Renesas 4514 - Manual (Page 110)

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
SW9 SW11 SW10 SW12
SW16 SW15 SW14 SW13
D
0
D
1
D
2
D
3
P0
0
P0
1
P0
2
P0
3
SW1
SW5
M34513/M34514