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23 LCD Driver (LCD8)
23-12
EPSON
S1C17602 TECHNICAL MANUAL
23.6 Display Control
23.6.1 Display On/Off
The LCD display state is controlled using DSPC[1:0] (D[1:0]/LCD_DCTL register).
DSPC[1:0]: LCD Display Control Bits in the LCD Display Control (LCD_DCTL) Register (D[1:0]/0x50a0)
Table 23.6.1.1: LCD display control
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 feed must be underway at the time. (See section
23.3.)
If display off is selected, the drive voltage feed from the LCD constant-voltage circuit stops, and pins VC1 to VC3
are all set to VSS level.
Since All on and All off directly control the driving waveform output by the LCD driver, display memory data is
not altered. Common 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 initial resetting or when the slp instruction is executed.
At the time of slp instruction execution, DSPC[1:0] is 0x0 (Display Off) during execution and returns to setting
value after returning.
23.6.2 LCD Contrast Adjustment
The LCD contrast can be adjusted to one of 16 gray levels using LC[3:0] (D[3:0]/LCD_CADJ register). Contrast is
adjusted by controlling the voltages VC1 to VC3 output by the internal LCD voltage circuit.
LC[3:0]: LCD Contrast Adjustment Bits in the LCD Contrast Adjust (LCD_CADJ) Register (D[3:0]/0x50a1)
Table 23.6.2.1: LCD contrast adjustment
LC[3:0]
Contrast
0xf
High (dark)
0xe
:
0x1
0x0
Low (light)
(Default: 0x0)
LC[3:0] is set to 0x7 after initial resetting. Initialization via software is required to achieve the required contrast.
23.6.3 Inverted Display
The LCD display can be inverted (black/white inversion) using merely control bit manipulation, without changing
the display memory. Setting DSPREV (D4/LCD_DCTL register) to 0 inverts the display; setting to 1 returns the
display to normal status.
DSPREV: Reverse Display Control Bit in the LCD Display Control (LCD_DCTL) Register (D4/0x50a0)
Note that the display will not be inverted if All off is selected using DSPC[1:0] (D[1:0]/LCD_DCTL register). The
display will be inverted if All on is selected