MODULE CONFIGURATION
AND TEST
RESET STATUS
HALT MONITOR
BUS MONITOR
RESET REQUEST
BERR
SPURIOUS INTERRUPT MONITOR
4
CLOCK
SOFTWARE WATCHDOG TIMER
RESET REQUEST
9
2
PRESCALER
IRQ [7:1]
PERIODIC INTERRUPT TIMER
SYS PROTECT BLOCK
Figure 4-2 System Configuration and Protection
4.2.1 Module Mapping
Control registers for all the modules in the microcontroller are mapped into a 4-Kbyte
block. The state of the module mapping bit (MM) in the SIM module configuration reg-
ister (SIMCR) determines where the control register block is located in the system
memory map. When MM = 0, register addresses range from $7FF000 to $7FFFFF;
when MM = 1, register addresses range from $FFF000 to $FFFFFF.
4.2.2 Interrupt Arbitration
Each module that can generate interrupt requests has an interrupt arbitration (IARB)
field. Arbitration between interrupt requests of the same priority is performed by serial
contention between IARB field bit values. Contention must take place whenever an in-
terrupt request is acknowledged, even when there is only a single request pending.
For an interrupt to be serviced, the appropriate IARB field must have a non-zero value.
If an interrupt request from a module with an IARB field value of %0000 is recognized,
the CPU32 processes a spurious interrupt exception.
MC68331
SYSTEM INTEGRATION MODULE
MOTOROLA
4-3
USER’S MANUAL
MOTOROLA [ MOTOROLA ]
