MITSUBISHI MICROCOMPUTERS
7477/7478 GROUP
SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER
INTERRUPTS
When the device is put into power-down state by the STP instruc-
tion or the WIT instruction, if bit 5 in the edge polarity selection
register is “1”, the INT1 interrupt becomes a key on wake up inter-
rupt. When a key on wake up interrupt is valid, an interrupt request
is generated by applying the “L” level to any pin in port P0. In this
case , the port used for interrupt must have been set for the input
mode.
Interrupts can be caused by 13 different sources consisting of five
external, seven internal, and one software sources.
Interrupts are vectored interrupts with priorities shown in Table 1.
Reset is also included in the table because its operation is similar
to an interrupt.
When an interrupt is accepted, the registers are pushed, interrupt
disable flag I is set, and the program jumps to the address speci-
fied in the vector table. The interrupt request bit is cleared
automatically. The reset and BRK instruction interrupt can never
be disabled. Other interrupts are disabled when the interrupt dis-
able flag is set.
If bit 5 in the edge polarity selection register is “0” when the device
is in power-down state, the INT1 interrupt is selected. Also, if bit 5
in the edge polarity selection register is set to “1” when the device
is not in a power-down state, neither key on wake up interrupt re-
quest nor INT1 interrupt request is generated.
All interrupts except the BRK instruction interrupt have an interrupt
request bit and an interrupt enable bit. The interrupt request bits
are in interrupt request registers 1 and 2 and the interrupt enable
bits are in interrupt control registers 1 and 2. External interrupts
INT0 and INT1 can be asserted on either the falling or rising edge
as set in the edge polarity selection register. When “0” is set to this
register, the interrupt is activated on the falling edge; when “1” is
set to the register, the interrupt is activated on the rising edge.
The CNTR0/CNTR1 interrupts function in the same as INT0 and
INT1. The interrupt input pin can be specified for either CNTR0 or
CNTR1 pin by setting bit 4 in the edge polarity selection register.
Figure 4 shows the structure of the edge polarity selection regis-
ter, interrupt request registers 1 and 2, and interrupt control
registers 1 and 2.
Interrupts other than the BRK instruction interrupt and reset are
accepted when the interrupt enable bit is “1”, interrupt request bit
is “1”, and the interrupt disable flag is “0”. The interrupt request bit
can be reset with a program, but not set. The interrupt enable bit
can be set and reset with a program.
Reset is treated as a non-maskable interrupt with the highest pri-
ority. Figure 5 shows interrupts control.
Table 1. Interrupt vector address and priority.
Interrupt source
Priority
Vector addresses
Remarks
______
RESET
1
2
FFFF16, FFFE16
FFFD16, FFFC16
FFFB16, FFFA16
FFF916, FFF816
FFF716, FFF616
FFF516, FFF416
FFF316, FFF216
FFF116, FFF016
FFEF16, FFEE16
FFED16, FFEC16
FFEB16, FFEA16
FFE916, FFE816
Non-maskable
INT0 interrupt
External interrupt (polarity programmable)
External interrupt (INT1 is polarity programmable)
External interrupt (polarity programmable)
INT1 interrupt or key on wake up interrupt
CNTR0 interrupt or CNTR1 interrupt
Timer 1 interrupt
3
4
5
Timer 2 interrupt
6
Timer 3 interrupt
7
Timer 4 interrupt
8
Serial I/O receive interrupt
Serial I/O transmit interrupt
A-D conversion completion interrupt
BRK instruction interrupt
9
10
11
12
Non-maskable software interrupt
11
MITSUBISHI [ Mitsubishi Group ]
