This document discusses seven segment displays and how to interface them with microcontrollers. A seven segment display uses 7 LED segments (a, b, c, d, e, f, g) plus a decimal point to display numbers from 0 to 9. There are two types: common cathode, where the cathodes are connected and the anodes are individual; and common anode, where the anodes are connected and the cathodes are individual. When interfacing with a microcontroller like the 8051, common cathode displays use logic high outputs while common anode uses logic low outputs to light the correct segments to display the desired number.

1. What is seven segment display?
How it works?
Seven segment display handling with 8051
microcontroller.

3.  Seven segment display comprises seven
LEDs and a LED for decimal point.
 Lit them in order ,can forms different
letters and alphabets.
 Seven segment display is special for
displaying numerical characters.

4. Displaying 0-9 in SSD

6.  Each segment is designated as a, b, c, d, e, f
and g along with dp for decimal point.

7.  There are two types of seven segment
display.
• Common cathode seven segment display.
• Common anode seven segment display.

8.  Common cathode

9.  Common cathode seven segment display is
such in which cathode of each LED is
connected to make single pin while anode
are separate.
 In order to lit required LED high voltage is
supplied to anode.
 They are interfaced with logic high.
 A required value of resistance is to be
connected across anode in order to prevent
their fusion.

10. Common anode

11.  In Common anode seven segment display
anode of each LED is connected to make a
single pin.
 In order to lit LED ,cathode of each LED is to
be connected individually with logic 0 i.e.
with low voltage.
 Anode is supplied with required regulated lit
voltage.

13.  During interfacing seven segment display
with μc 8051,both types of seven segment
display can be interfaced.
 For common cathode SSD logic 0-output is to
be considered.
 For common anode SSD logic 1-output is to
be considered.

14.  In system with input , program should be
done conditionally.
 By using conditional statements we can
display letters and alphabet in SSD.