7477 datasheet(25/48 Pages) RENESAS

25 / 48 page

MITSUBISHI MICROCOMPUTERS

7477/ 7478 GROUP

SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER

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.

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 reg-

ister (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.

Fig. 15 Block diagram of interrupt input and key on wake up circuit

P33/CNTR1

P32/CNTR0

P30/INT0

P31/INT1

P07

P01

EG3

Port P33 data read circuit

CNTR interrupt request signal

Port P32 data read circuit

EG0

Port P30 data read circuit

INT0 interrupt request signal

Port P31 data read circuit

INT1 interrupt request signal

CPU halt state signal

Port P0 data read circuit

EG1

EG5

P00

Pull-up control

Direction register

Pull-up control

Direction register

Pull-up control

Direction register

EG2

Noise

eliminating

circuit

1/2

XCIN

(P50)

XIN

CM7

(

Select gate: At reset, shaded side is connected.).

Note: The 7477 group does not have X CIN input.

EG4

Noise

eliminating

circuit

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