7641 datasheet(23/138 Pages) RENESAS

23 / 138 page

7641 Group

Rev.4.00

Aug 28, 2006

page 23 of 135

REJ03B0191-0400

Key Input Interrupt (Key-on Wake-Up)

A key input interrupt request is generated by applying “L” level to any

pin of port P2 that have been set to input mode. In other words, it is

generated when AND of input level goes from “1” to “0”. An example

of using a key input interrupt is shown in Figure 18, where an inter-

rupt request is generated by pressing one of the keys consisted as

an active-low key matrix which inputs to ports P20–P24.

Fig. 18 Connection example when using key input interrupt and port P2 block diagram

✻✻✻

Port P27

latch

Port P27

direction register = “1”

P27 output

Port P2 pull-up control register

Bit 7 = “0”

Port PXx

“L” level output

Key input interrupt request

Falling edge

detector

P26 output

P25 output

P24 input

P23 input

P22 input

P21 input

P20 input

✻✻✻

Port P26

latch

Port P26

direction register = “1”

Port P2 pull-up control register

Bit 6 = “0”

Falling edge

detector

✻✻✻

Port P25

latch

Port P25

direction register = “1”

Port P2 pull-up control register

Bit 5 = “0”

Falling edge

detector

✻✻✻

Port P24

latch

Port P24

direction register = “0”

Port P2 pull-up control register

Bit 4 = “0”

Falling edge

detector

✻✻✻

Port P23

latch

Port P23

direction register = “0”

Port P2 pull-up control register

Bit 3 = “0”

Falling edge

detector

✻✻✻

Port P22

latch

Port P22

direction register = “0”

Port P2 pull-up control register

Bit 2 = “0”

Falling edge

detector

✻✻✻

Port P21

latch

Port P21

direction register = “0”

Port P2 pull-up control register

Bit 1 = “0”

Falling edge

detector

✻✻✻

Port P20

latch

Port P2 pull-up control register

Bit 0 = “0”

Falling edge

detector

Port P20

direction register = “0”

Port P2

Input reading circuit

✻ P-channel transistor for pull-up

✻✻ CMOS output buffer

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