Control 7 segment LED displays with AVR

LED displays are nothing more than sets of Light Emitting Diodes. The difference is that they have different shapes to display specific information. So driving LED displays is the same as regular LEDs.

This is a simple connection when there are enough microcontroller Pins. But if you want to connect more displays, you will need more microcontroller pins than it can give you. Then it would help if you made a more advanced circuit with dynamic control.

The idea of this circuit is straightforward. The human eye is inertial and can’t notice a fast flicker of images. Thus you need to light only one display at one time and then switch to another and so on. Refreshing displays like 10 – 15 times a second should be enough to see all digits’ clear image.


  1. j.sudheer sastry

    Respected sir,

    I have seen your program written for 4 digit 7 segment led display, on 30th may 2006

    If you can do me a favour please send me how to program a 7 segment 8 digit led display using keil cross compiler in c
    Thanking you sir,
    yours sincerely
    J.sudheer sastry

  2. You have ARM 7 LPC2000 series microcontroller in your mind? If so, then it shouldnt be a problem.

  3. Ivan Christian


    nice job! By the way I have some suggestion to improve it.

    I once made my own 7 segment display for AVR. The display consist of 4 digits of seven segment which is drived by AVR in multiplexing way. It is just pretty much the same as you did, except I use 2-to-4 decoder/multiplexer (74HC139) to select which digit is drived at one time. By doing this with the same pin accounts I could drive more 7 segments digits. For instance, for 2 pins I could drive 4 digits rather than 2.

    If you are interested in it, I could send my schematic and othe documents to you (813KB zip file). just drop me a line at

    Keep up the good work!


  4. Good point. Id’ like to see your design.

  5. i want to drive 32 seven segment by one atmega 8535. how can i do it?

  6. Well I see one solution to use 5 to 32 decoder like this
    Schematic of decoder

    So you only need 5 lines of microcontroller to select one of 32 displays and 7 lines for driving each segment of seven segment display.
    I hope you get the point.

  7. I want to drive 143 seven segment LED by Pic18F425 Micro controller.
    HOw can I do it?

  8. I want to use remote control Keyboard to control My Sevent Segment LED display matrix by using ARM 7 LPC2000 , How can I do it?

  9. if there is no enough i/o pins for LPC2000 MCU use line decoder for LED matrix display and/or for keyboard matrix from remote control. This is wide question. Ask something more concrete that I could really help you 😉

  10. i am traing to drive 7 segment by Attiny 3213 by using c compiler and i need the c sours code for it pleas

  11. I am trying to find info to build a 2 digit display. I want to use it to make a Scoreboard – so click to increase number or click to reset – could you direct me to the right place

  12. I am trying to create a 3 digit display using 7 segment display. this circuit is a scoreboard that has 5 buttons that can allow you to “add” and “subtract” and also allow you to “set” and “reset”, and “clear” the score. will you help me for the design the circuit?

  13. how to burn the code into atmega? can u pl send the avr code to interface one 7 segment led with atmega 16…

  14. how to burn code into atmega? can u pls send the avr code for interfacing one 7 sement led with atmega16?

  15. can u pls send the avr code for interfacing one 7sement led with atmega16???

  16. I am looking for a circuit to drive three 7 segment LED display from a remote position. The display will be able to show any number from 000 to 999

  17. I am looking for a circuit to drive three 7 segment LED display from a remote position. The display will be able to show any number from 000 to 999. Does any body have a clue from where I can get this circuit?

  18. if im using microprocessor 68k. how is the connection for d 7 segment?? is it the same way??
    cos im try to build a basketball score board. is there any reference?

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