HD66712 Datasheet, PDF (72/88 Pages) Hitachi Semiconductor – Dot-Matrix Liquid Crystal Display Controller/Driver

HD66712U
Low Power Mode
When the extension driver is not used (EXT = Low) with extension register enabled (RE = 1), the
HD66712 enters low power mode by setting the low-power mode bit (LP) to 1. During low-power mode,
as the internal operation clock is divided by 2 (2-line/4-line display mode) or by 4 (1-line display mode),
the execution time of each instruction becomes two times or four times longer than normal. In addition,
as the frame frequency decreases to 5/6, display quality might be affected.
In addition, since the display is not shifted in low power mode, display shift must be cleared with the
return home instruction before setting low power mode. The amount of horizontal scroll must also be
cleared (HDS = 000000). Moreover, because the display enters a shift state after clearing low-power
mode, the home return instruction must be used to clear display shift at that time.
Return home
Extended register enable
Clear horizontal scroll quantity
HDS = 000000
Set a low power mode
Return home
RS R/W DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0
0000000 010
RS R/W DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0
0 0 0 0 1 DL N 1 BE 0
RS R/W DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0
0 0 1 0 00 0 0 0 0
RS R/W DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0
0 0 0 0 1 DL N 1 BE 1
RS R/W DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0
00000000 10
Low power operation
Note: The execution time of an instruction in low-power
mode becomes two times or four times longer
then normal. The frame frequency also
decreases by 5/6.
Clear low power mode
RS R/W DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0
0 0 0 0 1 DL N 1 BE 0
Note: Up until this instruction, execution time is two
times or four times longer than normal.
Return home
RS R/W DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0
00000000 10
Note: Because the display enters a shift state, be sure
to execute this instruction.
Figure 33 Usage of Low Power Mode
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