NJU6535 데이터 시트보기 (PDF) - Japan Radio Corporation

부품명

상세내역

일치하는 목록

NJU6535

1/3 , 1/4 Duty LCD Driver

Japan Radio Corporation  

NJU6535

(6-8) Key data reading out operation by external CPU

(a) Display data writing

Display data and instruction change operate at the rising edge of signal into CE terminal. Written data

or instructions do not operate during CE terminal “H”. When the time to write whole display data into Data

Buffer becomes too long by huge display data, display may be effected unexpected display. Data writing

order from Data 1 to Data 3 in 1/3 duty or Data 1 to Data 4 in 1/4 duty is not limited.

The duty is 1/3 after initialization. For 1/4 duty operation, Data 1 must be written first after initialization

(b) Key data reading out operation

The minimum period from Key in to SO terminal = “L” is 577T(t1) by key scan operation. When key scan

operation performs again for key data fix preventing from noise or bouncing of key, the period from Key in

to SO terminal = “L” is 1200T(t1). When the SO terminal outputs “L”, the key scan operation is stopped

after execution of key data reading out operation. Therefore, fixed key data is kept until end of key data

reading out operation. When key data reading out operation is performed during SO terminal = “H”, both

of key data from KD1 to KD30 and power save flag (PSF) are not outputted correctly.

Key data reading out operation example

The flowchart below shows an example of timer interrupt application. When SO terminal condition is “L”

after check of SO terminal condition at every timer interrupt operation, it is decided as Key In and key data

reading out operation is performed. When SO terminal condition is “H, it is decided as Key Off. For the

correct decision of Key Off, the timer interrupt cycle (1/t3) should be expanded over the time added with

[period of key scan (1200T in case of measure against key bouncing of key) and [period of key data

reading out operation (t2)]. In this time, the period of timer interrupt cycle (t3) must be set with enough

margin including the range of fosc.

Sequence of key data reading out operation

Timer

Yes

SO=”L”?

No

Key ON

Key OFF

Key data

read out

End of Timer

- 17 -

Share Link: