MC68HC05J3 Datasheet, PDF (55/92 Pages) Motorola, Inc – High-density Complementary Metal Oxide Semiconductor (HCMOS) Microcomputer Unit

Reset
Yes
Is I-bit set?
No
IRQ/keyboard
interrupt?
Yes
Clear IRQ request
latch
No
Core timer
Yes
interrupt?
Stack
PC, X, A, CC
No
Set I-bit
16-bit timer
Yes
7
interrupt?
Load PC from:
IRQ/key: $0FFA-$0FFB
No
Core timer: $0FF8-$0FF9
Timer IC: $1FF6-$1FF7
Fetch next
instruction
Timer OC: $1FF4-$1FF5
Timer OVF: $1FF2-$1FF3
SWI
instruction?
No
RTI
instruction?
No
Execute instruction
Yes
Yes
Restore registers from
stack:
CC, A, X, PC
MC68HC05J3
Figure 7-2 Interrupt flow chart
RESETS AND INTERRUPTS
TPG
MOTOROLA
7-5