f
=
LCD
f
ACLK/VLOCLK
(L 1) × 2
LCDPRE
7
6
5
4
3
2
1
0
Associated
Common Pins
Register
7
0
Associated
Segment Pins
Sn
--
--
--
--
--
--
LCDM15
14
--
--
14
--
--
--
--
--
--
LCDM14
13
--
--
13
--
--
--
--
--
--
LCDM13
12
--
--
12
--
--
--
--
--
--
LCDM12
11
--
--
11
--
--
--
--
--
--
LCDM11
10
--
--
10
--
--
--
--
--
--
LCDM10
9
--
--
9
--
--
--
--
--
--
LCDM9
8
--
--
8
--
--
--
--
--
--
LCDM8
7
--
--
7
--
--
--
--
--
--
--
--
LCDM7
6
6
n
1
1
--
--
--
--
--
--
--
--
LCDM2
2
2
--
--
--
--
--
--
--
--
LCDM3
3
3
--
--
--
--
--
--
--
--
LCDM4
4
4
--
--
--
--
--
--
--
--
LCDM5
--
--
--
--
--
--
5
--
--
5
LCDM6
--
--
--
--
--
--
LCDM16
--
--
15
15
--
--
--
--
--
--
LCDM17
--
--
16
16
--
--
--
--
--
--
LCDM18
--
--
17
17
--
--
--
--
--
--
LCDM19
--
--
18
18
--
--
--
--
--
--
LCDM20
--
--
19
19
0
0
--
--
--
--
--
--
--
--
LCDM1
LCD_C Operation
935
SLAU367P – October 2012 – Revised April 2020
Copyright © 2012–2020, Texas Instruments Incorporated
LCD_C Controller
36.2.1.2 5-Mux to 8-Mux Mode
For 5-mux to 8-mux modes, one byte of the LCD memory contains the information for one segment line.
shows an example LCD memory map for these modes with 160 segments.
Figure 36-3. LCD Memory for 5-Mux to 8-Mux Mode - Example for 160 Segments
36.2.2 LCD Timing Generation
The LCD_C controller uses the f
LCD
signal from the integrated clock divider to generate the timing for
common and segment lines. With the LCDSSEL bit, ACLK with a frequency between 30 kHz and 40 kHz
or VLOCLK can be selected as clock source into the divider. The f
LCD
frequency is selected with the
LCDPREx and LCDDIVx bits. The resulting f
LCD
frequency is calculated by:
The proper f
LCD
frequency depends on the LCD's requirement for framing frequency and the LCD multiplex
rate. It is calculated by:
f
LCD
= 2 × mux × f
Frame
For example, to calculate f
LCD
for a 3-mux LCD with a frame frequency of 30 Hz to 100 Hz:
f
Frame
(from LCD data sheet) = 30 Hz to 100 Hz
f
LCD
= 2 × 3 × f
Frame
f
LCD
(min) = 180 Hz
f
LCD
(max) = 600 Hz
With f
ACLK/VLOCLK
= 32768 Hz, LCDPREx = 011, and LCDDIVx = 10101:
f
LCD
= 32768 Hz / ((21+1) × 2
3
) = 32768 Hz / 176 = 186 Hz