MC68HC908KX2 MOTOROLA [Motorola, Inc], MC68HC908KX2 Datasheet - Page 88

• Manufacturer Part Number: MC68HC908KX2
• Description: Microcontrollers
• Manufacturer: MOTOROLA [Motorola, Inc]

System Integration Module (SIM)
6.6.1 Interrupts
Technical Data
88
INTERRUPT
INTERRUPT
MODULE
I BIT
I BIT
R/
R/
IAB
IDB
IAB
IDB
MODULE
DUMMY
DUMMY
SP – 4
At the beginning of an interrupt, the CPU saves the CPU register
contents on the stack and sets the interrupt mask (I bit) to prevent
additional interrupts. At the end of an interrupt, the return-from-interrupt
(RTI) instruction recovers the CPU register contents from the stack so
that normal processing can resume.
timing.
Interrupts are latched, and arbitration is performed in the SIM at the start
of interrupt processing. The arbitration result is a constant that the CPU
uses to determine which vector to fetch. As shown in
an interrupt is latched by the SIM, no other interrupt can take
precedence, regardless of priority, until the latched interrupt is serviced
or the I bit is cleared.
SP
PC – 1[7:0] PC – 1[15:8]
CCR
SP – 1
SP – 3
Figure 6-8
Figure 6-8. Interrupt Recovery
Figure 6-7
System Integration Module (SIM)
A
SP – 2
SP – 2
MC68HC908KX8 • MC68HC908KX2 • MC68HC08KX8 — Rev. 1.0
shows interrupt recovery timing.
X
X
.
SP – 3
Interrupt Entry
SP – 1
PC – 1 [7:0] PC – 1 [15:8] OPCODE
A
SP – 4
SP
CCR
Figure 6-7
VECT H
PC
V DATA H
VECT L START ADDR
PC + 1
OPERAND
V DATA L
shows interrupt entry
Figure
OPCODE
MOTOROLA
6-9, once