NJU6010

Ver.2009-08-20

- 4 -

Preliminary

(2-2) Method of Checking the key

The method of checking the key judges the key pressed by fetching the key scanning output signal

(S0~S3) with terminal K0~K5 (Refer to Fig. 2). S0~S3 are fixed at "L" level usually. K0~K5 are input

terminals in the state of the pull-up.

When the key between S1 and K0 is pressed as an example, the K0 is changed from "H" to "L" (Refer

to Fig. 3). NJU6010 detects the pressed key by the change in this K0 signal. And which key was pressed

is checked, the key-scan signal is output from S0~S3 (Refer to Fig. 4).

The scan signal of S1 is input to the terminal K0 by this scan operation (Dot-line in Fig. 3). As a result,

NJU6010 is checked as the key was pressed between S1 and K0.

Fig. 3 Key-scan Checking (Example 1)

Fig. 4 Key-scan Checking (Example 2)

S3

S0

S1

S2

K4 K3

K0

K1

K2

K5

NJU6010

KEY

ON

OFF

SW

0

0

1

1

2

2

3

3

Key input

S0

S1

S2

S3

DATA

Key data fixed

KEY

CSb

K0

1

1

K1~K5

(Pull-up)

Key-scan

Key checking