GPIO and Python (9/9) - PIR

By The Pi HutOct 21, 20130 comments

In this project you will learn how to wire and program a passive infrared sensor.

Things you will need:

Raspberry Pi + SD Card
Keyboard + Mouse
Monitor + HDMI Cable
Power Supply
Breadboard
1x Red LED
1x Blue LED
2x 330? Resistor
5x M/M Jumper Wire
12x M/F Jumper Wire
1x Button
1x Buzzer
1x DS18B20 Temperature Sensor
1x 4k7? Resistor
1x 1uF Capacitor
1x Light Dependent Resistor (LDR)
1x PIR Sensor

Prerequisites:

Latest version of Rasbian installed on your SD Card
Raspberry Pi setup with a keyboard, mouse and monitor

1. Change the current directory to our gpio_python_code directory:

cd gpio_python_code

2. Start by creating a file for our pir script

touch 9_pir.py

3. Edit the 9_pir.py script using nano 9_pir.py add the following code:

#!/usr/bin/python



import RPi.GPIO as GPIO

from time import sleep



GPIO.setmode(GPIO.BCM)

GPIO.setup(27,GPIO.OUT)



GPIO_PIR = 7



print "PIR Module Test (CTRL-C to exit)"



# Set pin as input

GPIO.setup(GPIO_PIR,GPIO.IN)



Current_State  = 0

Previous_State = 0



try:

    print "Waiting for PIR to settle ..."

    # Loop until PIR output is 0

    while GPIO.input(GPIO_PIR)==1:

        Current_State  = 0 

    print "  Ready" 

    # Loop until users quits with CTRL-C

    while True :

        # Read PIR state

        Current_State = GPIO.input(GPIO_PIR)

        if Current_State==1 and Previous_State==0:

            # PIR is triggered

            print "  Motion detected!"

            # Record previous state

            GPIO.output(27,GPIO.HIGH)

            sleep(1)

            GPIO.output(27,GPIO.LOW)

            Previous_State=1

        elif Current_State==0 and Previous_State==1:

            # PIR has returned to ready state

            print "  Ready"

            Previous_State=0

        # Wait for 10 milliseconds

        sleep(0.01)



# clean up gpio pins when we exit the script

except KeyboardInterrupt:

    print "  Quit" 

    # Reset GPIO settings

    GPIO.cleanup()