7470 Datasheet, PDF (23/47 Pages) Renesas Technology Corp – SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER

MITSUBISHI MICROCOMPUTERS
7470/7471 Group
SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER
KEY ON WAKE UP
“Key on wake up” is one way of returning from a power down state
caused by the STP or WIT instruction. If any terminal of port P0
has “L” level applied, after bit 5 of the edge polarity selection regis-
ter (EG5) is set to “1”, an interrupt is generated and the
microcomputer is returned to the normal operating state. A key
matrix can be connected to port P0 and the microcomputer can be
returned to a normal state by pushing any key.
The key on wake up interrupt is common with the INT1 interrupt.
When EG5 is set to “1”, the key on wake up function is selected.
However, key on wake up cannot be used in the normal operating
state. When the microcomputer is in the normal operating state,
both key on wake up and INT1 are invalid.
P33/CNTR1
P32/CNTR0
EG3
EG2
EG4
XCIN
(P50)
XIN
P30/INT0
1/2
1/2
CM7
P31/INT1
Noise
eliminating
EG0 circuit
Noise
eliminating
EG1 circuit
CPU halt state signal
Pull-up control
register
P07
Direction register
Port P33 data read circuit
CNTR interrupt request signal
Port P32 data read circuit
Port P30 data read circuit
INT0 interrupt request signal
Port P31 data read circuit
EG5
INT1 interrupt request signal
Pull-up control
register
P01
Direction register
Port P0 data read circuit
Pull-up control
register
P00
Direction register
(
Select gate: At reset, shaded side is connected.)
Note : The 7470 group does not have XCIN input.
Fig. 13 Block diagram of interrupt input and key on wake up circuit
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