Simple PIR sensor program for raspberry Pi.

pir_sensor.py

import RPi.GPIO as GPIO
import datetime
import time
GPIO.setmode(GPIO.BCM)
GPIO_PIR = 21
GPIO.setup(GPIO_PIR,GPIO.IN)
Current_State = 0
Previous_State = 0
try:
    print "Waiting for PIR to settle ..."
    while GPIO.input(GPIO_PIR)==1:
        Current_State = 0
    print " Ready "
    while True :
        Current_State = GPIO.input(GPIO_PIR)
        if Current_State==1 and Previous_State==0:
            print " Motion detected!"
            print datetime.datetime.now()
            Previous_State=1
        elif Current_State==0 and Previous_State==1:
            print " Ready"
            Previous_State=0
        time.sleep(0.01)
except KeyboardInterrupt:
    print " Quit"
    GPIO.cleanup()