Fig. 6.1 General Flow Of Interrupt Operation - Fujitsu MB90420/5 (A) Series Hardware Manual

MB90420/5 (A) SERIES F
n Interrupt
Figure 6.1 shows 4 types of interrupt start and return functions process.
START
Valid hardware
interrupt request?
String family*
instruction
executing
Fetch and decode next
instruction.
INT instruction?
RETI
Instruction?
Execute ordinary
instruction
Repetitive
NO
execution of string family*
instruction completed?
Move pointer to next instruction by
updating PC
*: Interrupt determination is performed by the step during execution of string family instruction
2
MC-16LX FAMILY 16-BIT MICROCONTROLLERS HARDWARE MANUAL
Main program
YES
NO
YES
Save dedicated
NO registers to system
stack
Disable acceptance of hardware
interrupt (I = 0)
YES
NO
Return to dedicated registers
from system stack, call
interrupt routine, and return to
previous routine
YES

Fig. 6.1 General Flow of Interrupt Operation

EI2OS?
Software
interrupt or
exception
handling
Hardware
interrupt
Save dedicated registers to
system stack.
Update CPU interrupt
processing level (ILM).
Return processing
due to interrupt
Read interrupt vector,
update PC and PCB,
and branch to interrupt
routine.
6-4
Interrupt start/return processing
YES
2
EI OS
2
Perform EI OS
NO
handling
YES
Specified count
ended? Or termination
request issued from
resource?
NO