APD-32A025A Vishay, APD-32A025A Datasheet - Page 4

• Manufacturer Part Number: APD-32A025A
• Description: Intelligent Plasma Display
• Manufacturer: Vishay

APD-32A025A
Vishay Dale
KEYBOARD INTERFACING
The APD-32A025A provides timing signals to scan keyboards of up to 64 keys, using the lockout scan method. Each key is
sequentially scanned and tested for closure. After detection of the first closed key, and after the debounce time (16 msec max)
the address of the key is loaded into the APD-32A025A internal keyboard register (D0-D5). The keyboard register flag bit (D7)
is also set, (high) and the keyboard interrupt request flag (KB IRQ) goes low. The CPU can therefore detect a key closure by
either continuously testing D7 (instruction GKA) or by the CPU interrupt (KB IRQ connected to the CPU interrupt line).
The keyboard flag (D7) will remain high and the keyboard interrupt (KB IRQ) will remain low until the master CPU reads the
keyboard (command GKA). When GKA has been executed the closed keys address will be in the APD-32A025A output
register, D7 will go low and KB IRQ will go high.
The APD-32A025A will scan a keyboard in one of two ways, the 16 key mode or the 64 key mode, which is programmable by
command LKS (load keyboard status). Bounce time is 16 msec max and closure time is 48 msec min. Maximum rate is 10
depressions per second.
www.vishay.com
16
K03
K02
K01
K00
K13
K12
K11
K10
K03
K02
K01
K00
K13
K12
K11
K10
16 KEY X-Y KEYBOARD CONNECTION
12
8
4
0
13
9
5
1
14
10
6
2
D
C
B
A
32
16
48
0
0
15
11
3
7
17
1
1
2
K00
K01
K02
K03
3
4
5
1 OF 16 DECODER
64-KEY KEYBOARD
6
7
10ms
220us
8
9
10
11
12
13
14
Document Number: 37081
14
63
47
31
15
15
Revision 24-May-05