38K0 Datasheet, PDF (18/133 Pages) Mitsubishi Electric Semiconductor – SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER

38K0 Group
Key Input Interrupt (Key-on Wake Up)
A Key-on wake up interrupt request is generated by applying a
falling edge to any pin of port P0 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 interrupt request is generated by pressing
one of the keys consisted as an active-low key matrix which inputs
to ports P00–P03.
Port PXx
“L” level output
P07 output
P06 output
P05 output
P04 output
P03 input
P02 input
P01 input
P00 input
PULL 0 register
Port P07
Bit 7 = “0”
direction register = “1”
✽
✽ ✽ _{Port P07}
latch
PULL 0 register
Bit 6 = “0”
Port P06
direction register = “1”
✽
✽ ✽ _{Port P06}
latch
PULL 0 register
Bit 5 = “0”
Port P05
direction register = “1”
✽
✽ ✽ _{Port P05}
latch
PULL 0 register
Bit 4 = “0”
Port P04
direction register = “1”
✽
✽ ✽ _{Port P04}
latch
PULL 0 register
Bit 3 = “1”
Port P03
direction register = “0”
✽
✽ ✽ _{Port P03}
latch
PULL 0 register
Bit 2 = “1”
Port P02
direction register = “0”
✽
✽ ✽ _{Port P02}
latch
PULL 0 register
Bit 1 = “1”
Port P01
direction register = “0”
✽
✽ ✽ _{Port P01}
latch
PULL 0 register
Bit 0 = “1”
Port P00
direction register = “0”
✽
✽ ✽ _{Port P00}
latch
Key input interrupt request
Port P0
Input reading circuit
✽ P-channel transistor for pull-up
✽ ✽ CMOS output buffer
Fig. 15 Connection example when using key input interrupt and port P0 block diagram
Rev.3.00 Oct 05, 2006 page 18 of 129
REJ03B0192-0300