mc68hc908kx8 Freescale Semiconductor, Inc, mc68hc908kx8 Datasheet - Page 145

• Manufacturer Part Number: mc68hc908kx8
• Description: M68hc08 Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

is pending upon exit from the original interrupt service routine, the pending interrupt is serviced before the
load-accumulator- from-memory (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.
13.5.1.2 SWI Instruction
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.
13.5.2 Reset
All reset sources always have higher priority than interrupts and cannot be arbitrated.
13.6 Low-Power Modes
Executing the WAIT or STOP instruction puts the MCU in a low power- consumption mode for standby
situations. The SIM holds the CPU in a non-clocked state. Both STOP and WAIT clear the interrupt mask
(I) in the condition code register, allowing interrupts to occur. Low-power modes are exited via an interrupt
or reset.
Freescale Semiconductor
To maintain compatibility with the M68HC05, M6805, and M146805
Families 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.
A software interrupt pushes PC onto the stack. A software interrupt does
not push PC – 1, as a hardware interrupt does.
MC68HC908KX8 • MC68HC908KX2 • MC68HC08KX8 Data Sheet, Rev. 2.1
INT1
INT2
Figure 13-10
CLI
LDA
PSHH
PULH
RTI
PSHH
PULH
RTI
#$FF
.
Interrupt Recognition Example
NOTE
NOTE
INT1 INTERRUPT SERVICE ROUTINE
INT2 INTERRUPT SERVICE ROUTINE
BACKGROUND
ROUTINE
Low-Power Modes
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