All About 7-Segment Display

7-Segment display driving from Arduino
7-Segment display driving from Arduino

What is 7-Segment display

The 7-segment displays are really just seven LEDs lined up in a particular pattern. In this case, the number ‘8’ shape we’re all familiar with. Each of the seven LEDs is called a segment because when illuminated the segment forms part of a numerical digit (both Decimal and Hex) to be displayed. An additional 8th LED is sometimes used for indication of a decimal point.

Types of 7-Segment display

There are two types of seven segment displays available in the market. According to the type of application, these displays can be used. The two configurations of seven segment displays are discussed below.

  • Common Anode Display
  • Common Cathode Display

Common Cathode 7-segment Display

Common Cathode 7 Segment Working
Common Cathode 7 Segment Working

In this type of display, all the cathode connections of  the LED segments are connected together to logic 0 or ground. The separate segments are lightened by applying the logic 1 or HIGH signal through a current limiting resistor to forward bias the individual anode terminals a to g.

Common Anode 7-segment Display

Common Anode 7 Segment Working
Common Anode 7 Segment Working

In this type of display, all the anode connections of the LED segments are connected together to logic 1. The separate segments are lightened by applying of the logic 0 or LOW signal through a current limiting resistor to the cathode of the particular segment a to g.

7-Segment Display Pinout

Now let’s go over the segment configuration so we know which pins light up which segments. The pinout for the 7-segment display is as follows.

7-segment display pinout
7-segment display pinout

COM pins are internally connected to form a common pin. This pin should be connected to GND (common cathode) or 5V (common anode) depending upon the type of the display.

How 7-Segment Display Works?

Depending upon the decimal digit to be displayed, the particular set of LEDs is illuminated. For instance, to display the numerical digit 4, we will need to light up four of the LED segments corresponding to b, c, f and g. Thus the various digits from ‘0 through 9’ and characters from ‘A through F’ can be displayed using a 7-segment display as shown.

Reference:

1. https://www.elprocus.com/types-of-7-segment-displays-and-controlling-ways/

2. https://lastminuteengineers.com/seven-segment-arduino-tutorial/

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