M38C88EA-XXXFP Просмотр технического описания (PDF) - MITSUBISHI ELECTRIC
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M38C88EA-XXXFP Datasheet PDF : 51 Pages
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MITSUBISHI MICROCOMPUTERS
38C8 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 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 15, 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–P23.
Port PXx
“L” level output
P27 output
P26 output
P25 output
P24 output
P23 input
P22 input
P21 input
P20 input
PULL register A
Bit 2 = “1”
Key input control register = “1”
Port P27 direction
register = “1”
✽
✽✽ Port P27
latch
Key input control register = “1”
Port P26 direction
register = “1”
✽
✽✽ Port P26
latch
Key input control register = “1”
Port P25 direction
register = “1”
✽
✽✽ Port P25
latch
Key input control register = “1”
Port P24 direction
register = “1”
✽
✽✽ Port P24
latch
Key input control register = “1”
Port P23 direction
register = “0”
✽
✽✽ Port P23
latch
Key input control register = “1”
Port P22 direction
register = “0”
✽
✽✽ Port P22
latch
Key input control register = “1”
Port P21 direction
register = “0”
✽
✽✽ Port P21
latch
Key input control register = “1”
Port P20 direction
register = “0”
✽
✽✽ Port P20
latch
Key input interrupt request
Port P2
Input reading circuit
✽ P-channel transistor for pull-up
✽✽ CMOS output buffer
Fig. 15 Connection example when using key input interrupt and port P2 block diagram
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