PIC16F616 Microchip Technology Inc., PIC16F616 Datasheet - Page 120

• Manufacturer Part Number: PIC16F616
• Description: 14-pin Flash-based, 8-bit Cmos Microcontrollers
• Manufacturer: Microchip Technology Inc.

PIC16F610/616/16HV610/616
12.5
During an interrupt, only the return PC value is saved
on the stack. Typically, users may wish to save key
registers during an interrupt (e.g., W and STATUS
registers). This must be implemented in software.
Temporary
STATUS_TEMP should be placed in the last 16 bytes
of GPR (see Figure 2-4). These 16 locations are
common to all banks and do not require banking. This
makes context save and restore operations simpler.
The code shown in Example 12-1 can be used to:
• Store the W register
• Store the STATUS register
• Execute the ISR code
• Restore the Status (and Bank Select Bit register)
• Restore the W register
EXAMPLE 12-1:
DS41288C-page 118
Note:
MOVWF
SWAPF
MOVWF
:
:(ISR)
:
SWAPF
MOVWF
SWAPF
SWAPF
Context Saving During Interrupts
The PIC16F610/616/16HV610/616 does
not require saving the PCLATH. However,
if computed GOTO’s are used in both the
ISR and the main code, the PCLATH must
be saved and restored in the ISR.
holding
W_TEMP
STATUS,W
STATUS_TEMP
STATUS_TEMP,W
STATUS
W_TEMP,F
W_TEMP,W
SAVING STATUS AND W REGISTERS IN RAM
registers
;Copy W to TEMP register
;Swap status to be saved into W
;Swaps are used because they do not affect the status bits
;Save status to bank zero STATUS_TEMP register
;Insert user code here
;Swap STATUS_TEMP register into W
;(sets bank to original state)
;Move W into STATUS register
;Swap W_TEMP
;Swap W_TEMP into W
W_TEMP
and
Preliminary
© 2007 Microchip Technology Inc.