mc68hc908qf4 Freescale Semiconductor, Inc, mc68hc908qf4 Datasheet - Page 129

• Manufacturer Part Number: mc68hc908qf4
• Description: M68hc08 Microcontrollers Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

14.6.1.2 SWI Instruction
MC68HC908QF4 — Rev. 1.0
MOTOROLA
NOTE:
NOTE:
If more than one interrupt is pending at the end of an instruction execution, the
highest priority interrupt is serviced first.
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 return-from-interrupt
(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.
The SWI instruction is a non-maskable instruction that causes an interrupt
regardless of the state of the interrupt mask (I bit) in the condition code register.
A software interrupt pushes PC onto the stack. A software interrupt does not push
PC – 1, as a hardware interrupt does.
Freescale Semiconductor, Inc.
For More Information On This Product,
INT1
INT2
System Integration Module (SIM)
Figure 14-11
Go to: www.freescale.com
CLI
LDA
PSHH
PULH
RTI
PSHH
PULH
RTI
#$FF
.
Interrupt Recognition Example
Figure 14-11
INT1 INTERRUPT SERVICE ROUTINE
INT2 INTERRUPT SERVICE ROUTINE
System Integration Module (SIM)
demonstrates what happens
BACKGROUND ROUTINE
Exception Control
Data Sheet
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