9-12 MC68VZ328 User’s Manual
Programming Model
9.6.4 Interrupt Status Register

During the interrupt service, the interrupt handler determines the source of interrupts by examining the

interrupt status register (ISR). When the bits in this register are set, they indicate that the corresponding

interrupt is posted to the core. If there are multiple interrupt sources at the same level, the software handler

may need to prioritize them, depending on the application.

Each interrupt status bit in this register reflec ts the interrupt request from its respective interrupt source.

When programmed as edge-triggered interrupts, external interrupts INT[3:0], IRQ1, IRQ2, IRQ3, and

IRQ6 can be cleared by writing a 1 to the corresponding status bit in the register. When programmed as

level-triggered interrupts, these interrupts ar e cleared at the requesting sources. All interrupts from internal

peripheral devices are level-triggered interrupts to the interrupt handler, and they are cleared at the

requesting sources.

ISR Interrupt Status Register 0xFFFFF30C

BIT
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 BIT
16
EMI
QRTI SPI
1IRQ
51R
Q6 IRQ
3IRQ
2IRQ
1
TYPE rw rw rw rw rw rw rw rw
RESET0000000000000000
0x00000000
BIT
15 1413121110987654321
BIT
0
PW
M2
UA
RT
2
INT
3INT
2INT
1INT
0PW
M1 KB TM
R2 RT
CWD
T
UA
RT
1
TM
R1 SPI
2
TYPE rw rw rw rw rw rw rw rw rw rw rw rw rw rw
RESET 0000000000000000
0x00000000
Table 9-6. Interrupt Status Register Description
Name Description Settings
Reserved
Bits 31–24 Reserved These bits are reserved
and should be set to 0.
EMIQ
Bit 23 Emulator Interrupt Status—When set, this bit indicates that the
in-circuit emulation module or EMUIRQ pin is requesting an interrupt
on level 7. This bit can be generated from three interrupt sources:
two breakpoint interrupts from the in-circuit emulation module and an
external interrupt from EMUIRQ, which is an active low, edge-sensi-
tive interrupt. To clear this interrupt, you must read the ICEMSR reg-
ister to identify the interrupt source and write a 1 to the
corresponding bit of that register. See Section16.2.4, “In-Circuit
Emulation Module Status Register,” on page16-10 for more infor-
mation.
0 = No emulator interrupt is
pending.
1 = An emulator interrupt is
pending.