NJU6535 データシートの表示（PDF） - Japan Radio Corporation

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NJU6535

1/3 , 1/4 Duty LCD Driver

Japan Radio Corporation  

NJU6535

(6-4) Timing of Key scan

Key scan cycle is 288T[S]. 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 NJU6535 recognizes Key On and outputs “L”

level from SO terminal after 577T[S] from start of Key scan for a request to read key data out to external CPU. When the

SO terminals outputs “L” signal, the key scan does not operate until end of key data reading by CPU, 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 577T[S]

Key ON

288T[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

S5

6

6

SO

577T [s]

T = 1 / fosc

*1 Instruction data K0, K1 set the output ports to output the scan signals (refer (1)Instruction (2-4)Segment output / Key

scan selection)

Key scan cycle and the timing of Key data read out request are constant in any combination of S0, S1, K0 and K1.

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