[bill2009] wanted to reuse some common seven segment LCDs, but the question was how to drive them. Armed with a couple application notes from [Microchip] and [Atmel], an oscilloscope and an Arduino, he has made a proof of concept which shows its not super hard to drive those little reflective LCDs that so many devices have.
First finding out that these things are indeed multiplexed, he went on to what is needed to drive them, which is about +-2 volts difference from the backplane, next up was to find a donor, which he found readily at Staples, in the form of a “clocky” style run away alarm clock.
After poking around watching what signals do to the different segments on the LCD he whipped up a little circuit to control the display from the Arduino. The positive and negative voltages the segments require are made possible by the use of a set of pull down resistors, and switching pin modes on the micro controller.
These small type segmented LCDs are everywhere, and being able to use them is a big bonus.
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