LCD Driver (LCD64F6B)
MPC5606S Microcontroller Reference Manual, Rev. 7
Freescale Semiconductor 817
• 1/2 Duty (2 backplanes), 1/2 Bias (3 voltage levels)
• 1/2 Duty (2 backplanes), 1/3 Bias (4 voltage levels)
• 1/3 Duty (3 backplanes), 1/3 Bias (4 voltage levels)
• 1/4 Duty (4 backplanes), 1/3 Bias (4 voltage levels)
• 1/5 Duty (5 backplanes), 1/3 Bias (4 voltage levels)
• 1/6 Duty (6 backplanes), 1/3 Bias (4 voltage levels)
The voltage levels required for the different operating modes are generated internally based on selected
reference voltage. If VLCD as reference selected, changing VLCD alters the differential RMS voltage
across the segments in the ON and OFF states, thereby setting the display contrast.
The backplane waveforms are continuous and repetitive every frame. They are fixed within each operating
mode and are not affected by the data in the LCD RAM.
The frontplane waveforms generated are dependent on the state (ON or OFF) of the LCD segments as
defined in the LCD RAM. The LCD driver hardware uses the data in the LCD RAM to construct the
frontplane waveform to create a differential RMS voltage necessary to turn the segment ON or OFF.
The LCD duty is decided by the DUTY bits in the LCD Control Register (LCDCR). The number of bias
voltage levels is determined by the BIAS bit in the LCDCR. Table 22-29 summarizes the Multiplex modes
(duties) and the bias voltage levels that can be selected for each multiplex mode (duty). The backplane pins
have their corresponding backplane waveform output BP[m-1:0] in high impedance state when in the OFF
state as indicated in Table 22-29. In the OFF state the corresponding pins BP[m-1:0]can be used for other
functionality.
Table 22-29. LCD duty and bias
Duty
LCDCR Register Backplanes Bias Level
DUTY BP5 BP4 BP3 BP2 BP1 BP0 BIAS=0 BIAS=1
1/1 000 OFF ON 1/1
1/2 001 OFF ON 1/2 1/3
1/3 010 OFF ON 1/3
1/4 011 OFF ON 1/3
1/5 100 OFF ON 1/3
1/6 101 ON 1/3
1/6 110 ON 1/3
1/6 111 ON 1/3
To Next Page
Loading...
