Tutorials

This tutorial  will help you to understand the necessity of the PCB. Here, I have described the evolution of PCB in different steps. Connecting a circuit without any soldering gun or breadboard is a complex process. I tried to connect an amplifier circuit with a transistor, four resistors, and three capacitors, which you can see in the video.

If we connect different electronics components directly with wire or their leads, we have to face a lot of problems like, loose connection, problems in troubleshooting, low reliability, low durability etc. Also if we try to move it from one place to other, we may lose the connections due to no physical support. The only solution to avoid these all problems is “PCB”.PCB:PCB stands for “Printed circuit board”. In this, wire connections printed as copper tracks. It can provide physical support to the circuit. It can avoid loose connections, and testing and troubleshooting the circuit may become also simple. 

KiCad is free software suit for EDA (Electronic design automation), which was created in 1992 by Jean-pierre charras. It has GNU and GPL licenses. I have selected KiCad software to explain PCB tutorials. Since it is open source software, anyone can try this and practice my tutorials. Work-flow:Before  getting started with KiCad, we must know about some basics and work flow of KiCad. In this tutorial, I am going to explain KiCad work flow, step by step. Please follow the same procedure when working with KiCad.

When we are designing a PCB in any CAD software, we need to find suitable components. Like, if we need resistor, we must be clear about component type, dimensions (optional), SMD component or through hole component, and different parameters. Any EDA software consists of components libraries. We can select a required component from library, but the library may not have all the components. If we need any component which is not present in the library, then we need to create and save it in the library  so as to use it in future. In KiCad, we can use library editor to create a new component. Library editor is a part of Eeschema.  Before creating a component we need to gather sufficient details about component, like pin diagram, pin configuration, its size, shape, dimension etc. So before starting library editor, go though the component data sheet.

In small circuits, we can connect components directly with wire (using “place wire” option). But in complex circuits like motherboard circuit, we may have to establish a lot of connections between different sections, whereby many connections may overlap. So, there is a chance of getting confused in circuit designing. Also, the probability of getting errors is more. We can overcome this problem by using labels or Net names (Net Labels). Net is a simple electrical connection between components.  We can create Net by using place wire.

In PCB designing, the first step is Creating circuit or schematic capture. In this, we have to draw the schematic with necessary Electronic components. This step includes adding components, connections with wire, verifying the circuit, etc. To create a circuit in KiCad, we have to use Eeschema. It is powerful schematic capture software distributed as part of KiCad and is limited only by the available memory. Thus, there is no real limitation to the number of components, component pins, connections, or sheets. In the case of multi-sheet diagrams, the representation is hierarchical. Note:  Above table contains only some commonly used and important Eeschema options. I haven’t covered all  of them.

Security in IOT cannot be an afterthought. It is an integral part of IOT development. The idea of IoT is not only to connect the normal daily things to the Internet but also to transfer the data securely among various end points so that smart IoT applications are not only efficient and successful in fulfilling various personal and professional requirements but also highly reliable.

In the previous tutorials, MQTT protocol packets and MQTT security mechanisms were discussed. Now it’s time to start getting hands dirty. For creating a communication network in which multiple IoT devices can communicate with each other via a MQTT broker, it is important to configure IoT devices as MQTT clients. The MQTT is developed on the top of TCP/IP stack, so the devices must have TCP/IP stack with them if they want to communicate to each other via MQTT broker.  

In the previous tutorial, it was learnt that how a smart phone and a PC can be set up as MQTT clients and their connection with an MQTT broker can be established. The smart phone was configured as an MQTT client using an android MQTT app – IOT MQTT Dashboard while the PC was configured as MQTT client using a chrome add-on – MQTTLens.Now, in this tutorial, these MQTT clients – Mobile and PC will be made to communicate with each other using MQTT protocol. The communication between the MQTT clients is only possible via MQTT broker.

Security is a prime concern in any IoT application development. The data from the IoT devices is passed to the server/cloud where it may be stored temporarily or for long time to generate analytics. The transportation medium through which the data is passed from the IoT device to the cloud must be secured with implementation of various IoT security measures, so that the data could not be hacked by any Man-in-the-Middle attack.  

Internet of Things is meant to empower objects of day to day use with embedded electronics and IT infrastructure. It aims to connect these objects in real time with the internet network and allow them to communicate with other co-located or remote objects. For communicating with each other, the IOT devices need to follow protocols. An application developer need to take care primarily of the implementation of application layer protocols while usually the implementation of network and transportation layer protocols remain at the hand of network administrators or network programmers.

In the previous tutorial, ESP8266 module was used to design a Home Area Network to control an LED light from a remote PC. The PC client was used to send control signals to switch on and off the LED light in the Home Area Network. In this tutorial, the ESP module will be interfaced with DHT-11 temperature sensor and temperature  data will be sent to the PC client for real-time temperature monitoring. In this project, instead of LED, the DHT-11 sensor will be interfaced with the ESP8266 on ESP Client side.

Everyone must be familiar with the term – Switched Mode Power Supply or SMPS. Yes, they are used in every personal computer. In fact, the Switched Mode Power Supply is widely used with many other devices. Once it is understood that what SMPS actually is, its countless applications can be easily imagined.  An SMPS is used for converting the electronic power supply efficiently. Any SMPS has some storage components which store electrical energy to supply to the load device and some switching components which turn on and off at high frequencies charging and discharging the storage components.

Universal Serial Bus (USB) is the de facto interface for computer peripherals to communicate with the personal computers. The interface that saw the light of day around the mid-1990s was a joint effort of seven companies – Compaq, DEC, IBM, Intel, Microsoft, Nortel, and NEC. These companies were aiming to replace the then parallel ports and the external power chargers with a universal communication standard that could simplify data exchange and could double duty to supply power as well.Nowadays, USB is the standard and must-have interface on almost all motherboards, single board computers and the embedded microcontroller boards and almost every digital peripheral from regular computer peripherals like keyboard, mouse and joysticks to smart digital devices.

In this tutorial, an open loop boost converter SMPS will be designed. The Boost Converter is one of the topologies of Switched Mode Power Supply (SMPS). It has a DC source as Input power like a battery, generator or rectifier. In the case of a boost converter, the output power is always greater than the input power.So, the boost converter circuit will step up the power from one DC level to a higher DC level. The method of converting one DC voltage to a different DC voltage is called DC to DC conversion. The boost converter is a DC to DC converter which steps up the input signal to the higher voltage level.

Network is the OSI Level 3 layer and is the internet layer in the TCP-IP model. Like Physical and MAC layers, network layer is also part of the infrastructure layer in IOT reference architecture.  This layer is responsible for addressing and routing of data packets. At this layer, the datagram from transport layer are encapsulated to data packets and delivered to their destinations using IP addressing. IPv4 had been the standard protocol for network layer until now. 

In the previous tutorial, various physical and media access control (MAC) protocol for Personal Area Network (PAN), Home Area Network (HAN) and Local Area Network (LAN) were discussed. In this tutorial, physical and MAC protocols based on RFID and mobile standard will be discussed. There are the following RFID based protocol stacks: RFID, DASH7, NFC.There are the following common mobile standards which are evolving to accommodate IOT applications

Service Discovery layer has a prominent role in an IOT architecture. It is the service discovery or service management layer which differentiates an IOT network with that of typical internet network. The IOT devices need to connect and communicate with web or cloud based services and applications for IOT implementation. The cloud or web services and applications run on host computers which are identified by unique IP addresses on a network. In order to avail a cloud based service, the IOT devices must be connected with the computers (servers) hosting those services or applications. So, there are some protocols designed to resolve host IP addresses rendering IOT services and applications

Application layer refers to OSI Level 5, 6 and 7. It is application layer in the TCP-IP model. In IOT architecture, this layer lies above the service discovery layer. It is highest layer in the architecture extending from the client ends. It is the interface between the end devices and the network. This layer is implemented through a dedicated application at the device end. Like for a computer, application layer is implemented by the browser. It is the browser which implements application layer protocols like HTTP, HTTPS, SMTP and FTP. Same way, there are application layer protocols specified in context to IOT as well.