AN1048 datasheet(5/21 Pages) STMICROELECTRONICS

Part #	AN1048

Description	ST7 software LCD driver

PDF	21 Pages

Scroll/Zoom	100%

Manufacturer	STMICROELECTRONICS [STMicroelectronics]

Direct Link	http://www.st.com

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5 / 21 page

AN1048

LCD drive signals

5/21

0 or VDD levels and to high impedance input mode for VDD/2. When one backplane is active,

the other one is neutralised by applying VDD/2 to it. This VDD/2 voltage is defined by two

resistors of equal value, externally connected to the I/O pin. By using an MCU with flexible

I/O pin configuration, a duplexed LCD drive can be implemented with only 2 external

resistors bridge (each on two com lines).

Figure 3.

Basic LCD Segment Connection in duplexed mode

Figure 4.

LCD signals for duplexed mode (used in the ST7 example)

COM1

COM2

S11

S12

COM1

S11=COM1-S1

+Vdd

S12=COM2-S1

+Vdd

COM2

CASE1

CASE2

CASE3

CASE4

+Vdd/2

-Vdd

+Vdd

+Vdd/2

-Vdd/2

-Vdd

+Vdd

+Vdd/2

-Vdd/2

SEGMENT1

SEGMENT2

OFF

AN1048 Datasheet(PDF) 5 Page - STMicroelectronics