ra8816 RAIO Technology Inc., ra8816 Datasheet - Page 40

• Manufacturer Part Number: ra8816
• Description: 144x65 Character/graphic Lcd Driver
• Manufacturer: RAIO Technology Inc.

Preliminary Version 1.6
RAiO TECHNOLOGY INC.
6-6 Key-Scan
6-7 I/O Port
The RA8816 built-in 4x5 key-scan circuit for extra key board function to help user integrate a key
matrix application. In auto-mode, MPU can read the key code from register to know the key was short-
press, long-presee or key released. User can also adjust the cycle time of key-scan. Figure 6-30 is the
simple application curcuit. Table 6-4 is the mapping keyboard code of key matrix as Figure 6-30. So
MPU knows which key be pressed by reading register – KSDR.
In Auto-Mode of Key-Scan function, if the key pressed over one second, then the RA8816 will cause
interrupt and change the data of register – KSDR to a long-press code. Therefore MPU knows which
key was pressed ove one second.
The RA8816 provide eight general purpose I/O pins. Each I/O pin is easy to setup as input or output.
They can use to drive LED, wakeup the RA8816 or provide information for whole system.
KIN0
KIN1
KIN2
KIN3
KIN4
Table 6-4: Keyboard Code(BCD Code) of Auto-Mode
RA8815
KST3 KST2 KST1 KST0 KST3 KST2 KST1 KST0
Figure 6-30: 4x5 Key Matrix Curcuit
15
16
17
18
19
Short-Press
KST3
KST2
KST1
KST0
KIN4
KIN3
KIN2
KIN1
KIN0
10
11
12
13
14
05
06
07
08
09
40/68
00
01
02
03
04
35
36
37
38
39
Long-Press
30
31
32
33
34
144x65 Character/Graphic LCD Driver
25
26
27
28
29
20
21
22
23
24
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RA8816