M37544G Mitsubishi Electric, M37544G Datasheet - Page 17

• Manufacturer Part Number: M37544G
• Description: Single-Chip 8-Bit CMOS Microcomputer
• Manufacturer: Mitsubishi Electric

Interrupts
Interrupts occur by 12 different sources : 5 external sources, 6 in-
ternal sources and 1 software source.
Interrupt control
All interrupts except the BRK instruction interrupt have an interrupt
request bit and an interrupt enable bit, and they are controlled by
the interrupt disable flag. When the interrupt enable bit and the in-
terrupt request bit are set to “1” and the interrupt disable flag is set
to “0”, an interrupt is accepted.
The interrupt request bit can be cleared by program but not be set.
The interrupt enable bit can be set and cleared by program.
The reset and BRK instruction interrupt can never be disabled with
any flag or bit. All interrupts except these are disabled when the
interrupt disable flag is set.
When several interrupts occur at the same time, the interrupts are
received according to priority.
Interrupt operation
Upon acceptance of an interrupt the following operations are auto-
matically performed:
1. The processing being executed is stopped.
2. The contents of the program counter and processor status reg-
3. The interrupt disable flag is set and the corresponding interrupt
4. Concurrently with the push operation, the interrupt destination
Notes 1: Vector addressed contain internal jump destination addresses.
Table 6 Interrupt vector address and priority
Reset (Note 2)
Serial I/O receive
Serial I/O transmit
INT
INT
Key-on wake-up
CNTR
CNTR
Timer X
Reserved area
Reserved area
Timer A
Reserved area
A-D conversion
Timer 1
Reserved area
BRK instruction
Interrupt source
ister are automatically pushed onto the stack.
request bit is cleared.
address is read from the vector table into the program counter.
0
1
2: Reset function in the same way as an interrupt with the highest priority.
0
1
Priority
10
12
13
—
—
—
11
—
1
2
3
4
5
6
7
8
9
Vector addresses (Note 1)
High-order
FFED
FFDD
FFFD
FFFB
FFEF
FFEB
FFE9
FFE7
FFE5
FFE3
FFDF
FFF9
FFF7
FFF5
FFF3
FFF1
FFE1
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
Low-order
FFDC
FFFC
FFEE
FFEC
FFEA
FFDE
FFFA
FFF8
FFF6
FFF4
FFF2
FFF0
FFE8
FFE6
FFE4
FFE2
FFE0
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
At reset input
At completion of serial I/O data receive
At completion of serial I/O transmit shift or
when transmit buffer is empty
At detection of either rising or falling edge of
INT
At detection of either rising or falling edge of
INT
At falling of conjunction of input logical level
for port P0 (at input)
At detection of either rising or falling edge of
CNTR
At detection of either rising or falling edge of
CNTR
At timer X underflow
Not available
Not available
At timer A underflow
Not available
At completion of A-D conversion
At timer 1 underflow
Not available
At BRK instruction execution
Interrupt request generating conditions
0
1
input
input
0
1
input
input
When setting the followings, the interrupt request bit may be set to
“1”.
•When setting external interrupt active edge
Related register: Interrupt edge selection register (address
003A16)
Timer X mode register (address 2B
Timer A mode register (address 1D
When not requiring the interrupt occurrence synchronized with
these setting, take the following sequence.
Notes on use
Set the corresponding interrupt enable bit to “0” (disabled).
Set the interrupt edge select bit (active edge switch bit) to “1”.
Set the corresponding interrupt request bit to “0” after 1 or
more instructions have been executed.
Set the corresponding interrupt enable bit to “1” (enabled).
SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER
MITSUBISHI MICROCOMPUTERS
Non-maskable
External interrupt
(active edge selectable)
External interrupt
(active edge selectable)
External interrupt (valid at falling)
External interrupt
(active edge selectable)
External interrupt
(active edge selectable)
STP release timer underflow
Non-maskable software interrupt
16
16
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7544 Group
Remarks
17