Implementation of IoT with Raspberry Pi

IoT

Internet of Things

• Creating an interactive environment
• Network of devices connected together

Sensor

• Electronic element
• Converts physical quantity into electrical signals
• Can be analog or digital

Actuator

• Mechanical/Electro-mechanical device
• Converts energy into motion
• Mainly used to provide controlled motion to other components

System Overview

• Sensor and actuator interfaced with Raspberry Pi
• Read data from the sensor
• Control the actuator according to the reading from the sensor
• Connect the actuator to a device

Requirements

• DHT Sensor
• 4.7K ohm resistor
• Relay
• Jumper wires
• Raspberry Pi
• Mini fan

DHT Sensor

• Digital Humidity and Temperature Sensor (DHT)
• PIN 1,2,3,4 (from left to right)
• PIN 1-3.3V - 5V Power supply
• PIN 2- Data
• PIN 3- Null
• PIN 4 - Ground

Relay

Mechanical/electromechanical switch

3 output terminals (left to right)

• NO (normal open) :
• Common
• NC (normal close)

Temperature Dependent Auto Cooling System

Sensor interface with Raspberry Pi

• Connct pin 1 of DHT sensor to the 3.3V pin of Raspberry Pi
• Connect pin 2 of DHT sensor to any input pins of Raspberry Pi, here we have used pin 7
• Connect pin 4 of DHT sensor to the ground pin of the Raspberry Pi

Relay interface with Raspberry Pi

• Connect the VCC pin of relay to the 5V supply pin of Raspberry Pi
• Connect the GND (ground) pin of relay to the ground pin of Raspberry Pi
• Connect the input/signal pin of Relay to the assigned output pin of Raspberry Pi (Here we have used pin 11)

Adafruit provides a library to work with the DHT22 sensor

Install the library in your Pi -

• Get the clone from GIT

          → git clone https://github.com/adafruit/Adafruit_Pythone_DHT.git

• Go to folder Adafruit_Python_DHT

          → cd Adafruit_Python_DHT

• Install the library

          → sudo python setup.py install

Program : DHT22 with Pi

 Output :

Connection : Relay

• Connect the relay pins with the Raspberry Pi as mentioned in previous slides 
• Set the GPIO pin connected with the relay's input pin as output in the sketch

               GPIO.setup (11,GPIO.OUT)

• Set the relay pin high when the temperature is greater than 30

                  if temperature > 20:

                     print ('Temp > 20')

                   GPIO.output (FAN,0)

                    print('Fan on')

                     sleep(5)

                     print('Fan off ')

                    GPIO.output(FAN,1)

else:

                  GPIO.output(FAN,1)

                  print ('Temp below max value.FAN OFF')

Connection : Fan

Connect the Li-po battery in series with the fan

• No terminal of the relay -> positive terminal of the Fan.
• Common terminal of the relay -> Positive terminal of the battery
• Negative terminal of the battery -> Negative terminal of the fan.

Run the existing code. The fan should operate when the surrounding temperature is greater than the threshold value in the sketch