Datasheet
Chapter 9 Liquid Crystal Display Driver (S08LCDV1)
MC9S08LC60 Series Data Sheet: Technical Data, Rev. 4
Freescale Semiconductor 141
The value of LCDCLK is important because it is used to generate the LCD module waveform base clock
frequency. Equation 9-1 provides an expression for the LCD module waveform base clock frequency
calculation. Equation 9-1 illustrates that the LCD module waveform base clock frequency also depends on
the LCLK[2:0] bit field.
The LCD module waveform base clock is the basis for the calculation of the LCD module frame frequency.
The LCD module frame frequency is a function of LCD module duty cycle as shown in Equation 9-6.
Table 9-15 shows LCD module frame frequency calculations considering several possible LCD module
configurations of LCLK[2:0] and DUTY[1:0]. The using LCD module frame frequency calculations a
based on LCD module clock input value approximately 32 kHz.
LCD module frame frequency = (LCD module waveform base clock) × (duty cycle) Eqn. 9-6
The LCD module frame frequency is defined as the number of times the LCD segments are energized per
second. The LCD module frame frequency must be selected to prevent the LCD display from flickering
(LCD module frame frequency is too low) or ghosting (LCD module frame frequency is too high). To
avoid these issues a LCD module frame frequency in the range of 30 to 100 Hz is required. LCD module
frame frequency less that 30 Hz or greater that 100 Hz are out of specification and invalid. Selecting lower
values for the LCD base and frame frequency results in lower current consumption for the LCD module.
9.4.1.4 LCD Waveform Examples
This section shows the timing examples of the LCD output waveforms for the available modes of
operation. As shown in Table 9-16, all examples use 1/3 bias mode.
Table 9-15. LCD Module Frame Frequency Calculations
1
,
2
1
LCD clock input ~ 32.768 kHz
2
Shaded table entries are out of specification and are invalid.
LCLK[2:0]
LCD Clock Input Divider
(16 × 2
LCLK[2:0]
)
LCD Base
Frequency
(Hz)
LCD Frame Frequency (Hz)
0 16 2049.3 1024 683 512.32
1 32 1024.7 512.32 341.55 256.16
2 64 512.3 256.16 170.77 128.08
3 128 256.2
128.08 85.38 64.04
4 256 128.1 64.04 42.69 32.02
5 512 64.0 32.02
21.34 16.01
6 1024 32.0 16.01 10.67 8.00
7 2048 16.0 8.00 5.33 4.00
Duty Cycle
1/2/ 1/3 1/4