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18 LCD DRIVER (LCD8B)
18.5.6 Partial Common Output Drive
By setting the LCD8COMC*.COMxDEN bit (x = COM No.) to 0, any common outputs can be set to off waveform
regardless of the display data RAM contents. The partial common output drive function limits the display to the re-
quired area only to reduce power consumption.
18.5.7 n-Segment-Line Inverse AC Drive
The n-line inverse AC drive function may improve the display quality when being reduced such as when cross-
talk occurs. To activate the n-line inverse AC drive function, select the number of lines to be inverted using the
LCD8TIM2.NLINE[2:0] bits. The setting value should be determined after being evaluated using the actual circuit
board. Note that using the n-line inverse AC drive function increases current consumption.
COM0
LCD8TIM2.NLINE[2:0] bits = 0x00
(Normal drive)
COM0
LCD8TIM2.NLINE[2:0] bits = 0x03
(3-line inverse drive)
SEGx
LCD8TIM2.NLINE[2:0] bits = 0x00
(Normal drive)
SEGx
LCD8TIM2.NLINE[2:0] bits = 0x03
(3-line inverse drive)
Figure 18.5.7.1 1/8 Duty (1/3 bias) Normal Drive Waveform and 3-line Inverse Drive Waveform
18.6 Display Data RAM
The display data RAM is located beginning with address 0x7000.
The correspondence between the memory bits of the display data RAM and the common/segment pins varies de-
pending on the selected conditions below.
• Drive duty (1/8 to 1/2 or static drive)
• Segment pin assignment (normal or inverse)
• Common pin assignment (normal or inverse)
Figures 18.6.3.1 to 18.6.3.4 show the correspondence between display data RAM and the common/segment pins in
some drive duties.
Writing 1 to the display data RAM bit corresponding to a segment on the LCD panel turns the segment on, while
writing 0 turns the segment off. Since the display memory is a RAM allowing reading and writing, bits can be con-
trolled individually using logic operation instructions (read-modify-write instructions).
The area unused for display can be used as general-purpose RAM.
18.6.1 Display Area Selection
In the display data RAM, two screen areas can be allocated and the LCD8DSP.DSPAR bit can be used to switch
between the screens. Setting the LCD8DSP.DSPAR bit to 0 selects display area 0; setting to 1 selects display area 1.
18-10
Table 18.5.7.1 Selecting Number of Inverse Lines
LCD8TIM2.NLINE[2:0] bits
0x7
:
0x1
0x0
0
1
2
3
4
Seiko Epson Corporation
Number of inverse lines
7 lines
:
1 line
Normal drive
5
6
7
0
1
2
3
S1C17W14/W16 TECHNICAL MANUAL
4
5
6
7
V
C3
V
C2
V
C1
V
SS
V
C3
V
C2
V
C1
V
SS
V
C3
V
C2
V
C1
V
SS
V
C3
V
C2
V
C1
V
SS
(Rev. 1.2)
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