Stack Operation Of Interrupt Processing - Fujitsu F2MC-16LX Hardware Manual

16-bit microcontroller mb90330 series

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CHAPTER 3 INTERRUPT

Stack Operation of Interrupt Processing

Once an interrupt is accepted, the contents of the dedicated registers are automatically

saved in the system stack before control branches to the interrupt handling. Return

from the stack at the end of the interrupt handling also takes place automatically.

Stack Operation at the Start of Interrupt Processing

Once the interrupt is accepted, the CPU automatically saves the contents of the current dedicated registers

and their related data in the system stack in the order below:

1. Accumulator (A)

2. Direct page register (DPR)

3. Additional data bank register (ADB)

4. Data bank register (DTB)

5. Program bank register (PCB)

6. Program counter (PC)

7. Processor status (PS)

Figure 3.10-1 shows the stack operation at the start of interrupt handling.

Previously interrupt

Stack Operation when Interrupt Processing Returns

When the interrupt return instruction (RETI) is executed at the end of interrupt process, the values of PS,

PC, PCB, DTB, ADB, DPR, and A return from the stack in the reverse order for the start of interrupt

handling. The dedicated registers are restored to the initial state preceding the start of interrupt.

Figure 3.10-1 Stack Operation at Start of Interrupt Processing

Immediately interrupt