23 lCD DRiVeR (lCD)
S1C17624/604/622/602/621 TeChniCal Manual
Seiko epson Corporation
23-13
Display Control
23.6
Display On/Off
23.6.1
The LCD display state is controlled using DSPC[1:0]/LCD_DCTL register.
6.1.1 LCD Display Control
Table 23.
DSPC[1:0]
lCD display
0x3
All off (static)
0x2
All on (dynamic)
0x1
Normal display
0x0
Display off
(Default: 0x0)
For normal display, set DSPC[1:0] to 0x1. Note that the clock must be supplied. (See Section 23.3.)
If “Display off” is selected, the drive voltage supplied from the LCD system voltage regulator stops, and the V
C1
to
V
C3
pins are all set to V
SS
level.
Since “All on” and “All off” directly control the driving waveform output by the LCD driver, display memory data
is not altered. COM pins are set to dynamic drive for “All on” and to static drive for “All off.” This function can be
used to make the display flash on and off without altering the display memory.
DSPC[1:0] is reset to 0x0 (Display off) after an initial reset.
DSPC[1:0] is also reset to 0x0 when the
slp
instruction is executed and it reverts to the previous setting after
SLEEP mode is canceled.
lCD Contrast adjustment
23.6.2
The LCD contrast can be adjusted to one of 16 levels using LC[3:0]/LCD_CADJ register. Contrast is adjusted by
controlling the voltages V
C1
to V
C3
output by the internal LCD system voltage regulator.
6.2.1 LCD Contrast Adjustment
Table 23.
lC[3:0]
Contrast
0xf
High (dark)
0xe
↑
:
:
0x1
↓
0x0
Low (light)
(Default: 0x7)
LC[3:0] is set to 0x7 after an initial reset. Initialization via software is required to achieve the required contrast.
inverted Display
23.6.3
The LCD display can be inverted (black/white inversion) using merely control bit manipulation, without changing
the display memory. Setting DSPREV/LCD_DCTL register to 0 inverts the display; setting to 1 returns the display
to normal status.
Note that the display will not be inverted if “All off” is selected using DSPC[1:0]. The display will be inverted
when “All on” is selected.