
Interrupts
65
Specifications in this manual are tentative and subject to change
Rev. E
MITSUBISHI MICROCOMPUTERS
M30245 Group
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
Address-Match Interrupt
An address-match interrupt is generated when the address-match interrupt address register contents
match the program counter value. Two address-match interrupts can be set, each of which can be enabled
and disabled by an address-match interrupt enable bit. The interrupt enable flag (I flag) does not affect
address-match interrupts and processor interrupt priority level (IPL).
Figure 1.40 shows the address-match interrupt-related registers.
Figure 1.40. Address-match interrupt-related register Interrupt precautions
Bit name
Bit symbol
Symbol
Address
When reset
AIER
000916
XXXXXX002
Address match interrupt enable register
Function
W
R
Address match interrupt 0
enable bit
0 : Interrupt disabled
1 : Interrupt enabled
AIER0
Address match interrupt 1
enable bit
AIER1
Symbol
Address
When reset
RMAD0
001216 to 001016
X0000016
RMAD1
001616 to 001416
X0000016
Nothing is assigned.
b7
b6
b5
b4
b3
b2
b1
b0
W
R
Address setting register for address match interrupt
Function
Values that can be set
Address match interrupt register i (i = 0, 1)
0000016 to FFFFF16
Nothing is assigned.
0 : Interrupt disabled
1 : Interrupt enabled
b0 b7
b0
b3
(b19)
(b16)
b7
b0
(b15)
(b8)
b7
(b23)
Write 0 when writing to these bits. If read, the value is indeterminate.
Precautions
Reading address 0000016
When maskable interrupt occurs, the CPU reads the interrupt information (the interrupt number and
interrupt request level) in the interrupt sequence. The interrupt request bit of the interrupt written in
address 0000016 will then be set to “0”.
Do not read address 0000016 by software. Reading address 0000016 by software sets enabled highest
priority interrupt source request bit to “0”. Though the interrupt is generated, the interrupt routine may not
be executed.
Setting the stack pointer
The value of the stack pointer immediately after reset is initialized to 000016. Accepting an interrupt
before setting a value in the stack pointer may cause program runaway. Be sure to set a value in the
stack pointer before accepting an interrupt.
When using the NMI interrupt, initialize the stack pointer at the beginning of a program. Generating any
interrupts including the NMI interrupt is prohibited for the first instruction immediately after reset.