7-segment LED displays – what you should know about them

Date of publication: 26-10-2023 Update date: 10-04-2026 🕒 6 min read

In today's digitized world, displays of various types play an important role. They transmit information to us, help us navigate, enable communication and provide indispensable data. Among these extraordinarily useful devices, 7-segment LED displays have a special place due to their simplicity, readability and broad applications.

How a LED display is designed
Method of displaying characters on 7-segment displays
Displays with a greater number of segments
Microcontrollers for controlling displays

In this article, we will discuss 7-segment LED displays in detail, take a look at their design, applications, method of control and significance in the modern world of electronics. From simple indicators to advanced devices, these small but versatile components play a critical role in our lives, helping us to understand and interpret information generated by devices in digital form. Get ready for a journey into the world of LED displays, and discover how they affect our everyday lives and develop along with technological progress.

7-segment displays in TME’s offer

Design and operation of LED displays

7-segment LED displays are an inseparable component of many electronic devices and ensure readable display of numbers, letter and alphanumeric characters. Their design is relatively simple, which makes them extraordinarily effective and reliable. 7-segment displays are based (as per their name) on seven segments, which are actually LEDs of a specific shape and color. Each of these segments is typically designated by a letter from “a” to “g”. These segments are arranged to form the shape of the number 8, with three horizontal segments (top, center and bottom) and four vertical segments forming the sides. A segment designated “dp” can typically also be found on the display and is interpreted as a period or comma.

Each “segmented” LED display is made up of a greater or lesser amount of semi-conductor components, which emit light as a result of electrical current flowing through them. Segments are made from light-scattering material (primarily milky in color) in order to ensure uniformity of illumination. These diodes are connected in two ways – configuration with a common anode or common cathode. In displays with a common anode, all positive leads of LED segments are connected in a single point. Analogously, displays with a common cathode have a single lead for all negative lines.

The operation of 7-segment displays is rather simple and involves activation of the appropriate segments so as to form the desired characters. A controller, such as a microcontroller or integrated circuit, controls the current flowing through individual LEDs, depending on the digit or character to be displayed. For example, the display the digit “1”, segments “b” and “c” are activated, and the remaining segments remain inactive.

Thanks to their simple design and control, 7-segment displays are very popular in devices like calculators, clocks, meters, thermometers and many others that require the display of numbers of basic characters. These displays are not only effective and reliable but also perfectly visible in both well-lit rooms and in the darkness, which makes them irreplaceable in everyday electronics. TME offers displays of this type in many sizes – from miniature, used in small electronics, to enormous models used in sports stadiums. Displays can also be selected in terms of color and brightness.

Coding characters

Coding of characters on 7-segment displays is a critical aspect in the process of displaying information effectively and readably. There are various coding methods, of which the two most popular are BCD (Binary Coded Decimal) coding and hexadecimal coding . Besides this, the meaning of the dot on 7-segment displays is another important part of precise data display.

BCD coding table (https://www.electrical4u.com/bcd-to-seven-segment-decoder/)

BCD coding is one of the most commonly used methods of encoding digits on 7-segment displays. It involves assigning a unique binary code (typically 4-bit) to every digit from 0 to 9 and certain alphanumeric characters, such as the letters from A to F. Every binary code is related to a specific set of LED segments, which must be activated to display the given digit or character.

HEX coding table (https://bcisnotes.com/secondsemester/digital-systems/hexadecimal-to-seven-segment/)

Hexadecimal coding is used to display alphanumeric characters in the hexadecimal system (digits 0-9 and letters A to F). In this case, every digit or letter is assigned a unique hexadecimal code (4- or 8-bit), which corresponds to the activation of the appropriate LED segments. This coding is particularly useful in applications where data are represented in the hexadecimal system, such as microcontroller programming or devices operating in diagnostic mode.

All possible states of a 7-segment display (https://pl.wikipedia.org/wiki/Wyświetlacz_siedmiosegmentowy)

The dot on the 7-segment display plays an important role in displaying specific and accurate data, particularly in the case of a fraction. Activating the “dp” segment next to a given digit enables its display as a fractional value. For example, in order the display the number 3.14, the “dp” segment found next to “3” will be activated, although it is worth knowing that there are designs in which the dot is situated before the character. In such a case, the “dp” segment next to “1” would be activated.

Coding of characters and precise control of segments, including the dot, on 7-segment displays is critical for displaying various information and data legibly and intuitively, which makes these displays irreplaceable in many electronic applications.

More segments – more possibilities

Besides popular 7-segment displays, there are also displays with a greater number of segments, such as 8-segment, 9-segment, 14-segment, 16-segment and even 22-segment. These more advanced designs introduce new possibilities of displaying characters and are used in specific applications where greater flexibility and precision are required. We gain even greater possibilities by using LED panels allowing for the display of simple graphics.

8-segment and 9-segment displays add additional segments in comparison to the traditional 7-segment ones, making it possible to display more alphanumeric characters and special symbols. They are often applied in control panels and measuring devices, where the display of more expansive information is required. 14-segment, 16-segment and 22-segment displays are even more advanced designs that make it possible to display more complex characters, including many letters, digits and special characters. Thanks to the greater number of segments, these displays find applications in illuminated advertising, information boards, musical instruments and medical equipment, where the precise display of diverse content is critical.

Expanded displays with a greater number of illuminated segments increase capabilities of displaying more diverse and complex information, which is important in today's world, where consumers expect increasingly advanced and interactive displays. Their applications encompass fields like consumer electronics, industry, medicine, advertising and many others. Another solution providing greater capabilities is the use of 7-segment displays connected in pairs, triads or even quads. Thanks to their common housing, consecutive characters are perfectly fitted.

Controlling LED displays

Control of segmented displays is a key part of the information displaying process. There are various methods of controlling 7-segment displays, depending on the complexity of the application and precision of displayed data. The traditional solution is to control the display using digital systems/logic in BCD code. In this approach, every digit or character is controlled by the appropriate decoder. Systems of this type are combinational designs, with the character’s BCD code on the input, activating specific outputs of the system connected to the display. This is an effective method, although somewhat labor-intensive, the implementation of which is rather complicated in comparison to more modern microcontroller-based solutions.

Today, a widespread solution is to control 7-segment displays by means of microcontrollers. They offer much greater flexibility and precision in displaying data. A programmable system transmits data to the display, deciding which segments are to be activated in order to display digits, letters or special characters. This approach allows for dynamic control of the display, enabling fluid changes of displayed content. In microntroller-based systems, multiplexing technology is often applied, particularly in designs encompassing more than on 7-segment display. This involves switching between successive displays in a very rapid manner (often invisible to the human eye), so that every display is activated for a short period of time. In other words, only one of the displays is activated at a given time, while the others remain inactive. Thanks to this, the same set of microcontroller leads can be used to control the segments of all displays. This is an efficient solution that makes it possible to save processor resources.

Controlling 7-segment displays is a critical aspect of designing many electronic devices, and selection of the appropriate method depends on the needs of the application and available resources. Regardless of the chosen technology, 7-segment displays remain irreplaceable components in a multitude of fields in the world of technology.

Transfer Multisort Elektronik (TME) is one of the world’s largest global distributors of electronic components, electrotechnical parts, workshop equipment, and industrial automation. The catalog includes over 1,500,000 products from 1,300 leading manufacturers. TME’s modern logistics centers in Łódź and Rzgów (Poland), with a combined area of over 40,000 m², ship nearly 6,000 packages daily to customers in more than 150 countries.

TME also invests in the development of knowledge and skills of young engineers and electronics enthusiasts through the TME Education project, and supports the tech community by organizing the TechMasterEvent series, promoting innovation and experience exchange.