TC9328AF datasheet(32/84 Pages) TOSHIBA

32 / 84 page

TC9328AF

2004-09-13

Return Processing from Interrupt Processing Routine

In order to make it return to processing before receiving Interrupt from Interrupt processing routine,

RNI instruction which is an exclusive command is used.

Execution of RNI instruction follows the processing automatically one by one.

① The contents of address stack, which is specified with a stack pointer, are returned to a program

counter.

② Set “1” to interrupt master enable and changes into an enable state.

③ The contents of a stack pointer are done

+1.

RNI instruction of the above-mentioned processing is processed in 1 instruction cycle.

Interrupt Processing Routine

Interruption is received regardless of the program currently performed when an interruption request will

be done if it is the program area where interruption is enabled. Therefore, after doing interrupt processing,

when making it return to the program of a basis, it is necessary to return to the state where it is performed

by interrupt processing. For this reason, it is necessary to perform shunting and return operation within an

interruption processing routine about a register, a data memory, etc. which may be operated within an

interruption processing routine at least.

(1)

Shunting processing

In execution of shunting processing, a carry flag surely needs to be shunted. If interruption is

received during execution of arithmetic operation, the contents will change about carry flag (CY) etc.

and the program after a return will mistake judgment. For this reason, the contents of a carry flag

are shunted in a data memory at once by IN1 instruction in the data of the carry flag in I/O map.

The contents of the data memory used by the interruption processing routine and the contents of a

general register are also made to shunt if needed. Furthermore, when MVGD, MVGS or DAL

instruction is used in interrupt routine, it’s necessary to shunt the contents of G-register or DAL

address register.

(2)

Return processing

Return processing should just do opposite to the above-mentioned shunting processing.

If interrupt is received, interrupt master enable flag is reset by “0”, before receiving interrupt, an

interrupt master enable flag must have been “1”.

For this reason, RNI instruction is executed and a master enable flag is returned.

Multiplex Interrupt

Multiplex Interrupt is the method of processing another interrupt during interrupt processing.

As shown in the figure, another interrupt factor C or D is processed during interrupt processing to a

certain interrupt factor A and B. The depth of interrupt at this time is called interrupt level.

Main

routine

MAIN

Interrupt

level 1

Interrupt

level 2

Interrupt

level 3

Interrupt

level 4

The example of multiplex interrupt

TC9328AF Datasheet(PDF) 32 Page - Toshiba Semiconductor

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