S3C8245/P8245/C8249/P8249 LCD CONTROLLER/DRIVER
14-5
LCD MODE REGISTER (LMOD)
The LCD mode control register LMOD is mapped to RAM addresses D1H.
LMOD controls these LCD functions:
Duty and bias selection (LMOD.3–LMOD.0)
LCDCK clock frequency selection (LMOD.5–LMOD.4)
The LCD clock signal, LCDCK, determines the frequency of COM signal scanning of each segment output. This is
also referred to as the 'frame frequency.' Since LCDCK is generated by dividing the watch timer clock (fw), the watch
timer must be enabled when the LCD display is turned on. Reset clears the LMOD register values to logic zero. This
produces the following LCD control settings:
Display is turned off
LCDCK frequency is the watch timer clock (fw)/29 = 64 Hz
The LCD display can continue to operate during idle and stop modes if a subsystem clock is used as the watch
timer source. The LCD output voltage level is always 3 V, supplied by the voltage booster.
Table 14-3. LCD Clock Signal (LCDCK) Frame Frequency
LCDCK Frequency Static 1/2 Duty 1/3 Duty 1/4 Duty
fw/29 (64 Hz) 64 32 21 16
fw/28 (128 Hz) 128 64 43 32
fw/27 (256 Hz) 256 128 85 64
fw/26 (512 Hz) 512 256 171 128
NOTE: ‘fw’ is the watch timer clock frequency of 32.768 kHz.