Interface PIR With AVR


Passive Infrared Sensor which uses the IR to detect the motion. It detects an object that has moved in or out of the sensor range.

  • PIR is basically made up of a pyroelectric sensor.
  • The round metal with a rectangular crystal in the center, which can detect the level of infrared radiation.
  • The sensor in a motion detector is actually split into two halves.
  • When the sensor is idle, both slots detect the same amount of IR.
  • When motion detected it first intercepts one half of the PIR sensor.
  • When the warm body leaves the sensing area, the reverse happens, whereby the sensor generates a negative differential change.
  • The PIR detects motion, the output pin will go “high” to 3.3V.

Hardware Required

  • PIR Sensor.
  • Atmega16 MicroController.


  • Vcc: +5v.
  • OutPut: 3.3v.
  • Gnd: Gnd.