Chapter 8 LCD Module (S08LCDLPV1)
MC9S08LG32 MCU Series, Rev. 5
Freescale Semiconductor
183
9.4.2
LCDWF Registers
For a segment on the LCD panel to be displayed, data must be written to the LCDWF registers. For LCD
pins enabled as frontplanes, each bit in the LCDWF registers corresponds to a segment on an LCD panel.
The different phases A-H represent the different backplanes of the LCD panel. The selected LCD duty
cycle controls the number of implemented phases. Refer to
for normal LCD operation the
phases follow the sequence shown.
For LCD pins enabled as a backplane, the LCDWF assigns the phase in which the backplane pin is active.
This is how backplane assignment is done.
An example of normal operation follows: enable LCD pin 0 to operate as backplane 0. Enable the LCD
pin 0 by setting PEN0 bit in the LCDPEN0 register. Configure LCD pin 0 as a backplane pin by setting
the BPEN0 bit in the LCDBPEN0 register. Finally, the BPALCD0 bit in the LCDWF0 is set to associate
LCD pin 0 with backplane phase A. This will configure LCD0 to operate as a backplane that is active in
Phase A.
For LCD pins enabled as a frontplane, writing a 1 to a given LCDWF location results in the corresponding
display segment being driven with the differential root mean square (RMS) voltage necessary to turn the
segment on during the phase selected. Writing a 0 to a given location results in the corresponding display
segment being driven with the differential RMS voltage necessary to turn the segment off during the phase
selected.
9.4.3
LCD Display Modes
The LCD module can be configured to implement several different display modes. The bits ALT and
BLANK in the LCD-blink-control register (LCDBCTL) configure the different display modes. In normal
display mode (default), LCD segments are controlled by the data placed in the LCDWF registers, as
described in
Section 9.4.2, “LCDWF Registers
.” For blank-display mode, the LCDWF data is bypassed
and the frontplane and backplane pins are configured to clear all segments.
For alternate-display mode, the backplane sequence is modified for duty cycles of 1/4, 1/3, 1/2, and 1/1.
For four backplanes or less, the backplane sequence is modified as shown below. The altered sequence
allows two complete displays to be placed in the LDCDWF registers. The first display is placed in phases
A-D and the second in phases E-H in the case of four backplanes. If the LCD duty cycle is five backplanes
or greater, the ALT bit is ignored and creates a blank display. Refer to
for additional
information.
Using the alternate display function an inverse display can be accomplished for x4 mode and less by
placing inverse data in the alternate phases of the LCDWF registers.
Table 9-15. Alternate Display Backplane Sequence
Duty
Backplane Sequence
Alt. Backplane Sequence
1/1
A
E
1/2
A B
E F
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Страница 26: ...Chapter 1 Device Overview MC9S08LG32 MCU Series Rev 5 26 Freescale Semiconductor...
Страница 40: ...Chapter 2 Pins and Connections MC9S08LG32 MCU Series Rev 5 40 Freescale Semiconductor...
Страница 96: ...Chapter 5 Resets Interrupts and General System Control MC9S08LG32 MCU Series Rev 5 96 Freescale Semiconductor...
Страница 296: ...Chapter 12 Serial Peripheral Interface S08SPIV4 MC9S08LG32 MCU Series Rev 5 296 Freescale Semiconductor...
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