
STATUS,W
STATUS_TEMP
STATUS_TEMP,W
STATUS
W_TEMP,F
W_TEMP,W
SAVING STATUS AND W REGISTERS IN RAM
;Copy W to TEMP register, could be bank one or zero
;Swap status to be saved into W
;Save status to bank zero STATUS_TEMP register
;Swap STATUS_TEMP register into W
;Move W into STATUS register
;Swap W_TEMP
;Swap W_TEMP into W
;(sets bank to original state)
1997 Microchip Technology Inc.