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4513/4514 Group User’s Manual
APPLICATION
2-7
2.1 I/O pins
2.1.3 Port application examples
(1) Key input by key scan
Key matrix can be set up by connecting keys externally because port D output structure is an N-
channel open-drain and port P0 has the pull-up resistor.
Outline: The connecting required external part is just keys.
Specifications: Port D is used to output “L” level and port P0 is used to input 16 keys. Multiple key
inputs are not detected.
Figure 2.1.1 shows the key input and Figure 2.1.2 shows the key input timing.
Fig. 2.1.1 Key input by key scan
SW4 SW3 SW2
SW8 SW7 SW6
SW9SW11 SW10SW12
SW16 SW15 SW14 SW13
D0
D1
D2
D3
P00
P01
P02
P03
SW1
SW5
M34513/M34514