IOT Subject NOTES
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Connecting everyday things embedded with electronics, software, and sensors to internet enabling to collect and exchange data without human interaction called as the Internet of Things (IoT).
The term "Things" in the Internet of Things refers to anything and everything in day to day life which is accessed or connected through the internet.
IoT is an advanced automation and analytics system which deals with artificial intelligence, sensor, networking, electronic, cloud messaging etc. to deliver complete systems for the product or services. The system created by IoT has greater transparency, control, and performance.
As we have a platform such as a cloud that contains all the data through which we connect all the things around us. For example, a house, where we can connect our home appliances such as air conditioner, light, etc. through each other and all these things are managed at the same platform. Since we have a platform, we can connect our car, track its fuel meter, speed level, and also track the location of the car.
As we have a platform such as a cloud that contains all the data through which we connect all the things around us. For example, a house, where we can connect our home appliances such as air conditioner, light, etc. through each other and all these things are managed at the same platform. Since we have a platform, we can connect our car, track its fuel meter, speed level, and also track the location of the car.
If there is a common platform where all these things can connect to each other would be great because based on my preference, I can set the room temperature. For example, if I love the room temperature to to be set at 25 or 26-degree Celsius when I reach back home from my office, then according to my car location, my AC would start before 10 minutes I arrive at home. This can be done through the Internet of Things (IoT).
How does Internet of Thing (IoT) Work?
The working of IoT is different for different IoT echo system (architecture). However, the key concept of there working are similar. The entire working process of IoT starts with the device themselves, such as smartphones, digital watches, electronic appliances, which securely communicate with the IoT platform. The platforms collect and analyze the data from all multiple devices and platforms and transfer the most valuable data with applications to devices.
Features of IOT
The most important features of IoT on which it works are connectivity, analyzing, integrating, active engagement, and many more. Some of them are listed below:
Connectivity: Connectivity refers to establish a proper connection between all the things of IoT to IoT platform it may be server or cloud. After connecting the IoT devices, it needs a high speed messaging between the devices and cloud to enable reliable, secure and bi-directional communication.
Analyzing: After connecting all the relevant things, it comes to real-time analyzing the data collected and use them to build effective business intelligence. If we have a good insight into data gathered from all these things, then we call our system has a smart system.
Integrating: IoT integrating the various models to improve the user experience as well.
Artificial Intelligence: IoT makes things smart and enhances life through the use of data. For example, if we have a coffee machine whose beans have going to end, then the coffee machine itself order the coffee beans of your choice from the retailer.
Sensing: The sensor devices used in IoT technologies detect and measure any change in the environment and report on their status. IoT technology brings passive networks to active networks. Without sensors, there could not hold an effective or true IoT environment.
Active Engagement: IoT makes the connected technology, product, or services to active engagement between each other.
Endpoint Management: It is important to be the endpoint management of all the IoT system otherwise, it makes the complete failure of the system. For example, if a coffee machine itself order the coffee beans when it goes to end but what happens when it orders the beans from a retailer and we are not present at home for a few days, it leads to the failure of the IoT system. So, there must be a need for endpoint management.
Architecture of iot:
Perception/Sensing Layer
The first layer of any IoT system involves “things” or endpoint devices that serve as a conduit between the physical and the digital worlds. Perception refers to the physical layer, which includes sensors and actuators that are capable of collecting, accepting, and processing data over the network. Sensors and actuators can be connected either wirelessly or via wired connections. The architecture does not limit the scope of its components nor their location.
Network Layer
Network layers provide an overview of how data is moved throughout the application. This layer contains Data Acquiring Systems (DAS) and Internet/Network gateways. A DAS performs data aggregation and conversion functions (collecting and aggregating data from sensors, then converting analog data to digital data, etc.). It is necessary to transmit and process the data collected by the sensor devices. That’s what the network layer does. It allows these devices to connect and communicate with other servers, smart devices, and network devices. As well, it handles all data transmissions for the devices.
Processing Layer
The processing layer is the brain of the IoT ecosystem. Typically, data is analyzed, pre-processed, and stored here before being sent to the data center, where it is accessed by software applications that both monitor and manage the data as well as prepare further actions. This is where Edge IT or edge analytics enters the picture.
Application Layer
User interaction takes place at the application layer, which delivers application-specific services to the user. An example might be a smart home application where users can turn on a coffee maker by tapping a button in an app or a dashboard that shows the status of the devices in a system. There are many ways in which the Internet of Things can be deployed such as smart cities, smart homes, and smart health.
Stages of IoT Solutions Architecture
Having discussed the IoT layers, how can businesses benefit from them and how can they maximize the value of IoT? The Internet of Things (IoT) may refer to connected devices and protocols, but in reality, the data from these devices is siloed, fragmented, and isolated. As such, these fragmented insights alone do not provide enough information to justify an IoT strategy that involves a significant investment of resources. To capitalize on IoT, enterprises must allow devices to interact freely, and they must maximize device and system synergies. You need to ensure your infrastructure supports the IoT architecture. The following are various stages of IoT architecture implementation in enterprises:
Connected Objects/Devices
As a first step towards IoT architecture, the physical layer must be established within the environment. There would be no Internet of Things without “smart” or connected objects. Typically, these are wireless sensors or actuators in the perception layer.
Sensors collect and analyze data from the environment in order to make it usable for further analysis. Actuators are involved in measuring the change recorded by the sensors. It is possible to connect sensors or actuators in a wired or wireless manner in order to perform sensing and actuation. Local Area Networks (LANs) and Personal Area Networks (PANs) can be used for connecting sensors and actuators.
Internet Gateway
When step one is done properly, the next step that needs to be done is to set up an internet gateway. As the sensors and actuators collect data in analog form, we must have a means of converting the analog data into digital data in order to process it. We use the internet gateway to accomplish this task. In the internet gateway stage, raw data will be received from the devices and pre-processed before being sent to the cloud.
Data Acquisition Systems can be used to convert analog data into digital forms. It connects to the sensors and actuators and gathers all data, converting it to digital form so that it may be routed over the network by the internet gateway. It is responsible for data aggregation and conversion. We can also add additional features, such as analytics and security, to increase performance and efficiency.
Edge IT Systems
The third stage of an IoT architecture involves pre-processing and enhanced data analytics. In light of the significant amount of data collected by IoT systems and the consequent bandwidth requirements, edge IT systems play a crucial role in reducing the pressure on the core IT infrastructure. Edge IT systems employ machine learning and visualization techniques to generate insights from collected data. Machine learning algorithms provide insights into the data while visualization techniques present the data in an easy-to-understand manner.
Directly sending data to the server or the data center will cripple the speed of the system, as well as the bandwidth of the LAN or routers. Analog data is generated at an enormous speed and will require a great deal of space. Therefore, it is always recommended to convert the data into digital form. Most of the time, the data collected by sensors and actuators are not valuable to the organization, so only the important data is processed and transmitted to data centers and servers.
Data Centers and Cloud Storage
After the data has been properly preprocessed and analyzed, and all loopholes have been removed, the data is sent to the data centers and servers for final analysis and reporting. Data Centers and Cloud services fall under the Management Services category and usually process data through analytics, device management, and security controls. Furthermore, the cloud also enables the transfer of data to end-user applications like Healthcare, Retail, Environment, Emergency, Energy, etc.
Upon analysis, the data can be sent to cloud-based servers or data centers for final processing. Using the cloud platform can lower hardware costs, but securing data is also a concern. When it comes to physical servers or data centers, they are safer, but they also cost more.
Major Components of IOT:
These are explained as following below.
Things or Device
These are fitted with sensors and actuators. Sensors collect data from the environment and give to gateway where as actuators performs the action (as directed after processing of data).
Gateway
The sensors give data to Gateway and here some kind of pre-processing of data is even done. It also acts as a level of security for the network and for the transmitted data.
Cloud
The data after being collected is uploaded to cloud. Cloud in simple terms is basically a set of servers connected to internet 24*7.
Analytics
The data after being received in the cloud processing is done . Various algorithms are applied here for proper analysis of data (techniques like Machine Learning etc are even applied).
User Interface
User end application where user can monitor or control the data.
Control Unit:
A Central Processing Unit is the most important component of a computer system. A control unit is a part of the CPU. A control unit controls the operations of all parts of the computer but it does not carry out any data processing operations.
What is a Control Unit?
The Control Unit is the part of the computer’s central processing unit (CPU), which directs the operation of the processor. It was included as part of the Von Neumann Architecture by John von Neumann. It is the responsibility of the control unit to tell the computer’s memory, arithmetic/logic unit, and input and output devices how to respond to the instructions that have been sent to the processor. It fetches internal instructions of the programs from the main memory to the processor instruction register, and based on this register contents, the control unit generates a control signal that supervises the execution of these instructions. A control unit works by receiving input information which it converts into control signals, which are then sent to the central processor. The computer’s processor then tells the attached hardware what operations to perform. The functions that a control unit performs are dependent on the type of CPU because the architecture of the CPU varies from manufacturer to manufacturer.
Examples of devices that require a CU are:
Control Processing Units(CPUs)
Graphics Processing Units(GPUs)
Functions of the Control Unit
It coordinates the sequence of data movements into, out of, and between a processor’s many sub-units.
It interprets instructions.
It controls data flow inside the processor.
It receives external instructions or commands to which it converts to sequence of control signals.
It controls many execution units(i.e. ALU, data buffers and registers) contained within a CPU.
It also handles multiple tasks, such as fetching, decoding, execution handling and storing results.
Types of Control Unit
There are two types of control units:
Hardwired
Micro programmable control unit.
Hardwired Control Unit
In the Hardwired control unit, the control signals that are important for instruction execution control are generated by specially designed hardware logical circuits, in which we can not modify the signal generation method without physical change of the circuit structure. The operation code of an instruction contains the basic data for control signal generation. In the instruction decoder, the operation code is decoded. The instruction decoder constitutes a set of many decoders that decode different fields of the instruction opcode.
As a result, few output lines going out from the instruction decoder obtains active signal values. These output lines are connected to the inputs of the matrix that generates control signals for execution units of the computer. This matrix implements logical combinations of the decoded signals from the instruction opcode with the outputs from the matrix that generates signals representing consecutive control unit states and with signals coming from the outside of the processor, e.g. interrupt signals. The matrices are built in a similar way as a programmable logic arrays.
Control signals for an instruction execution have to be generated not in a single time point but during the entire time interval that corresponds to the instruction execution cycle. Following the structure of this cycle, the suitable sequence of internal states is organized in the control unit. A number of signals generated by the control signal generator matrix are sent back to inputs of the next control state generator matrix.
This matrix combines these signals with the timing signals, which are generated by the timing unit based on the rectangular patterns usually supplied by the quartz generator. When a new instruction arrives at the control unit, the control units is in the initial state of new instruction fetching. Instruction decoding allows the control unit enters the first state relating execution of the new instruction, which lasts as long as the timing signals and other input signals as flags and state information of the computer remain unaltered.
A change of any of the earlier mentioned signals stimulates the change of the control unit state. This causes that a new respective input is generated for the control signal generator matrix. When an external signal appears, (e.g. an interrupt) the control unit takes entry into a next control state that is the state concerned with the reaction to this external signal (e.g. interrupt processing).
The values of flags and state variables of the computer are used to select suitable states for the instruction execution cycle. The last states in the cycle are control states that commence fetching the next instruction of the program: sending the program counter content to the main memory address buffer register and next, reading the instruction word to the instruction register of computer. When the ongoing instruction is the stop instruction that ends program execution, the control unit enters an operating system state, in which it waits for a next user directive.
Micro Programmable control unit
The fundamental difference between these unit structures and the structure of the hardwired control unit is the existence of the control store that is used for storing words containing encoded control signals mandatory for instruction execution. In microprogrammed control units, subsequent instruction words are fetched into the instruction register in a normal way. However, the operation code of each instruction is not directly decoded to enable immediate control signal generation but it comprises the initial address of a microprogram contained in the control store.
With a single-level control store: In this, the instruction opcode from the instruction register is sent to the control store address register. Based on this address, the first microinstruction of a microprogram that interprets execution of this instruction is read to the microinstruction register. This microinstruction contains in its operation part encoded control signals, normally as few bit fields. In a set microinstruction field decoders, the fields are decoded. The microinstruction also contains the address of the next microinstruction of the given instruction microprogram and a control field used to control activities of the microinstruction address generator. The last mentioned field decides the addressing mode (addressing operation) to be applied to the address embedded in the ongoing microinstruction. In microinstructions along with conditional addressing mode, this address is refined by using the processor condition flags that represent the status of computations in the current program. The last microinstruction in the instruction of the given microprogram is the microinstruction that fetches the next instruction from the main memory to the instruction register.
With a two-level control store: In this, in a control unit with a two-level control store, besides the control memory for microinstructions, a nano-instruction memory is included. In such a control unit, microinstructions do not contain encoded control signals. The operation part of microinstructions contains the address of the word in the nano-instruction memory, which contains encoded control signals. The nano-instruction memory contains all combinations of control signals that appear in microprograms that interpret the complete instruction set of a given computer, written once in the form of nano-instructions. In this way, unnecessary storing of the same operation parts of microinstructions is avoided. In this case, microinstruction word can be much shorter than with the single level control store. It gives a much smaller size in bits of the microinstruction memory and, as a result, a much smaller size of the entire control memory. The microinstruction memory contains the control for selection of consecutive microinstructions, while those control signals are generated at the basis of nano-instructions. In nano-instructions, control signals are frequently encoded using 1 bit/ 1 signal method that eliminates decoding.
Advantages of a Well-Designed Control Unit
Efficient instruction execution: A well-designed control unit can execute instructions more efficiently by optimizing the instruction pipeline and minimizing the number of clock cycles required for each instruction.
Improved performance: A well-designed control unit can improve the performance of the CPU by increasing the clock speed, reducing the latency, and improving the throughput.
Support for complex instructions: A well-designed control unit can support complex instructions that require multiple operations, reducing the number of instructions required to execute a program.
Improved reliability: A well-designed control unit can improve the reliability of the CPU by detecting and correcting errors, such as memory errors and pipeline stalls.
Lower power consumption: A well-designed control unit can reduce power consumption by optimizing the use of resources, such as registers and memory, and reducing the number of clock cycles required for each instruction.
Better branch prediction: A well-designed control unit can improve branch prediction accuracy, reducing the number of branch mispredictions and improving performance.
Improved scalability: A well-designed control unit can improve the scalability of the CPU, allowing it to handle larger and more complex workloads.
Better support for parallelism: A well-designed control unit can better support parallelism, allowing the CPU to execute multiple instructions simultaneously and improve overall performance.
Improved security: A well-designed control unit can improve the security of the CPU by implementing security features such as address space layout randomization and data execution prevention.
Lower cost: A well-designed control unit can reduce the cost of the CPU by minimizing the number of components required and improving manufacturing efficiency.
Disadvantages of a Poorly-Designed Control Unit
Reduced performance: A poorly-designed control unit can reduce the performance of the CPU by introducing pipeline stalls, increasing the latency, and reducing the throughput.
Increased complexity: A poorly-designed control unit can increase the complexity of the CPU, making it harder to design, test, and maintain.
Higher power consumption: A poorly-designed control unit can increase power consumption by inefficiently using resources, such as registers and memory, and requiring more clock cycles for each instruction.
Reduced reliability: A poorly-designed control unit can reduce the reliability of the CPU by introducing errors, such as memory errors and pipeline stalls.
Limitations on instruction set: A poorly-designed control unit may limit the instruction set of the CPU, making it harder to execute complex instructions and limiting the functionality of the CPU.
Inefficient use of resources: A poorly-designed control unit may inefficiently use resources such as registers and memory, leading to wasted resources and reduced performance.
Limited scalability: A poorly-designed control unit may limit the scalability of the CPU, making it harder to handle larger and more complex workloads.
Poor support for parallelism: A poorly-designed control unit may limit the ability of the CPU to support parallelism, reducing the overall performance of the system.
Security vulnerabilities: A poorly-designed control unit may introduce security vulnerabilities, such as buffer overflows or code injection attacks.
Higher cost: A poorly-designed control unit may increase the cost of the CPU by requiring additional components or increasing the manufacturing complexity.
Sensors:
Generally, sensors are used in the architecture of IOT devices.
Sensors are used for sensing things and devices etc.
A device that provides a usable output in response to a specified measurement.
The sensor attains a physical parameter and converts it into a signal suitable for processing (e.g. electrical, mechanical, optical) the characteristics of any device or material to detect the presence of a particular physical quantity.
The output of the sensor is a signal which is converted to a human-readable form like changes in characteristics, changes in resistance, capacitance, impedance, etc.
IOT HARDWARE
Transducer :
A transducer converts a signal from one physical structure to another.
It converts one type of energy into another type.
It might be used as actuator in various systems.
Sensors characteristics :
Static
Dynamic
1. Static characteristics :
It is about how the output of a sensor changes in response to an input change after steady state condition.
Accuracy: Accuracy is the capability of measuring instruments to give a result close to the true value of the measured quantity. It measures errors. It is measured by absolute and relative errors. Express the correctness of the output compared to a higher prior system. Absolute error = Measured value – True value
Relative error = Measured value/True valueRange: Gives the highest and the lowest value of the physical quantity within which the sensor can actually sense. Beyond these values, there is no sense or no kind of response.
e.g. RTD for measurement of temperature has a range of -200`c to 800`c.Resolution: Resolution is an important specification for selection of sensors. The higher the resolution, better the precision. When the accretion is zero to, it is called the threshold.
Provide the smallest changes in the input that a sensor is able to sense.Precision: It is the capacity of a measuring instrument to give the same reading when repetitively measuring the same quantity under the same prescribed conditions.
It implies agreement between successive readings, NOT closeness to the true value.
It is related to the variance of a set of measurements.
It is a necessary but not sufficient condition for accuracy.Sensitivity: Sensitivity indicates the ratio of incremental change in the response of the system with respect to incremental change in input parameters. It can be found from the slope of the output characteristics curve of a sensor. It is the smallest amount of difference in quantity that will change the instrument’s reading.
Linearity: The deviation of the sensor value curve from a particularly straight line. Linearity is determined by the calibration curve. The static calibration curve plots the output amplitude versus the input amplitude under static conditions.
A curve’s slope resemblance to a straight line describes linearity.Drift: The difference in the measurement of the sensor from a specific reading when kept at that value for a long period of time.
Repeatability: The deviation between measurements in a sequence under the same conditions. The measurements have to be made under a short enough time duration so as not to allow significant long-term drift.
Dynamic Characteristics :
Properties of the systems
Zero-order system: The output shows a response to the input signal with no delay. It does not include energy-storing elements.
Ex. potentiometer measure, linear and rotary displacements.First-order system: When the output approaches its final value gradually.
Consists of an energy storage and dissipation element.Second-order system: Complex output response. The output response of the sensor oscillates before steady state.
Sensor Classification :
Passive & Active
Analog & digital
Scalar & vector
Passive Sensor –
Can not independently sense the input. Ex- Accelerometer, soil moisture, water level and temperature sensors.Active Sensor –
Independently sense the input. Example- Radar, sounder and laser altimeter sensors.Analog Sensor –
The response or output of the sensor is some continuous function of its input parameter. Ex- Temperature sensor, LDR, analog pressure sensor and analog hall effect.Digital sensor –
Response in binary nature. Design to overcome the disadvantages of analog sensors. Along with the analog sensor, it also comprises extra electronics for bit conversion. Example – Passive infrared (PIR) sensor and digital temperature sensor(DS1620).Scalar sensor –
Detects the input parameter only based on its magnitude. The answer for the sensor is a function of magnitude of some input parameter. Not affected by the direction of input parameters.
Example – temperature, gas, strain, color and smoke sensor.Vector sensor –
The response of the sensor depends on the magnitude of the direction and orientation of input parameter. Example – Accelerometer, gyroscope, magnetic field and motion detector sensors.
Types of sensors –
Electrical sensor :
Electrical proximity sensors may be contact or non contact.
Simple contact sensors operate by making the sensor and the component complete an electrical circuit.
Non- contact electrical proximity sensors rely on the electrical principles of either induction for detecting metals or capacitance for detecting non metals as well.
Light sensor:
Light sensor is also known as photo sensors and one of the important sensor.
Light dependent resistor or LDR is a simple light sensor available today.
The property of LDR is that its resistance is inversely proportional to the intensity of the ambient light i.e when the intensity of light increases, it’s resistance decreases and vise versa.
Touch sensor:
Detection of something like a touch of finger or a stylus is known as touch sensor.
It’s name suggests that detection of something.
They are classified into two types:
Resistive type
Capacitive type
Today almost all modern touch sensors are of capacitive types.
Because they are more accurate and have better signal to noise ratio.
Range sensing:
Range sensing concerns detecting how near or far a component is from the sensing position, although they can also be used as proximity sensors.
Distance or range sensors use non-contact analog techniques. Short range sensing, between a few millimetres and a few hundred millimetres is carried out using electrical capacitance, inductance and magnetic technique.
Longer range sensing is carried out using transmitted energy waves of various types eg radio waves, sound waves and lasers.
Mechanical sensor:
Any suitable mechanical / electrical switch may be adopted but because a certain amount of force is required to operate a mechanical switch it is common to use micro-switches.
Pneumatic sensor:
These proximity sensors operate by breaking or disturbing an air flow.
The pneumatic proximity sensor is an example of a contact type sensor. These cannot be used where light components may be blown away.
Optical sensor:
In there simplest form, optical proximity sensors operate by breaking a light beam which falls onto a light sensitive device such as a photocell. These are examples of non contact sensors. Care must be exercised with the lighting environment of these sensors for example optical sensors can be blinded by flashes from arc welding processes, airborne dust and smoke clouds may impede light transmission etc.
Speed Sensor:
Sensor used for detecting the speed of any object or vehicle which is in motion is known as speed sensor .For example – Wind Speed Sensors, Speedometer ,UDAR ,Ground Speed Radar .
Temperature Sensor:
Devices which monitors and tracks the temperature and gives temperature’s measurement as an electrical signal are termed as temperature sensors .These electrical signals will be in the form of voltage and is directly proportional to the temperature measurement .
PIR Sensor:
PIR stands for passive infrared sensor and it is an electronic sensor that is used for the tracking and measurement of infrared (IR) light radiating from objects in its field of view and is also known as Pyroelectric sensor .It is mainly used for detecting human motion and movement detection .
Ultrasonic Sensor:
The principle of ultrasonic sensor is similar to the working principle of SONAR or RADAR in which the interpretation of echoes from radio or sound waves to evaluate the attributes of a target by generating the high frequency sound waves .
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