M38C21F3DXXXFP データシートの表示（PDF） - MITSUBISHI ELECTRIC
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M38C21F3DXXXFP Datasheet PDF : 63 Pages
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MITSUBISHI MICROCOMPUTERS
38C2 Group
SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER
Key Input Interrupt (Key-on Wake-Up)
A key input interrupt request is generated by detecting the falling
edge from any pin of ports P00–P03, P54–P57 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 17, where an interrupt request is generated by press-
ing one of the keys consisted as an active-low key matrix which in-
puts to ports P54–P57.
Port PXx
“L” level output
P03 output
P02 output
P01 output
P00 output
P57 input
Segment output
disable register 1
Bit 3 = “1”
Port P03
direction register = “1”
Key input control
register = “1”
✽
✽ ✽ Port P03
latch
Segment output Port P02
disable register 1 direction register = “1”
Bit 2 = “1”
Key input control
✽
✽ ✽ Port P02 register = “1”
latch
Segment output Port P01
disable register 1 direction register = “1”
Bit 1 = “1”
Key input control
✽
✽ ✽ Port P01 register = “1”
latch
Segment output Port P00
disable register 1 direction register = “1”
Bit 0 = “1”
Key input control
✽
✽ ✽ Port P00 register = “1”
latch
Port P57
direction register = “0”
Key input control
✽
✽ ✽ Port P57
register = “1”
latch
✽
P56 input
Port P56
direction register = “0”
✽ ✽ Port P56
latch
Key input control
register = “1”
✽
P55 input
✽
P54 input
Port P55
direction register = “0”
✽✽
Port P55
latch
Key input control
register = “1”
Port P54
direction register = “0”
✽✽
Port P54
latch
Key input control
register = “1”
PULL register
Bit 5 = “1”
Key input interrupt request
Port P0
Input reading circuit
Port P5
Input reading circuit
✽ P-channel transistor for pull-up
✽ ✽ CMOS output buffer
Fig. 17 Connection example when using key input interrupt and ports P0 and P5 block diagram
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