MC68HC908JK3EMP MOTOROLA [Motorola, Inc], MC68HC908JK3EMP Datasheet - Page 90

• Manufacturer Part Number: MC68HC908JK3EMP
• Description: Microcontrollers
• Manufacturer: MOTOROLA [Motorola, Inc]

System Integration Module (SIM)
Technical Data
90
NOTE:
If more than one interrupt is pending at the end of an instruction
execution, the highest priority interrupt is serviced first.
demonstrates what happens when two interrupts are pending. If an
interrupt is pending upon exit from the original interrupt service routine,
the pending interrupt is serviced before the LDA instruction is executed.
The LDA opcode is prefetched by both the INT1 and INT2 RTI
instructions. However, in the case of the INT1 RTI prefetch, this is a
redundant operation.
To maintain compatibility with the M6805 Family, the H register is not
pushed on the stack during interrupt entry. If the interrupt service routine
modifies the H register or uses the indexed addressing mode, software
should save the H register and then restore it prior to exiting the routine.
System Integration Module (SIM)
INT1
INT2
Figure 7-11
CLI
LDA
PSHH
PULH
RTI
PSHH
PULH
RTI
#$FF
.
Interrupt Recognition Example
MC68H(R)C908JL3E/JK3E/JK1E
INT1 INTERRUPT SERVICE ROUTINE
INT2 INTERRUPT SERVICE ROUTINE
Figure 7-11
BACKGROUND ROUTINE
MOTOROLA
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Rev. 2.0