One Digit 7-Segment LED Display

One digit seven segment displays are used in many embedded system and industrial applications where the range of outputs to be shown is known beforehand. Basic 1 digit seven segment display can show numbers from 0-9 and a few characters. 7 segment displays are of different types; especially they differ in the number of digits/character it can display. Basically a 7 segment display is a single unit, which can display only 1 digit or 1 character. More digits are displayed by multiplexing single unit 7 segment displays together to form 2 digit display, 3 digit display or 4 digit 7 segment display. Its quiet easy to interface Arduino and 7 Segment display together! Lets begin the tutorial.

A 7 segment display has many limitations, especially in the range of characters it can display.There are displays in market which are much more advanced than seven segment displays and can display almost every character in the alphabet. For example:- a 16×2 LCD – which can display almost all ASCII characters. You might think why 7 segment display still exist in market. Well, 7 segment displays are the cheapest option when it comes to display devices available in market. A single digit/character 7 segment display unit is available at 1/10th of the cost of a 16×2 LCD module.

Each of the LEDs in the display is given a positional segment with one of its connection pins led out from the rectangular plastic package. These LED pins are labeled from “a” through to “g” representing each individual LED. The other LED pins are connected together forming a common pin. So by forward biasing the appropriate pins of the LED segments in a particular order, some segments will brighten and others stay dim, thus showing the corresponding character on the display.

The common pin of the display generally tells its type. There are two types of pin connection: a pin of connected cathodes and one of connected anodes, indicating Common Cathode (CC) and Common Anode (CA). As the name suggests, a CC display has all the cathodes of the 7 LEDs connected when a CA display has all the anodes of the 7 segments connected.