![](http://datasheet.mmic.net.cn/30000/MC908QT2CDW_datasheet_2372239/MC908QT2CDW_112.png)
System Integration Module (SIM)
MC68HC908QY/QT Family Data Sheet, Rev. 5
112
Freescale Semiconductor
Figure 13-10
. Interrupt Recognition Example
13.6.1.2 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.
NOTE
A software interrupt pushes PC onto the stack. A software interrupt does
not push PC – 1, as a hardware interrupt does.
13.6.2 Interrupt Status Registers
The flags in the interrupt status registers identify maskable interrupt sources.
Table 13-3 summarizes the
interrupt sources and the interrupt status register flags that they set. The interrupt status registers can be
useful for debugging.
Table 13-3. Interrupt Sources
Priority
Source
Flag
Mask(1)
1. The I bit in the condition code register is a global mask for all interrupt sources except the SWI
instruction.
INT
Register
Flag
Vector
Address
Highest
Lowest
Reset
—
$FFFE–$FFFF
SWI instruction
—
$FFFC–$FFFD
IRQ pin
IRQF
IMASK
IF1
$FFFA–$FFFB
Timer channel 0 interrupt
CH0F
CH0IE
IF3
$FFF6–$FFF7
Timer channel 1 interrupt
CH1F
CH1IE
IF4
$FFF4–$FFF5
Timer overflow interrupt
TOF
TOIE
IF5
$FFF2–$FFF3
Keyboard interrupt
KEYF
IMASKK
IF14
$FFE0–$FFE1
ADC conversion complete interrupt
COCO
AIEN
IF15
$FFDE–$FFDF
CLI
LDA
INT1
PULH
RTI
INT2
BACKGROUND ROUTINE
#$FF
PSHH
INT1 INTERRUPT SERVICE ROUTINE
PULH
RTI
PSHH
INT2 INTERRUPT SERVICE ROUTINE