Interfacing of electronic switch with 8051



  • What is electronics switch? – A switch is an electrical component that can break an electrical circuit, interrupting the current or diverting it from one conductor to another. There are two main state of switch “open” and “close”. And each switch has a mechanism that is “toggle” or “momentary”. Toggle mean flip switch for continuous  “on”  or  “off”. Momentary mean push-for “on” or push-for “off”.

Rocker elcetronic Switch

  • Types of electronic switch
Type Type expansion Description Symbol
SPST Single pole single throw A simple on-off switch: The two terminals are either connected together or disconnected from each other. An example is a light switch  SPST electronic Switch
SPDT Single pole double throw A simple changeover switch: C (COM, Common) is connected to L1 or to L2.  SPDT electronic  Switch
SPTT or SPCO Single pole triple throw or single pole change over Similar to SPDT. Some suppliers use SPCO/SPTT for switches with a stable off position in the centre and SPDT for those without  SPDT elctronic Switch
DPST Double pole single throw Equivalent to two SPST switches controlled by a single mechanism  DPST electronic switch
DPDT double pole double throw Equivalent to two SPDT switches controlled by a single mechanism.  DPDT electronic switch
DPCO Double pole changeover Schematically equivalent to DPDT. Some suppliers use DPCO for switches with a stable center position and DPDT for those without. A DPDT/DPCO switch with a center position can be “off” in the center, not connected to either L1 or L2, or “on”, connected to both L1 and L2 at the same time. The positions of such switches are commonly referenced as “on-off-on” and “on-on-on” respectively.  DPDT electronic switch
2P6T two pole six throw Changeover switch with a (COM, Common) which can connect to L1, L2, L3, L4, L5, or L6; with a second switch (2P, two pole) controlled by a single mechanism  Diagram_of_2P6T_switch
INTERMEDIATE SWITCH Intermediate switch DPDT switch internally wired for polarity-reversal applications: only four rather than six wires are brought outside the switch housing.  Crossover electronic switch

connection of electronic switch with 8051   different type of electronic switch

  • Operation – We can interface a switch to microcontroller by two way as shown in above image.
  1. 1.   Connecting switch by Vcc and MCU (SW1) – detecting switch by logic ‘1’ at port pin when switch is pressed (here pin 0 of port 0).
  2. 2.   Connecting switch by GND and MCU (SW2) – detecting switch by logic ‘0’ at port pin when switch is pressed (here pin 1 of port 0).
  • Applications- Different types of switches are used according to different parameters. Like computer keyboard and mobile keypad are use momentary SPST switches. Home Appliances use SPDT switches.

1. Circuit diagram of two electronic switch ,8 led and seven segment connected with 8051

electronic switch with 7 segment and led

1. Program of  Control Led Blinking Using  electronic  Switch  With 8051 


PROTEUS File for SIMULATION(Password Of RAR file is

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2. Program of  Two ELECTRONIC SWITCH  one for LED other for 7 SEGMENT  With 8051


PROTEUS File for SIMULATION(Password Of RAR file is

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