NJU6625 New Japan Radio Co.,Ltd, NJU6625 Datasheet - Page 10

• Manufacturer Part Number: NJU6625
• Description: Nju6625 12character 1-line Dot Matrix Lcd Controller Driver With Smooth Scroll Function
• Manufacturer: New Japan Radio Co.,Ltd

NJU6625
- 10 -
(1-9) Keyscan circuit
SEG
SEG
SEG
SEG
SEG
SEG
SEG
SEG
scans 4x8 key matrix and fetches conditions of 32 keys. Furthermore, it operates correctly against the
key roll over input.
REQ
Example Keyscan
from the “REQ” terminal to notice the key pressing information to an application system.
changed in busy of key data reading operation. Key data is fetched into the key register after 2 clock of
the end of a keyscan cycle and kept by the start of next cycle.
signals are output in interval period of segment signals. Key data input terminals (K
up to V
voltage of V
pressing is not operating and key data input terminals (K
keyscan (t
voltage of V
The Keyscan circuit consists of a detector block of key pressing and a fetching block of key status. It
When the NJU6625 detect the key-in by the key scan circuit, it outputs “H” signal as the request signal
The request signal resets to “L” level before 2 clock of next scanning.
Contents of key register are “0000 0000” in case of no key operation. Contents of key register are not
Keyscan signal output terminals operate as segment terminals (SEG
Keyscan operation is turned ON or OFF by the instruction. In case of keyscan OFF, the detector of key
1
2
3
4
5
6
7
8
/S
/S
/S
/S
/S
/S
/S
/S
Request signal output
Contents of key register renewal
Key data input terminal and segment terminal
Keyscan OFF mode
0
1
2
3
4
5
6
7
DD
KS
in busy of keyscan operation (t
2
2
). In the period of keyscan (t
or V
or V
S
S
S
S
S
S
S
S
0
1
2
3
4
5
6
7
LCD2
LCD2
Prelimina ry
.
.
t
KS
KS
KS
). In this period, terminals of SEG
S
S
S
S
S
S
S
S
), all of segment terminals (SEG
0
1
2
3
4
5
6
7
0
to K
3
) are not pulled up during the period of
1
to SEG
S
S
S
S
S
S
S
S
0
1
2
3
4
5
6
7
1
9
to SEG
8
to SEG
) also and keyscan
0
to K
71
71
3
) output the
) are pulled
output the
Ver.2008-03-21