Rev. 1.0, 02/00, page 111 of 1141
6.4
Interrupt Operation
6.4.1
Interrupt Control Modes and Interrupt Operation
Interrupt operations in this LSI differ depending on the interrupt control mode.
NMI* interrupts and address trap interrupts are accepted at all times except in the reset state. In
the case of IRQ interrupts and on-chip supporting module interrupts, an enable bit is provided for
each interrupt. Clearing an enable bit to 0 disables the corresponding interrupt request. Interrupt
sources in which the enable bits are set to 1 are controlled by the interrupt controller.
Table 6.5 shows the interrupt control modes.
The interrupt controller performs interrupt control according to the interrupt control mode set by
the INTM1 and INTM0 bits in SYSCR, the priorities set in ICR, and the masking state indicated
by the I and UI bits in the CPU’s CCR.
Note: * In this LSI, the NMI interrupt is generated by the watchdog timer.
Table 6.5
Interrupt Control Modes
SYSCR
Interrupt
Control
Mode
INTM1
INTM0
Priority Setting
Register
Interrupt
Mask Bits
Description
0
0
ICR
I
Interrupt mask control is
performed by the I bit
Priority can be set with ICR
1
0
1
ICR
I, UI
3-level interrupt mask control is
performed by the I and UI bits
Priority can be set with ICR