15
MITSUBISHI MICROCOMPUTERS
3806 Group
SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER
INTERRUPTS
Interrupts occur by sixteen sources: seven external, eight internal,
and one software.
Interrupt control
Each interrupt is controlled by an interrupt request bit, an interrupt
enable bit, and the interrupt disable flag except for the software in-
terrupt set by the BRK instruction. An interrupt occurs if the corre-
rupt disable flag is “0”.
Interrupt enable bits can be set or cleared by software.
Interrupt request bits can be cleared by software, but cannot be
set by software.
The BRK instruction cannot be disabled with any flag or bit. The I
(interrupt disable) flag disables all interrupts except the BRK in-
struction interrupt.
Interrupt operation
When an interrupt is received, the contents of the program counter
and processor status register are automatically stored into the
stack. The interrupt disable flag is set to inhibit other interrupts
from interfering.The corresponding interrupt request bit is cleared
and the interrupt jump destination address is read from the vector
table into the program counter.
Notes on use
When the active edge of an external interrupt (INT0 to INT4,
CNTR0, or CNTR1) is changed, the corresponding interrupt re-
quest bit may also be set. Therefore, please take following se-
quence;
(1) Disable the external interrupt which is selected.
(2) Change the active edge selection.
(3) Clear the interrupt request bit which is selected to “0”.
(4) Enable the external interrupt which is selected.
Interrupt Source
Reset (Note 2)
INT0
INT1
Serial I/O1
reception
Serial I/O1
transmission
Timer X
Timer Y
Timer 1
Timer 2
CNTR0
CNTR1
Serial I/O2
INT2
INT3
INT4
A-D converter
BRK instruction
Low
FFFC16
FFFA16
FFF816
FFF616
FFF416
FFF216
FFF016
FFEE16
FFEC16
FFEA16
FFE816
FFE616
FFE416
FFE216
FFE016
FFDE16
FFDC16
High
FFFD16
FFFB16
FFF916
FFF716
FFF516
FFF316
FFF116
FFEF16
FFED16
FFEB16
FFE916
FFE716
FFE516
FFE316
FFE116
FFDF16
FFDD16
Table 1. Interrupt vector addresses and priority
Priority
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
Interrupt Request
Generating Conditions
At reset
At detection of either rising or
falling edge of INT0 input
At detection of either rising or
falling edge of INT1 input
At completion of serial I/O1
data reception
At completion of serial I/O1
transfer shift or when
transmission buffer is empty
At timer X underflow
At timer Y underflow
At timer 1 underflow
At timer 2 underflow
At detection of either rising or
falling edge of CNTR0 input
At detection of either rising or
falling edge of CNTR1 input
At completion of serial I/O2
data transfer
At detection of either rising or
falling edge of INT2 input
At detection of either rising or
falling edge of INT3 input
At detection of either rising or
falling edge of INT4 input
At completion of A-D conversion
At BRK instruction execution
Remarks
Non-maskable
External interrupt
(active edge selectable)
External interrupt
(active edge selectable)
Valid when serial I/O1 is selected
STP release timer underflow
External interrupt
(active edge selectable)
External interrupt
(active edge selectable)
Valid when serial I/O2 is selected
External interrupt
(active edge selectable)
External interrupt
(active edge selectable)
External interrupt
(active edge selectable)
Non-maskable software interrupt
Note 1: Vector addresses contain interrupt jump destination addresses.
2: Reset function in the same way as an interrupt with the highest priority.
Vector Addresses (Note 1)