4513_03 Datasheet, PDF (110/210 Pages) Renesas Technology Corp – 4-BIT SINGLE-CHIP MICROCOMPUTER

APPLICATION
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.
M34513/M34514
D0
D1
D2
D3
P00
P01
P02
P03
SW4
SW8
SW12
SW16
SW3
SW7
SW11
SW15
SW2
SW6
SW10
SW14
SW1
SW5
SW9
SW13
Fig. 2.1.1 Key input by key scan
4513/4514 Group User’s Manual
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