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

(5-5) Normal mode

Key scan operates with follows in normal mode.

1, Key scan signal output terminals S0 – S4 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 MPU 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 MPU. MPU should read

key data out at detection of this “L” signal.

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

out for newly key scan operation.

SIO terminal requires pull up resistor because of Open drain type output. Multiple data of key are output in case of key

more input so that MPU should process the data by itself.

Key scan example (Normal mode)

Key input 1

T = 1 / fosc

Key input 2

Key scan

CE

322T[s]

322T[s]

322T[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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Ver.2003-05-09

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