NJU6535 데이터 시트보기 (PDF) - Japan Radio Corporation

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NJU6535

1/3 , 1/4 Duty LCD Driver

Japan Radio Corporation  

NJU6535

(6-5) Normal mode

Key scan operates with follows in normal mode.

1, Key scan signal output terminals S0 – S5 output “H” signals when key scan does not operate, and output key scan

signals after start of key scan operation. The conditions of key scan signal input terminals K0 – K4 are “L” state with

internal pull-down resistances, though “H” signal comes in to K0 – K4 corresponding to the turned on keys.

2, The function of key scan starts twice operations when any key is turned on. It stops when a couple of data by

continuously twice key scan operations are accorded and fixed as a correct key status. It operates more 2 times when

the key status is not fixed and any keys are still turning on. It repeats again and again until key status is fixed. The correct

key status data is stored and newly key scan operation does not start until external CPU reads data out after key status is

fixed.

3, When the key status is fixed, SO terminal outputs “L” signal as Key data read out request to CPU. CPU should read key

data out at detection of this “L” signal. If CPU writes the display data or instructions to the NJU6535 when SO terminal

outputs “L” signal, SO terminal outputs “H” level during “CE” terminal is ”H”.

4, The Key data read out request signal is released and SO terminal outputs “H” signal after finish of CPU key data read

out for newly key scan operation.

SO terminal requires pull up resistor (1 Kohm to 10 Kohms) because of Open drain type output. Multiple data of key are

output in case of key more input so that CPU should process the data by itself.

Key scan example (Normal mode)

Key input 1

T = 1 / fosc

Key input 2

Key scan

CE

577T[s]

577T[s]

577T[s]

SCL

SI

Data send

Data send

SO

Key data read

request

Data send

Key data read

Key data read

Key data read

request

Key data read

Key data read

request

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