Got up and saw that the Ac is off , but you set it to 19 degrees. This is what a smart system is , when the sensors inside the Ac found out that the threshold for the room temperature is crossed it automatically stops . Now lets say I have connected tube light with it and whenever temperature crosses some threshold the tubelight goes off. Now this is called connecting devices, sensors and appliances so that they exchange data with each other and when you add one more thing that is: over a network then its called as IOT. IOT is a network of Internet connected devices able to collect and exchange data . Iot platform is basically when some sensor collects some data ,and send it to cloud, then the software performs some task and give output to the connected devices.
Now after collection of data by the sensor one way is that we can upload that data to the cloud and then any other device connected to that cloud can see it and interpret the results. One such cloud platform us ThingSpeak. The other way we need to think about is how this exchange of data takes place between device in a network. This network include Wifi, Bluetooth, Zigbee , MQTT, cellular etc.These are also called Iot protocols.
Lets say you have connected a microcontroller with a Bluetooth enabled chip , now you connect your phone with that bluetooth network , then your phone and microcontroller can interact with each other over small range .Now you can connect any sensor or device with microcontroller and they can easily interact with our phone . There are various apps that provides wearable technology to get easily connected to smart gadgets. Smart glass can be easily made with Bluetooth technology ,using Arduino and OLED. The only problem with Bluetooth is that Bluetooth does not allow large file to exchange but only allows small portion of data.
Moving on to wifi which is standard 802.11 ,can transfer hundreds of megabits in only one second. Now days there are many microcontrollers available that have inbuilt wifi In it , but there is also a wifi chip available which can be connected to a device . Then all the devices connecting that network can exchange data among themselves. It has quick data transfer rates but the only own drawback of this IoT protocol is it can consume excessive power for some of the IoT Application. Its range is 50m , We can easily built a home automation system with wifi ,all the devices, sensors will be connected , it would include temperature monitoring , automatic lights on off , fan switching on during hot conditions and vice versa, ac monitoring , smart bed etc.
ZIGBEE which is not known to most of the people because it is mostly designed for industries not customers. It operates at a frequency of 2.4GHz. In industries and chemical plants and others large amount of Zigbee modules are connected with each other to exchange and monitor data, forming a network of Zigbee devices . One Zigbee connects easily with other using I/O line passing.At small scale ,there are Xbee modules available in market , with which we can built an automated device , like we can switch any lights off or on from any other room using two xbee modules , one with us and other attached to light. The two modules will transfer and receive signals using I/o line passing (same data on same data pin of two modules).
Fourth is MQTT, Message Queue Telemetry Transport ,as the name suggests is an message protocol. This protocol usually runs over TCP/IP. It used for monitoring from a remote area in IoT. MQTT can obtain data from so many electrical devices.This MQTT protocol is made of three core mechanisms: Subscriber, Publisher, and Broker. The publisher generates and transmits the data to the subscriber with the help of the broker. The broker, ensures security by checking and rechecking the authorization of the subscribers and the publishers.So basically there is the broker and lot of MQTT clients so this broker acts as a post office , whenever some client want to publish anything i.e want to share or get any information then the clients subscribes to it or connected to it can see the message . In case of a broker failure there is a backup broker to manage the clients . Basically a broker is a software running on a system or cloud just like a server ,and clients are just devices/ microcontrollers which has a MQTT library .MQTT protocol provides information routing functions to the cheap, low-memory power consuming , small or mini devices with the help of low and vulnerable bandwidth based network.
Shristi uniyal 