LC75864W View Datasheet(PDF) - SANYO -> Panasonic
Part Name
Description
Manufacturer
LC75864W Datasheet PDF : 26 Pages
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LC75864E, 75864W
Notes on the controller key data read techniques
1. Timer based key data acquisition
(1) Flowchart
Key data read
processing
(2) Timing chart
Key input
Key on
Key on
Key scan
CE
DI
DO
t5
t6
t5
t5
t8
Key
address
t7
Key data read
t8
t7
t8
t7
Key data read request
t9
t9
t9
t9
Controller determination Controller determination Controller determination Controller determination Controller determination
(Key on)
(Key on)
(Key off)
(Key on)
(Key off)
t5: Key scan execution time when the key data agreed for two key scans. (800 T (s))
t6: Key scan execution time when the key data did not agree for two key scans and the key scan was executed again. (1600 T (s))
1
T = fOSC
t7: Key address (43H) transfer time
t8: Key data read time
(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 t9 period without fail. If DO is low, the controller recognizes that a
key has been pressed and executes the key data read operation.
The period t9 in this technique must satisfy the following condition.
t9 > t6 + t7 + t8
If a key data read operation is executed when DO is high, the read key data (KD1 to KD30) and sleep acknowledge
data (SA) will be invalid.
No. 6860-24/26
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