GMS81C7216 Datasheet, PDF (71/121 Pages) List of Unclassifed Manufacturers – 8-BIT SINGLE-CHIP MICROCONTROLLERS

GMS81C7208/7216
18.2 Duty and Bias Selection of LCD Driver
5 kinds of driving methods can be selected by DTY (bits 3 and 2
of LCD Control Register and connection of VCL pin externally.
Figure 18-3 shows typical driving waveforms for LCD.).
VCL2
VCL1
VCL0
GND
-VCL0
-VCL1
-VCL2
1/f_F
Data “1”
Data “0”
(a) 1/4 duty, 1/3 bias
VCL2
VCL1
VCL0
GND
-VCL0
-VCL1
-VCL2
1/f_F
Data “1” Data “0”
(c) 1/2 duty,1/3 bias
VCL2
VCL1
VCL0
GND
-VCL0
-VCL1
-VCL2
1/f_F
Data “1”
(e) Static
Data “0”
VCL2
VCL1
VCL0
GND
-VCL0
-VCL1
-VCL2
1/f_F
Data “1”
Data “0”
(b) 1/3 duty, 1/3 bias
VCL2
VCL1 = VCL0
GND
-VCL0 = -VCL1
-VCL2
1/f_F
Data “1” Data “0”
(d) 1/2 duty, 1/2 bias
Note: f_F: LCD Frame Frequency
Figure 18-3 LCD Drive Waveform (Voltage COM-SEG Pins)
18.3 Selecting Frame Frequency
Frame frequency is set to the main frequency as shown in the fol-
lowing Table 18-1.
The LCK[1:0] of LCR determines the frequency of COM signal
scanning of each segment output. The watch timer must be en-
abled when the LCD display is turned on. RESET clears the LCD
control register LCR values to logic zero. The LCD display can
continue to operate even during the SLEEP and STOP modes.
.
LCK[1:0]
00
01
10
11
LCD clock
f_XIN÷2⁷÷32
f_XIN÷2⁷÷64
f_XIN÷2⁷÷128
f_XIN÷2⁷÷256
Frame Frequency (Hz)
(When f_XIN = 4.19 MHz)
1024
512
256
128
Table 18-1 Setting of LCD Frame Frequency
FEB. 2005 Ver 1.04
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