NJU6538 View Datasheet(PDF) - Japan Radio Corporation

Part Name

Description

Manufacturer

NJU6538

1/8, 1/9, 1/10 Duty BITMAP LCD DRIVER with KEY SCAN

Japan Radio Corporation  

NJU6538

(5-2) Data output timing

The data output format shows bellow. The data output mode is set by “L” status of SCL terminal at the

rising signal of CE terminal.

CE

SCL

SIO

* KD1 KD2

SIO state Output

Key data

Output

KD24 KD25 PSF

Output

(5-3) Power save flag (PSF)

The status of Power save flag is outputted after KD25 in Key data reading. This flag sets “1” signal in

mode of Power save in Key data reading and sets “0” in mode of Normal.

(5-4) Timing of Key scan

Key scan cycle is 160T[S] (T=1/fsys=2/fosc,fsys : Internal system clock frequency). The data of key

scan is a result of comparison with a couple of Key scan for correct judge whether Key On or Off. When

the result of comparison is correct (accord), the NJU6538 recognizes Key On and outputs “L” level from

SIO terminal after 322T[S] from start of Key scan for a request to read key data out to external MPU.

When the SIO terminals outputs “L” signal, the key scan does not operate until end of key data reading

by MPU, and scanned key data is kept. When the result of comparison is incorrect (not accord), Key

scan operates again if any key is On. Therefore, Key scan may operate incorrectly in case of shorter

period of Key on than 322T[S]

Key ON

160T[s]

S0

*1 1

1

*1

S1 *1

2

2

*1

S2 *1

3

3

*1

S3 *1

4

4

*1

S4 *1

5

5 *1

T=1/fsys =2/fosc

(fsys : Internal system clock frequency)

SIO

322T [s]

*1 Instruction set the General output ports or output the Key scan signals (refer (1)Instruction (n)General output port

/ Key scan select)

Key scan cycle and the timing of Key data read out request are constant in any Power save mode.

Ver.2003-05-09

- 15 -

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