LC75852E, 75852W
Notes on Controller Key Data Read Techniques
1. Controller key data reading under timer control
• Flowchart
• Timing Chart
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
1
T =
fOSC
• Description
When determining key on/off and reading key data, the controller must confirm the state of DO 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.
No. 4828-14/16
SANYO [ SANYO SEMICON DEVICE ]
