PT6530 Datasheet, PDF (35/42 Pages) Princeton Technology Corp – LCD Driver IC

PT6530
6.17 NOTE ON THE CONTROLLER KEY DATA READ TECHNIQUES
6.17.1 TIMER BASED KEY DATA ACQUISITION
FLOWCHART
TIMING CHART
t5: Key scan execution time when the key data agreed for two key scans. (615T(s))
t6: Key scan execution time when the key data did not agree for two key scans and the key scan was executed again.
(1230T(s))
t7: Key address (43H) transfer time
T
=
1
fosc
t8: Key data read time
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.
V1.3
35
June 2010