PT6552 Datasheet, PDF (14/22 Pages) Princeton Technology Corp – ½ Duty LCD Driver with On-Chip Key Input Function

PT6552
NOTE ON CONTROLLER KEY DATA READ TECHNIQUES
When determining key on/off and reading key data, the controller must confirm the state of D0 output when CE is low for
each period t7. When DO is low, the controller recognizes that a key has been pressed and reads the key data. During
this operation t7 must obey the following condition:
t7 > t5 + t6 + t4 If key data is read when DO is high, the key data (KD1 to KD30) and the sleep acknowledge data (SA) will
be invalid.
1. CONTROLLER KEY DATA READING UNDER TIMER CONTROL
FLOWCHART
TIMING CHART
T=1/fosc
t3: Key scan execution time (800T [s]) when the key scan data for two key scans agrees.
t4: Key scan execution time (1600T [s]) when the key scan data for two key scans does not agree and a key scan is
executed again.
t5: Key address (43H) transfer time.
t6: Key data read time.
V1.3
14
July 2010