Basic Digital Display : Seven Segment

Seven segment is a display component that have seven segments(actually eight). Each segment represented by a LED. Seven-segment displays are widely used in digital clocks, electronic meters, and other electronic devices for displaying numerical information. Beside seven segment, there are fourteen-segment and sixteen-segment, usually used for making an alphanumeric character.

The segments of a 7-segment display are referred to by the letters A to G, as shown to the right, where the optional DP decimal point (an "eighth segment") is used for the display of non-integer numbers.

The animation to the right cycles through the common glyphs of the ten decimal numerals and the six hexadecimal "letter digits" (A–F). It is an image sequence of a "LED" display, which is described technology-wise in the following section. Notice the variation between uppercase and lowercase letters for A–F; this is done to obtain a unique, unambiguous shape for each letter.

As shown to the right, a seven-segment has ten pins under the display. Based on the pins, seven segment can be divided into 2 kinds, common cathode and common anode. A common anode seven segment consists of 2 pins of anode and 8 pins of cathode. Each cathode pin lead to cathode part of each segment(LED) on the display. Both of anode pins are short-circuited, and lead to anode part of each segment(LED). A common cathode seven segment is the opposite of a common anode seven segment. There are 2 pins of cathode and 8 pins of anode.

The image on the right is the pins of the seven-segment. X is the common pin, if it is a common anode, then X is anode, and vice versa. The other pins are the complement of the common. For the common anode, to turn the LED on, we must place the plus sign of the battery on the common and the minus sign of the battery on other pins.