Stepping towards IoT - Basic Application to integrate MS Azure Web API with GIPO Bread Board Circuit through Raspberry Pi

There is a new jargon in the IT world called IoT - Internet of things. This is not new to IT industry but it is not that common. This blog is not to cover about IoT or any other technologies in details. Rather, I have tried to provide technical information on how to collaborate different technologies and create an end to end basic IoT application.

For this IoT application development, I have used the following technologies / hardware:

Technologies

1.      MS Azure Cloud Service

2.      Python

Hardware 

1.      Raspberry Pi 2

2.      GIPO Bread Board to create circuit

3.      1K Ohm 1/4 W 0.25W Resistor

4.      Two LEDs - Red and Green

5.      One Wire

6.      RPi GPIO T-Cobbler

7.      8" 40 Pin Ribbon Cable for Raspberry Pi 2

Let us start with the creation of some code before we go to the circuit designing.

MS Azure Cloud Service

We would be creating a very basic Cloud service to activate a circuit. You can also create the service locally and test it, but objective here is to call Web API service from Cloud and enable the circuit. Also, the purpose of creating a web service and hosting it at some other server is to create a service or the source of data which can be called from any platform or hardware. 

Create a simple Web API service method which will return the value as true when the system service is called from any client application.

IoTMessageController exposes a simple get method which returns bool value.

This example is nothing more than "Hello World" application where we try to test the first hand technology or integration.

 Once this Web API is created, you can host it to the MS Azure Cloud. We'll be creating a Python program to call the Web API Service later in this blog.

Circuit Design

 

You can see the T-Cobbler is numbered with some codes. It is very important to understand the codes and do not disorders with wrong connection as it might burn the circuit due to wrong connection with the power pins.

Let us assemble the circuit as per below -

1. Attach T-Cobbler to GIPO bread board. Make sure pins are properly fitted into the board
2. Fix the 8" 40 pin Ribbon Cable to T-Cobbler
3. G23 ( with anode of Resistor)->28 (with cathode of Resistor)
4. G18 ( with anode of Resistor)->26 (with cathode of Resistor)
5. Connect Black Wire from GND -> -ve section hole. As shown in the figure
6. Now we are having two LEDs.
7. Connect Green -> anode of LED at 26 hole -> cathod to -ve section hole
8. Connect Red -> cathode of LED at 28 hole -> cathode to -ve section hole

Connecting to Raspberry Pi2

 Connect another section of Ribbon Cable to the Raspberry Pi 2 pins, as shown in the above figure.

Python Code

The purpose of writing a code in python is to call service and trigger GIPO circuit board. Python is easily available in all the platforms. Since we are using Raspberry Pi Mother board and we have the operating system which is Linux based, therefore, it become obvious choice to use Python. You can use other languages as well like C++ to call to the service and read board.

#!/usr/bin/env python2
import urllib2
import urllib
import time
import RPi.GPIO as GPIO

DEBUG = True

GPIO.setwarnings(False)

GPIO.setmode(GPIO.BCM)

GREEN_LED = 18
RED_LED = 23

GPIO.setup(GREEN_LED, GPIO.OUT)
GPIO.setup(RED_LED, GPIO.OUT)

if DEBUG:
  print('Calling Azure Web API')
  url='http://366bfa6fd6bd44d4846a1a3d44abe2b7.cloudapp.net/api/IoTMeassage'
  data = urllib2.urlopen(url)
  info = data.read()
  if (info == 'true'):
                   GPIO.output(GREEN_LED, True)
                   GPIO.output(RED_LED, False)
  else:
                   GPIO.output(RED_LED, True)
                   GPIO.output(GREEN_LED, False)
time.sleep(20)

GPIO.cleanup()

Execute python program to enable the circuit

Open the terminal in the Raspberry Pi OS and execute the program by the commands mentioned in the screen.

When the service is called, the value is checked for true. In case the value matches with the condition the Green LED will trigger otherwise Red LED will trigger. I have added the timer sleep setting as 20 sec which will make the light glow for 20 seconds before cleaning the GPIO circuit board. You can extend your circuit to do 'N' number of stuff or you can connect it to any other available circuit boards available in the market to communicate with the application on the cloud.

 Summary

You have read above about how basic program can be used to trigger GIPO bread board. Now, you can create your own applications, programs and design circuits to innovate your ideas. IoT is the next big thing if we understand the power of collaboration. You can use IoT for automation or get the information from the circuit/device and load it to your cloud system for the analysis. There is no limit to the imagination with IoT.