1. Display Devices
7 segment led display

2. What is 7-segment LED Display?
7-segment LED Display is display device which can display one digit at a time
Actually one digit is represented by arrangement of 7 LEDs in a small cubical box
For representing 3 digit number we need three
7-segment LED Displays

3. How it look like?

4. Internal Structure There are two types of 7-segment LED Display
Common Cathode
Common Anode

5. Common Cathode

6. How to glow the segments?
We need to provide +5 V to other open ends to turn ON that particular segments
We need to provide 0 V to other open ends to turn OFF that particular segments

7. How to print 2 on LED Display?
To show 2 on LED display then you must illuminate A, B, G, E and D segments of the display. So you must give voltages on pins 10, 9, 8, 5, 4, 2, 3 and 7 in Common cathode slide as High, High, Low, High, High, Low, High and Low respectively for drawing 2 on display

8. Common Anode

9. How to glow the segments?
We need to provide +5 V to other open ends to turn OFF that particular segments
We need to provide 0 V to other open ends to turn ON that particular segments

10. How to print 3 on LED Display?
To make 3 on display then you must illuminate A, B, C, D and G segments of the display. So you must give voltages on pins 10, 9, 8, 5, 4, 2, 3 and 7 in figure 4 as High, High, High, High, Low, Low, High and Low respectively for drawing 3 on display

11. BCD to 7 segments Decoder

12. Inputs and Outputs of BCD to 7 segment decoder

13. Pin Out of Common Anode LED Display

14. Interfacing with ATmega8

15. Multi Digit 7 segments LED Display (Multiplexing)

16. Circuit diagram for multiplexing

17. Thank You!!!