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Seven Segment LCDs? Answered

http://i00.i.aliimg.com/photo/v0/325133078/7_segment_LCD_panel.jpg

Has anyone had any luck hooking up seven segment lcds to their arduino's? These have 4 seven segment digits, a :, and an am/pm display. They have less than 28 pins.

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steveastroukBest Answer (author)2012-04-24

LCDs have a bit of a trick to them, because they need AC to drive them. It doesn't take much, but you need to drive the backplane with a swtiching pin on the arduino. And of course, without a driver chip, you need a pin per segment + a mulltiplex.

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mpilchfamily (author)2012-04-24

First of all a seven segment display and an LCD are totally different types of displays. LCD stands for Liquid Crystal Display.

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http://i00.i.aliimg.com/photo/v0/325133078/7_segment_LCD_panel.jpg

"Seven-segment displays may use a liquid crystal display (LCD), arrays of light-emitting diodes (LEDs), or other light-generating or controlling techniques such as cold cathode gas discharge, vacuum fluorescent, incandescent filaments, and others." Thank You Wikipedia :)


Im talking about the LCD's that you would find in something like a coffe maker that displays the time in the format 12:12 am

They are capable of displaying 88:88 and am/pm



Sorry for the confusion

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rickharris (author)Michael_Bell2012-04-25

My microwave uses LED display However if you have LCD (Gery when off) then disregard my original post as it doesn't apply to LCD.

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No, you can buy 7 segment LCDs !!

http://uk.rs-online.com/web/p/lcd-displays-alphanumeric/2156442/

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rickharris (author)2012-04-24

Find a data sheet, You need to know if they are common anode or common cathode.

Beyond that you have a bunch of LEDs that just happen to be formatted in a numerical pattern so lighting them is straight forward.

As F'ard says to drive as a numerical display usually it is easier to use a driver chip - send the number in binary to the chip and it sorts out the logic for the display.

the 4026 is one such beast - Data sheet here

http://www.datasheetcatalog.org/datasheet/SGSThomsonMicroelectronics/mXwwry.pdf

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frollard (author)2012-04-23

You usually need to drive them with either a demultiplexer (you feed in one of 10 pins and it outputs the correct number for you), or drive the matrix yourself and decode the pins yourself.

relevant articles:

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