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Under
development
Preliminary Specifications REV.D
Specifications in this manual are tentative and subject to change.
Mitsubishi Microcomputers
M16C/80 group
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
Interrupts
64
Interrupt Enable Flag (I Flag)
The interrupt enable flag (I flag) is used to disable/enable maskable interrupts. When this flag is set
(= 1), all maskable interrupts are enabled; when the flag is cleared to 0, they are disabled. This flag
is automatically cleared to 0 after a reset is cleared.
Interrupt Request Bit
This bit is set (= 1) by hardware when an interrupt request is generated. The bit is cleared to 0 by
hardware when the interrupt request is acknowledged and jump to the interrupt vector.
This bit can be cleared to 0 (but cannot be set to 1) in software.
Interrupt Priority Level Select Bit and Processor Interrupt Priority Level (IPL)
Interrupt priority levels are set by the interrupt priority select bit in an interrupt control register. When
an interrupt request is generated, the interrupt priority level of this interrupt is compared with the
processor interrupt priority level (IPL). This interrupt is enabled only when its interrupt priority level is
greater than the processor interrupt priority level (IPL). This means that you can disable any particu-
lar interrupt by setting its interrupt priority level to 0.
Figure 1.9.4. Exit priority register
Exit priority register
Symbol
Address
When reset
RLVL
009F16
XXXX00002
Bit
name
Function
Bit symbol
b7
b6
b5
b4
b3
b2
b1
b0
0 0 0 : Level 0
0 0 1 : Level 1
0 1 0 : Level 2
0 1 1 : Level 3
1 0 0 : Level 4
1 0 1 : Level 5
1 1 0 : Level 6
1 1 1 : Level 7
b2 b1 b0
FSIT
RLVL1
RLVL2
RLVL0
Interrupt priority set bit for
exiting Stop/Wait state
(Note 1,2)
Note 1: Exits the Stop or Wait mode when the requested interrupt priority level is
higher than that set in the exit priority register.
Note 2: Set to the same value as the processor interrupt priority level (IPL) set in
the flag register (FLG).
Note 3: The high-speed interrupt can only be specified for interrupts with
interrupt priority level 7. Specify interrupt priority level 7 for only one
interrupt.
W
R
Nothing is assigned.
When write, set "0". When read, their contents are indeterminate.
0: Interrupt priority level 7 = normal
interrupt
1: Interrupt priority level 7 = high-speed
interrupt
High-speed interrupt
set bit (Note 3)