7 Segment Display

How to tell if you have a common anode or a common cathode 7 segment display?

by Kalpasjack
January 02, 2020

As far as I know all 7 segment displays are able to work both in a common anode and a common cathode mode.

With a 7 segment display you have 8 control pins (1 for each segment + 1 for the dot) and 2 power pins (Vcc and GND). Usually these are pins 3 and 8 (so the middle bottom and middle top ones), not necessarily in that order.

You don't connect both of these power pins, only one based on if you want common anode or common cathode. With common anode you're applying a common voltage to Vcc (usually +5 volts in series to a 510 ohm - 1 kiloohm resistor), while the pins of the segments you want to light up are connected to the ground.

With common cathode mode you connect the GND pin to ground and bring positive voltage to the pins of the segments you want to light up .

Hope this helps.

by miminyte
January 03, 2020

Yes it helps and I Thank you very much.

by Kalpasjack
January 03, 2020

1 Answer

Answer by jaksonlee

seven segment displayā€¯, consists of seven LEDs (hence its name) arranged in a rectangular fashion as shown. 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 within the same package thus allowing the indication of a decimal point, (DP) when two or more 7-segment displays are connected together to display numbers greater than ten.

Each one of the seven LEDs in the display is given a positional segment with one of its connection pins being brought straight out of the rectangular plastic package. These individually LED pins are labelled from a through to g representing each individual LED. The other LED pins are connected together and wired to form a common pin.

+2 votes
by jaksonlee
January 28, 2020

Your Answer

You must log in or create an account (free!) to answer a question.

Log in Create an account

Go Ad-Free. Activate your CircuitLab membership. No more ads. Save unlimited circuits. Run unlimited simulations.

Search Questions & Answers

Ask a Question

Anyone can ask a question.

Did you already search (see above) to see if a similar question has already been answered? If you can't find the answer, you may ask a question.

About This Site

CircuitLab's Q&A site is a FREE questions and answers forum for electronics and electrical engineering students, hobbyists, and professionals.

We encourage you to use our built-in schematic & simulation software to add more detail to your questions and answers.

Acceptable Questions:

  • Concept or theory questions
  • Practical engineering questions
  • “Homework” questions
  • Software/hardware intersection
  • Best practices
  • Design choices & component selection
  • Troubleshooting

Unacceptable Questions:

  • Non-English language content
  • Non-question discussion
  • Non-electronics questions
  • Vendor-specific topics
  • Pure software questions
  • CircuitLab software support

Please respect that there are both seasoned experts and total newbies here: please be nice, be constructive, and be specific!

About CircuitLab

CircuitLab is an in-browser schematic capture and circuit simulation software tool to help you rapidly design and analyze analog and digital electronics systems.