LC75700T View Datasheet(PDF) - SANYO -> Panasonic
Part Name
Description
Manufacturer
LC75700T Datasheet PDF : 16 Pages
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LC75700T
Notes on the controller key data read techniques
1. Timer based key data acquisition
(1) Flowchart
CE = "L"
DO = "L"
NO
YES
Key data read
processing
(2) Timing chart
Key input
Key scan
CE
DI
DO
Key on
Key on
t3
t4
t3
t3
t6
Key
address
t5
Key data read
t6
t5
t6
t5
Key data read request
t7
Controller
determination
(Key on)
t7
Controller
determination
(Key on)
t7
Controller
determination
(Key off)
t7
Controller
determination
(Key on)
Controller
determination
(Key off)
t3: Key scan execution time when the key data agreed for two key scans (615T (s))
t4: Key scan execution time when the key data did not agree for two key scans and
the key scan was executed again. (1230T(s))
t5: Key address (63H) transfer time
t6: Key data read time
1
T= fosc
(3) Explanation
In this technique, the controller uses a timer to determine key on/off states and read the key data. The controller must
check the DO state when CE is low every t7 period without fail. If DO is low, the controller recognizes that a key has
been pressed and executed the key data read operation.
The period t7 in this technique must satisfy the following condition.
t7 > t4 + t5 + t6
If a keydata read operation is executed when DO is high, the read key data (KD1 to KD30) will be invalid.
No. 7632-14/16
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