16 lCD DRiVeR (lCD)
S1C17153 TeChniCal Manual
Seiko epson Corporation
16-3
(Rev. 1.0)
Frame Signal
16.3.2
The LCD driver generates the frame signal by dividing LCLK. The clock division ratio can be set using FRM-
CNT[1:0]/LCD_CCTL register. Figures 16.4.2.1 to 16.4.2.4 show one cycle of the frame frequency as “1 frame.”
Tables 16.3.2.1 and 16.3.2.2 list the frame frequencies that can be programmed.
When the clock source is OSC1a
3.2.1 Frame Frequency Settings (when the clock source is OSC1A = 32.768 kHz (LCLK = 512 Hz))
Table 16.
Drive duty
(lDuTY[2:0] setting)
FRMCnT[1:0] setting (lClK division ratio)
0x0
0x1
0x2
0x3
1/4 duty (0x3)
128 Hz (1/4)
64 Hz (1/8)
*
42.67 Hz (1/12)
32 Hz (1/16)
1/3 duty (0x2)
85.33 Hz (1/6)
56.89 Hz (1/9)
42.67 Hz (1/12)
34.13 Hz (1/15)
1/2 duty (0x1)
128 Hz (1/4)
64 Hz (1/8)
42.67 Hz (1/12)
32 Hz (1/16)
Static (0x0)
128 Hz (1/4)
64 Hz (1/8)
42.67 Hz (1/12)
32 Hz (1/16)
*
Default setting
When the clock source is OSC3B
3.2.2 Frame Frequency Settings (when the clock source is OSC3B)
Table 16.
Drive duty
(lDuTY[2:0] setting)
FRMCnT[1:0] setting
0x0
0x1
0x2
0x3
1/4 duty (0x3)
f
OSC3B
×
LCDTCLKD
–––––––– ––––––––
4
f
OSC3B
×
LCDTCLKD
*
–––––––– ––––––––
8
f
OSC3B
×
LCDTCLKD
–––––––– ––––––––
12
f
OSC3B
×
LCDTCLKD
–––––––– ––––––––
16
1/3 duty (0x2)
f
OSC3B
×
LCDTCLKD
–––––––– ––––––––
6
f
OSC3B
×
LCDTCLKD
–––––––– ––––––––
9
f
OSC3B
×
LCDTCLKD
–––––––– ––––––––
12
f
OSC3B
×
LCDTCLKD
–––––––– ––––––––
15
1/2 duty (0x1)
f
OSC3B
×
LCDTCLKD
–––––––– ––––––––
4
f
OSC3B
×
LCDTCLKD
–––––––– ––––––––
8
f
OSC3B
×
LCDTCLKD
–––––––– ––––––––
12
f
OSC3B
×
LCDTCLKD
–––––––– ––––––––
16
Static (0x0)
f
OSC3B
×
LCDTCLKD
–––––––– ––––––––
4
f
OSC3B
×
LCDTCLKD
–––––––– ––––––––
8
f
OSC3B
×
LCDTCLKD
–––––––– ––––––––
12
f
OSC3B
×
LCDTCLKD
–––––––– ––––––––
16
*
Default setting
f
OSC3B
: OSC3B clock frequency
LCDTCLKD: OSC3B division ratio (1/1024 to 1/8192)
The frame signal generated can be output to an external device via the LFRO pin. However, the output pin must be
switched for LFRO output using the port function select bit, as the pin is configured for an I/O port by default. For
detailed information on pin function switching, see the “I/O Ports (P)” chapter.
Drive Duty Control
16.4
Drive Duty Switching
16.4.1
Drive duty can be set to 1/4, 1/3, 1/2 or static drive using LDUTY[2:0]/LCD_CCTL register. Table 16.4.1.1 shows
the correspondence between LDUTY[2:0] settings, drive duty, and maximum number of display segments.
4.1.1 Drive Duty Settings
Table 16.
lDuTY[2:0]
Duty
Valid COM pins
Valid SeG pins
Max. number of
display segments
0x7–0x4
Reserved
–
–
–
0x3
1/4
COM0 to COM3
SEG0 to SEG31
128 segments
0x2
1/3
COM0 to COM2
SEG0 to SEG31
96 segments
0x1
1/2
COM0 to COM1
SEG0 to SEG31
64 segments
0x0
Static
COM0
SEG0 to SEG31
32 segments
(Default: 0x3)
The drive bias is fixed at 1/3 (three potentials V
C1
, V
C2
, V
C3
) for all duty settings.