74
3.5
Interrupt Operation
3.5.1
Interrupt Control Modes and Interrupt Operation
Interrupt operations in the H8S/2678 Series differ depending on the interrupt control mode.
NMI interrupts are accepted at all times except in the reset state and the hardware standby 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 for which the enable bits are set to 1 are controlled by the interrupt controller.
Table 3.6 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 INTCR, the priorities set in IPR, and the masking state indicated by
the I bit in the CPU’s CCR, and bits I2 to I0 in EXR.
Table 3.6
Interrupt Control Modes
Interrupt
INTCR
Priority
Control
Mode
INTM1
INTM0
Setting
Registers
Interrupt
Mask Bits
Description
0
0
0
—
I
Interrupt mask control is performed by
the I bit.
—
1
—
—
Setting prohibited
2
1
0
IPR
I2 to I0
8-level interrupt mask control is
performed by bits I2 to I0.
8 priority levels can be set with IPR.
—
1
—
—
Setting prohibited
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