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18.4 Registers of the LCD Controller Driver
Table 18.4-1 Functions of Each Bit in LCDC Control Register 1 (LCR1)
Bit name
Function
Bit 7
CSS:
Frame cycle generating
clock selection bit
This bit selects the clock for generating the LCD display
frame cycle (for driving duty).
When this bit is "0," the LCD controller driver is operated
on the output of the time base timer that is the main clock
oscillation frequency divided by 2
8
. When this bit is "1," it
is operated on the subclock
Note:
In main stop and subclock modes, the LCD controller
driver cannot be operated on the output of the time base
timer because oscillation of the main clock is stopped. To
operate the LCD controller driver on the subclock, check
that the subclock is fully stabilized before switching to the
subclock.
Reference:
Even if the rate of the main clock is switched (gear
function) when the LCD controller driver is operating on
the timer base timer, the frame frequency is not affected.
Bit 6
LCDEN:
Watch mode time operation
enable bit
This bit selects whether the LCD controller driver is
operated in watch mode.
When this bit is "1," LCD display continues even after
moving to the watch mode.
When this bit is "0," LCD display is stopped in watch
mode.
Note:
To operate LCD display even in watch mode, the
subclock (CSS = 1) must be selected.
Bit 5
VSEL:
LCD driving power supply
control bit
This bit selects whether the internal dividing resistors are
energized.
When this bit is "0," the internal dividing resistors are shut
off; when this bit is "1," the resistors are energized. To
connect external dividing resistors, this bit must be set to
"0."
Bit 4
BK:
Display blanking selection
bit
This bit selects whether or not the LCD is displayed.
In display blanking (non-display, BK = 1), the segment
output indicates a non-selected waveform (a waveform
that is out of the display condition).
Bit 3
Bit 2
MS1, MS0:
Display mode selection bits
These bits select the duty of the output waveform from
three types.
The operating common pins are determined in
accordance with the selected duty output mode.
When these bits are "00B," the LCD controller driver stops
display.
Note:
When the selected frame cycle generating clock stops
due to a shift to the top mode or otherwise, stop the
display operation in advance.