7702 datasheet(76/217 Pages) RENESAS

76 / 217 page

7702/7703 Group User’s Manual

INTERRUPTS

4–14

4.7 Sequence from acceptance of interrupt request to execution of interrupt routine

The sequence from the acceptance of interrupt request to the execution of the interrupt routine is described

below.

When an interrupt request is accepted, the interrupt request bit which corresponds to the accepted interrupt

is cleared to “0,” and then the interrupt processing starts from the next cycle of completion of the instruction

which is being executed at accepting the interrupt request. Figure 4.7.1 shows the sequence from acceptance

of interrupt request to execution of interrupt routine.

After execution of an instruction at accepting the interrupt request is completed, an INTACK (Interrupt

Acknowledge) sequence is executed, and a branch is made to the start address of the interrupt routine

allocated in addresses 016 to FFFF16.

The INTACK sequence is automatically performed in the following order.

The contents of the program bank register (PG) just before performing the INTACK sequence are stored

to stack.

The contents of the program counter (PC) just before performing the INTACK sequence are stored to

stack.

The contents of the processor status register (PS) just before performing the INTACK sequence is stored

to stack.

The interrupt disable flag (I) is set to “1.”

The interrupt priority level of the accepted interrupt is set into the processor interrupt priority level (IPL).

The contents of the program bank register (PG) are cleared to “0016,” and the contents of the interrupt

vector address are set into the program counter (PC).

Performing the INTACK sequence requires at least 13 cycles of internal clock

φ. Figure 4.7.2 shows the

INTACK sequence timing.

Execution is started beginning with an instruction at the start address of the interrupt routine after completing

the INTACK sequence.

4.7 Sequence from acceptance of interrupt request to execution of interrupt routine

7702 Datasheet(PDF) 76 Page - Renesas Technology Corp