Seven-segment LCD uses two-wire interface

You can connect seven-segment LCDs using only a two-wire interface. The two-wire interface may be at the field-effect, direct-drive LCD or at a serial interface (such as I2C) that uses an eight-pin microcontroller. The design uses an Atmel ATtinyl2 microcontroller, IC(sub 1). V(sub CC) can range fro...

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Bibliographic Details
Published in:EDN 2003-09, Vol.48 (19), p.89-89
Main Author: Krobath, Hans
Format: Magazinearticle
Language:English
Subjects:
Design and construction
Electronics
Liquid crystal displays
Semiconductors
Software
Wire
Online Access:Get full text
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Summary:You can connect seven-segment LCDs using only a two-wire interface. The two-wire interface may be at the field-effect, direct-drive LCD or at a serial interface (such as I2C) that uses an eight-pin microcontroller. The design uses an Atmel ATtinyl2 microcontroller, IC(sub 1). V(sub CC) can range from 2.7 to 5.5V. Each digit receives drive from an 8-bit 74HC164 shift register, which provides seven outputs for each of the segments and one output for a decimal point or a colon. The data input to the shift register drives the LCD's common terminal. Software for the eight-pin microcontroller generates the required symmetrical ac square wave between the segments and the common terminal.
ISSN:0012-7515
2163-4084