Home Automation¶

Description¶

Home automation is a big part of “The Internet of Things”… Nowadays, all of our devices and appliances are connected to provide us with a seamless control over all aspects of our home and more. With home automation, you decide how a device should react, when it should react, and why it should react. You can automate tasks such as opening and closing a gate based off of your personal preferences thus providing convenience, control, money savings, and an overall smarter home. All of this can be easily achieved with the help of a single Raspberry Pi.

Learning Objectives¶

Coding, electronics, and physical science through a hands-on application that can be directly related to real life situations.

Motion detection using ultrasonic sensors

The use of frequency, period and duty cycle of a signal to control the movement of a servo motor

IoT: How devices communicate with each other in real life applications

The implementation of the engineering design process

Application of theoretical concepts to real life situations

Materials Needed¶

Raspberry Pi with micro SD card and Raspbian

Breadboard

Jumper wires

Ultrasonic Sensor: HC-SR04

Servo Motor

LED lights

4x 1.5V Batteries + Casing

Glue gun and glue sticks

Cutter blades or scissors

Thin sturdy foam board (optional: used for the home design)

Setup and Functionality¶

For our home automation project, we want to automate a few things around the house. Let’s start with the gate! When someone arrives at the gate, the ultrasonic sensor detects that someone is close. Then, the gate opens and the garden lights turn on. Few seconds later, the gate closes and the main door opens and the house lights up.

Circuitry and Electronics:¶

LED lights: we have 2 sets of led lights

6 LED lights in the garden connected to GPIO pin 13

2 LED lights inside home connected to GPIO pin 12

Ultrasonic sensor: we 4 wires to connect to the RPi

VCC -> 5V

Trig -> Pin 10

Echo -> Pin 8

GND -> GND

Servo Motors: Every motor has 3 wires

First motor:

Red wire -> (+) Battery

Brown wire -> (-) Battery

Orange/yellow wire -> Pin 11

Second motor:

Red wire -> (+) Battery

Brown wire -> (-) Battery

Orange/yellow wire -> Pin 16

Note

Only 2 out of the 8 LEDs are shown in the figure.
Only 1 servo motor is shown
The other servo is connected similarly but to pin 16

Programming¶

# import the needed libraries 
import RPi.GPIO as GPIO
import time

# setup all GPIO pins
GPIO.setwarnings(False)
GPIO.setmode(GPIO.BOARD)
GPIO.setup(12,GPIO.OUT)
GPIO.setup(13,GPIO.OUT)
GPIO.setup(11,GPIO.OUT)
GPIO.setup(16,GPIO.OUT)
GPIO.setup(8,GPIO.IN)
GPIO.setup(10,GPIO.OUT)

# we initiate the servo motors with pin 7
pwm1=GPIO.PWM(11,50)
pwm2=GPIO.PWM(16,50)

# define a function to control the ultrasonic sensor 
# that returns the distance
def reading():      
    GPIO.output(10,False)
    time.sleep(0.3)
    GPIO.output(10,True)
    time.sleep(0.001)
    GPIO.output(10,False)

    while GPIO.input(8)==0:
        signalOff=time.time()

    while GPIO.input(8)==1:
        signalOn=time.time()

    timePassed=signalOn-signalOff
    distance=timePassed*17000

    return distance
    GPIO.cleanup()
while True:
    distance=reading()  # get the distance from the ultrasonic sensor
    print distance
    if distance<10:     # if the distance is less than 10
        GPIO.output(13,True)    # turn the garden light on (led light)
        pwm2.start(7.5)         # open the gate (servo motor)
        time.sleep(10)          # wait for 10 seconds
        pwm2.ChangeDutyCycle(22.5)  # close the gate (servo motor) 
        time.sleep(0.1)
        pwm2.stop()             # stop the gate servo motor
        time.sleep(1)
        pwm1.start(7.5)         # open the front door (servo motor)
        GPIO.output(12,True)    # turn on the house lights (led lights)
        time.sleep(5)           # wait for 5 seconds
        pwm1.ChangeDutyCycle(12.5)  # close the front foor (servo motor)
        time.sleep(1)   
        pwm1.stop()             # stop the front door servo motor
        GPIO.output(12,False)   # turn off all the led lights
        GPIO.output(13,False)
GPIO.cleanup()                  # reset all the GPIO pins

Science Concepts and Skills¶

Flex your brain! Did you ever consider the security of the house members? This home automation project does not deal with security. Anyone can enter this house! How can you make it more secure?