f
=
Blink
f
ACLK/VLOCLK/REFOCLK/LFXTCLK
(LCDB 1) × 2
9+LCDBLKPREx
LCD_F Controller Architecture and Operation
1001
SLAU356I – March 2015 – Revised June 2019
Copyright © 2015–2019, Texas Instruments Incorporated
LCD_F Controller
27.2.5.4 LCD Blinking
The LCD controller also supports blinking. The blinking mode LCDBLKMODx = 01 allows blinking of
individual segments, with LCDBLKMODx = 10 all segments are blinking, and with LCDBLKMODx = 00
blinking is disabled.
27.2.5.4.1 Blinking Memory
A separate blinking memory is implemented to select the blinking segments. To enable individual
segments for blinking, the corresponding bit in the blinking memory LCDBMx registers must be set. The
memory uses the same structure as the LCD memory shown in
. Each memory bit
corresponds to one LCD segment or is not used, depending on the multiplexing mode LCDMXx. To
enable blinking for a LCD segment, its corresponding memory bit is set.
The blinking memory can also be accessed word-wise using the even addresses starting at LCDBM0,
LCDBM4, ...
Setting the bit LCDCLRBM clears all blinking memory registers. It is automatically reset after the registers
are cleared.
27.2.5.4.2 Blinking Frequency
The blinking frequency f
BLINK
is selected with the LCDBLKPREx and LCDBLKDIVx bits. The same clock is
used as selected for the LCD frequency f
LCD
. The resulting f
BLINK
frequency is calculated by
.
(16)
The divider generating the blinking frequency f
BLINK
is reset when LCDBLKMODx = 00. After a blinking
mode LCDBLKMODx = 01 or 10 is selected, the enabled segments or all segments go blank at the next
frame boundary and stay off for half of a BLKCLK period. Then they go active at the next frame boundary
and stay on for another half BLKCLK period before they go blank again at a frame boundary.
NOTE:
Blinking Frequency Restrictions
The blinking frequency must be smaller than the frame frequency f
Frame
.
The blinking frequency should only be changed when LCDBLKMODx = 00.
27.2.5.4.3 Dual Display Memory
The blinking memory can also be used as a secondary display memory when no blinking mode
LCDBLKMODx = 01 or 10 is selected. The memory to be displayed can be selected either manually using
the LCDDISP bit or automatically with LCDBLKMODx = 11.
With LCDDISP = 0, the LCD memory is selected, and with LCDDISP = 1 the blinking memory is selected
as display memory. Switching between the memories is synchronized to the frame boundaries.
With LCDBLKMODx = 11 the LCD controller switches automatically between the memories using the
divider to generate the blinking frequency. After LCDBLKMODx = 11 is selected, the memory to be
displayed for the first half a BLKCLK period is the LCD memory. In the second half, the blinking memory is
used as display memory. Switching between the memories is synchronized to the frame boundaries.
27.2.5.4.4 COM Assignment During Dual Display and Blinking Modes
When LCDBLKMODx = 00, The COM number assignment is taken from the currently active memory
which is selected by the bit LCDDISP
When LCDBLKMODx = 01, 10 or 11, the COM assignment is taken from the Main Display memory.
Do not clear the active memory by the LCDCLRM or LCDCLRBM bit, as the COM assignment is also
cleared, which leads to unpredictable behavior. TI recommends clearing the inactive memory only using
this bit based on the display mode and display state.