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Guide to seven-segment displays commonly used with LED


Electronic display devices frequently employ a seven-segment display to show decimal numbers from 0 to 9 and, in some situations, simple characters. Seven-segment displays gained popularity because of light-emitting diodes (LEDs), while more recently liquid crystal displays (LCDs) have also become common. The most prevalent uses for electronic equipment that display numerical data include microwave ovens, calculators, washing machines, radios, digital clocks, etc.

What is a 7-segment display and how it works?

The seven-segment display is the oldest and most effective type of display utilized in embedded systems. There are only 8 LEDs inside this display. The figure above separates these eight LEDs into segments denoted as a, b, c, d, e, f, and DP. Each of these 8-segment LEDs has had one end of its pins removed from the module, while the other ends have been linked and removed as the Common pin, as seen above. Therefore, powering the joint pin and the segment pin is all needed to turn on an LED of a particular segment.
What-is-a-7-segment-display-and-how-it-worksBy lighting the required individual LEDs within the digit, the 7-segment display may function. You can freely use left pins to regulate the display. Once these pins are pushed forward in a row, it will show the desired alphabet or number. The segment pins are applied with logic zero or high depending on the seven-segment display kind, and the common pins are treated the same way.

A 7-segment display will display an 8 number once the power is turned on. If we turn off the power, especially for “g,” it will show as “0.”For instance, both segments b & c must be switched ON & the remaining segments will be switched off if you want to display the number “1”.

What are the types of 7-segment display?

Seven-segment displays come in two different varieties on the market. These displays can be employed depending on the application. Below is a discussion of the two seven-segment display configurations.

Common Anode Display

All LED segment anode connections in this display are linked to logic 1. Applying the logic 0 or LOW signal through a current-limiting resistor to the cathode of each segment, from a to g, lights up the individual segments.

Common Cathode Display

All this display’s LED segment cathode connection are wired to the ground or logic 0. The distinct segments are made lighter by applying the logic 1 or HIGH signal to the individual anode terminals a to go through a current-limiting resistor.

What is the advantage of seven segment?

7-segment displays have some benefits, including

●Cheap, very well-liked, and structured.

●A single driver IC can drive all the digits since they share common cathodes or anodes (although usually, two separate driver ICs are used – one for the cathodes and one for the anodes). The driver ICs are simple to link with microcontrollers in digital systems because they can sink or source current from a microcontroller output pin.

●Each digit has several LEDs, making it simple to read them from a distance or in poor light.

●For each digit, only four signal lines are needed (one signal line for each segment, plus one signal line to select the digit). They are thus simpler to put into practice.What-is-the-advantage-of-seven-segment

Where are 7-segment displays used?

The seven-segment display can be used for the following things.

➔Most electronic meters, digital calculators, clock radios, seven-segment displays, digital clocks, odometers, etc., employ them.
➔Most seven-segment display applications currently use LCDs because of their low power requirements.

Seven-segment displays are often used in digital clocks, electronic meters, simple calculators, displays in home appliances, autos, and several other electronic devices that show numerical data.

What are the parts of a 7-segment display?

The following are the components of the seven-segment display LED:

●Components that emit light (a–g): Segments (Sag) (Seg)

●The component that emits dots of light: Final digit (DP)

●The seven segments display are generally referred to as: Digits (Dig) (Dig)

How are 7-segment displays wired?


One of the connection pins for each segment LED is pulled out of the package’s rectangular plastic shape. The letters “a” through “g” is written on these pins’ labels. One common pin is created by connecting the remaining LED pins collectively.

Similar to a standard LED, each segment can be separately turned on or off by setting the associated pin to HIGH or LOW. You may build any numerical character and some straightforward letter representations by lighting up specific portions.

How do you power a 7-segment display?


Start with a power supply. It is advised to use power with a ground potential of between +3.6VDC and +5VDC, which can come from batteries or a benchtop power source. Run the ground and power to the corresponding rows of horizontal rails at the top of your breadboard.

Connect a resistor from the power rail to a breadboard column that is not currently being used. It makes no difference which way the resistor is facing. In this example, a 220 Ohm resistor is being used, but for mapping the display pins, any resistor between 180 and 1,000 Ohms should work.

Place the 7-Segment Display so that the center gutter dividing the breadboard separates the top row of pins from the lower pins. Next, join a jumper wire from the resistor to the display’s pin 1.

How do I test a 7-segment display?


Following are the steps to follow if testing a 7-segment display.

●Pin 1 will be visible when you hold the display in your hand.

●Set the multimeter to the appropriate continuity range after assuming a red lead for positive and a black lead for negative.

●Using a sound test, check your meter (touch both the leads together, and a sound will be produced). Your multimeter’s battery could occasionally degrade, making it incapable of properly displaying data at times. If this occurs, replace the multimeter’s batteries with fresh ones.

●Put the black lead of your multimeter on pins 3 or 8. Since they are connected internally, both are common pins.

●Now connect the red lead of your meter to any other pin, like 1 or 5.

●The display is a common cathode if any of its components glow.

●If none of the segments illuminates, switch the multimeter’s leads.

●Pin 3 or pin 8 should receive the red lead from your meter.

●Place the multimeter’s black lead on the last pin now. If any segment glows, the display is a common anode, in which case the positive pin is shared by all, and the remaining connections are made to a negative supply.

●To make sure the display is functioning properly, examine each segment of the common cathode and anode.

●If any of the seven segments display don’t glow, they are broken.

FAQ about seven segment display

Most frequent questions and answers

The sizes of this display range from 6 inches (15 cm) to an astounding 25 inches (63 cm), and it is visible even in the strongest sunlight. Since it has seven segments, you can display both digits and some letters on it.

Two 32-bit registers are set up as the seven-segment displays. Each register’s individual bytes individually turn on and off the appropriate display segments. Hexadecimal values must therefore be decoded in order to be displayed on displays.

The digits in digital watches, calculators, clocks, measuring devices, counters, etc., are typically displayed on seven-segment screens. Typically, the display output of numerical gures and characters is provided by LCD and LED segments.


7-segment displays are loved by electronics enthusiasts for their simplicity of use and ease of understanding. After reading this article, I hope it can be helpful to you. For other related information articles about PCB, PCBA and electronic components, and PCB design, you can browse the IBE website. Or if you need one-stop PCBA service, please contact us immediately.

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