Car Anti theft System Project using Microcontroller PIC16f73

For a while we have been sharing many electronic projects for engineering students and then we found out there was a huge demand for embedded projects, especially PIC microcontroller based projects. After a short break, here is another outstanding one that is not only suitable for electronics engineering but mechanical engineering students too.Car Anti theft System Project using Microcontroller PIC16f73  schematich

Now coming to the project topic, as seen from the title it’s related to security systems which is of main concern these days.

This vehicle anti theft system will lock the wheel when it rotates more than preset cycles whenever the key is in OFF condition. The main component of the circuit is PIC16F73; it’s compatible for PIC16F877A also but I have used PIC16F73 as it’s comparatively small (28 pin). It uses an IR sensor system to detect rotation of the wheel.

Circuit diagram of anti theft system for cars

Components Required

  1. PIC 16F73
  2. Transistor BC 548 X 2
  3. Zener diode
  4. Photodiode
  5. IR Led
  6. Capacitors (33pFx2;10uF)
  7. Resistors (1k x5; 330 ohmX2)
  8. Buzzer


  • An IR LED and photo diode pair is used to detect rotation of the wheel. It’s attached with a disk which has openings; IR rays will pass through these openings.
  • When the wheel is rotating, IR rays will be cut by the disk openings which will make a pulse output on the photo diode.
  • Output of photo diode is connected to external clock input pin of TIMER0/COUNTER0 of the PIC.
  • Pulses from the photo diode are counted by the counter. Each time the counter value is compared against the pre-set value and it will set the RC1 (1st pin PORTC).Car Anti theft System Project using Microcontroller PIC16f73
  • The relay used to control the locking device is connected at RC1. RC0 is used to check the key condition, locking is done only when the key is under OFF condition.
  • The input from key can be +12V, it is regulated by a 5.1V zener diode connected in the circuit as PIC can’t connect +12V.
  • RC2 is used to indicate that the system is working; here we connect a green LED which will start blinking when the system is ready.
  • RC3 is used to connect an LED to indicate that the locking device is ON or OFF; it will set when locking occurs.
  • RC4 is used to connect a buzzer to indicate that the preset rotation cycle has reached and system is going to lock the wheel, it will be ON for 1 second and after that it will reset.
  • I have used HITECH C compiler to compile the program. Crystal frequency used is 20 Mhz.



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About The Author

Ibrar Ayyub

I am an experienced technical writer with a Master's degree in computer science from BZU Multan University. I have written for various industries, mainly home automation, and engineering. I have a clear and simple writing style and am skilled in using infographics and diagrams. I am a great researcher and is able to present information in a well-organized and logical manner.

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