41
CHAPTER 3 CPU
3.4.5
Stack Operation at Interrupt Processing
This section describes how values in registers are saved and restored at interrupt
processing.
■
Stack Operation at the Beginning of Interrupt Processing
After accepting an interrupt, the CPU automatically saves the values in the program counter (PC) and
program status (PS) in the stack.
Figure 3.4-5 shows the stack operation at the beginning of interrupt processing.
Figure 3.4-5 Stack Operation at the Beginning of Interrupt Processing
■
Stack Operation at the End of Interrupt Processing
When the return instruction (RETI) is executed at the end of interrupt processing, the values in the program
status (PS) and the program counter (PC) are restored from the stack in that order (which is opposite to that
at the beginning of interrupt processing). This operation restores the values in the PS and PC to those
values used before interruption.
Note:
Values in the accumulator (A) and temporary accumulator (T) are not automatically saved in the stack.
Therefore, save and restore the values using the PUSHW and POPW instructions.
027C
H
XX
H
027D
H
XX
H
027E
H
XX
H
027F
H
XX
H
0280
H
XX
H
0281
H
XX
H
027C
H
08
H
027D
H
70
H
027E
H
E0
H
027F
H
00
H
0280
H
XX
H
0281
H
XX
H
E000
H
PC
0870
H
PS
0280
H
SP
E000
H
PC
0870
H
PS
027C
H
SP
PS
PC
Immediately before
interruption
Address
Memory
Address
Memory
Immediately after
interruption
Содержание F2MC-8L F202RA
Страница 2: ......
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Страница 32: ...16 CHAPTER 1 OVERVIEW ...
Страница 90: ...74 CHAPTER 3 CPU ...
Страница 142: ...126 CHAPTER 5 TIME BASE TIMER POPW A RETI ENDS END ...
Страница 150: ...134 CHAPTER 6 WATCHDOG TIMER ...
Страница 174: ...158 CHAPTER 7 8 BIT PWM TIMER User processing POPW A XCHW A T Restoring A and T POPW A RETI ENDS ...
Страница 176: ...160 CHAPTER 7 8 BIT PWM TIMER ...
Страница 220: ...204 CHAPTER 8 8 16 BIT CAPTURE TIMER COUNTER ...
Страница 240: ...224 CHAPTER 9 12 BIT PPG TIMER ...
Страница 258: ...242 CHAPTER 10 EXTERNAL INTERRUPT CIRCUIT 1 EDGE PUSHW A User processing POPW A XCHW A T POPW A RETI ENDS END ...
Страница 274: ...258 CHAPTER 11 EXTERNAL INTERRUPT CIRCUIT 2 LEVEL ...
Страница 362: ...346 CHAPTER 15 BUZZER OUTPUT ...
Страница 371: ...355 CHAPTER 16 WILD REGISTER FUNCTION 16 3 5 Data Test Set Register WROR A test register Do not access this register ...
Страница 390: ...374 CHAPTER 17 FLASH MEMORY ...
Страница 419: ...403 INDEX INDEX The index follows on the next page This is listed in alphabetic order ...
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