PT6552

V1.3

14

July 2010

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.