mc68hc908gt8 Freescale Semiconductor, Inc, mc68hc908gt8 Datasheet - Page 141

• Manufacturer Part Number: mc68hc908gt8
• Description: M68hc08 Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

After every instruction, the CPU checks all pending interrupts if the I bit is not set. If more than one
interrupt is pending when an instruction is done, the highest priority interrupt is serviced first. In the
example shown in
pending interrupt is serviced before the LDA instruction is executed.
Freescale Semiconductor
STACKING
Figure
ORDER
MC68HC908GT16 • MC68HC908GT8 • MC68HC08GT16 Data Sheet, Rev. 5.0
13-5, if an interrupt is pending upon exit from the interrupt service routine, the
INT1
INT2
5
4
3
2
1
Figure 13-5
1. High byte of index register is not stacked.
Figure 13-4. Interrupt Stacking Order
PROGRAM COUNTER (HIGH BYTE)
PROGRAM COUNTER (LOW BYTE)
INDEX REGISTER (LOW BYTE)
CONDITION CODE REGISTER
CLI
LDA
PSHH
PULH
RTI
PSHH
PULH
RTI
ACCUMULATOR
#$FF
.
Interrupt Recognition Example
•
•
•
•
•
•
(1)
INT1 INTERRUPT SERVICE ROUTINE
INT2 INTERRUPT SERVICE ROUTINE
$00FF DEFAULT ADDRESS ON RESET
1
2
3
4
5
UNSTACKING
ORDER
BACKGROUND
ROUTINE
Interrupts
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