M38203M4 Datasheet, PDF (37/344 Pages) Mitsubishi Electric Semiconductor – 8-BIT SINGLE-CHIP MICROCOMPUTER

MITSUBISHI MICROCOMPUTERS
3820 Group
SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER
Key Input Interrupt (Key-on Wake Up)
A Key input interrupt request is generated by applying “L” level to
any pin of port P3 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 9,
where an interrupt request is generated by pressing one of the
keys consisted as an active-low key matrix which inputs to ports
P20–P23.
Port PXx
"L" level output
P27 output
PULL register A
Bit 2 = "1"
Port P27
direction register = "1"
V
V V _{Port P27}
latch
V
P26 output
Port P26
direction register = "1"
V V _{Port P26}
latch
V
P25 output
V
P24 output
Port P25
direction register = "1"
V V _{Port P25}
latch
Port P24
direction register = "1"
V V _{Port P24}
latch
V
P23 input
Port P23
direction register = "0"
V V _{Port P23}
latch
V
P22 input
Port P22
direction register = "0"
V V _{Port P22}
latch
V
P21 input
Port P21
direction register = "0"
V V _{Port P21}
latch
V
P20 input
Port P20
direction register = "0"
V V _{Port P20}
latch
Key input interrupt request
Port P2
Input reading circuit
V P-channel transistor for pull-up
V V CMOS output buffer
Fig. 17 Connection example when using key input interrupt and port P2 block diagram
3820 GROUP USER’S MANUAL
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