Notes

Embedded systems

Embedded systems are devices that use processors to perform different tasks. It can be real-time or non-real-time. Real-time embedded systems are used where the lack of even a few milli-seconds can cause failure of an entire setup like a nuclear reactor. Non-real-time embedded systems are those where a few milli-seconds lack wouldn’t make system failure like the embedded system used in home air conditions where delay in initializing a cooling process will not be a big problem. Examples of embedded systems in daily life are the following

  • Smartphone
  • Laptop/ desktop
  • Television
  • Washing machine etc.

Robotics

Robotics is a branch of engineering that deals with the design, manufacturing, and research of robots to make them better. Nowadays much research is going on in the field of robotics. This is the future technology that is now implemented at the places where automation is required like factories, hospitals, garages, homes, offices, etc.

Information technology (IT)

IT sector deals with the usage of computers to store, process, send, and receive data, to fulfill the requirements of an organization. India is one of the leading countries in the IT field. Bangalore is the IT hub of India.

IoT (Internet of Things)

IoT is a network of smart devices like heart monitoring devices, smart TVs, smart lights, etc. to provide systems that work collaboratively and give the desired output. “Things” in IoT are the smart devices and each device differs from the other by an identifier tag which gives a unique identification number to each device.

Electronic components and Spare parts

Resistor

A resistor is a passive electronic component that is used to limit the current in the circuit. More the resistance a resistor will have, the less current will flow through the circuit. Resistance= Voltage/ Current.

Capacitor

A capacitor is a passive electronic component that is used to store electrostatic energy in the form of charges. In simple language, you can take it as a component that is used to store the charge that we can use later in a circuit. Capacitance= Charge/ Voltage

Inductor

An inductor is also a passive electronics component that blocks the changes in an electrical current (a.c.) and passes d.c. It is used in many types of an electronic circuit which a filter circuit (which converts pulsating d.c. into pure d.c.) and which is used after rectification is an example.

Diode

A diode is a passive electronic device that passes d.c. and blocks a.c. and that is why it is used in rectification operation. The most common example of rectifier circuits is your mobile phone/laptop chargers. Many types of diodes are available in the market. Some of them are the following.

  • Conventional or rectifier diode – 1N4001, 1N4007 etc.
  • Zener diode – 1N4728A, 1N4729A, 1N4764A etc.
  • LED (Light Emitting Diode) is available in many colors like Red, Green, Yellow, Blue, etc.
  • Schottky diode – SD101A etc.
  • Laser diode – It comes with the specifications like the wavelength of light, power of diode, etc.

and many other types.

Light Emitting Diode (LED)

Light-emitting diodes are two lead semiconductor devices. It’s a p-n junction diode, which on the recombination of electrons by the applied voltage, emits light. They come in different colors and sizes like Red, Green, Blue, Yellow, etc., and 5 mm, 3 mm, etc. They also categorize as normal, bright, and super bright LED which depends on the intensity of light of an LED.

Transistor

A transistor is one of the most important active electronic components that is used to amplify the a.c. signal (with the help of an external source like a battery) and also works as a switch. It comes in two configurations first is NPN and the second is PNP. Mostly we use NPN transistors because in this case, electrons are the majority charge carriers and electron’s mobility is very high in comparison with holes (which are the majority charge carriers in PNP). Some of the most common transistors used in projects are BC 547, BC 557, 2N2222A, etc.

Microprocessor

A microprocessor is an Electronic chip that has a processor to perform different mathematical and computational tasks in embedded systems. 32-bit microprocessor means that it can take at most 32-bit long data and perform different tasks on it. Famous microprocessors are Intel 8085, 8086, 80286 etc.

Microcontroller

Microcontrollers are like microprocessors that perform different computational tasks but the main difference between these is that microcontroller has inbuilt RAM, ROM, and I/O ports along with the CPU. Microcontrollers are used for specific tasks like controlling the temperature of a room (as used in Air conditions) whereas microprocessors are used for general-purpose applications like gaming, video editing, text editing, etc. Examples of some famous microcontrollers are Intel 8031, 8051, etc. Arduino uses Atmel’s Atmega 328 microcontroller.

Arduino UNO

Arduino is an open-source software and hardware company. Arduino UNO is a microcontroller-based development board that is used to make and develop different embedded and robotics projects. It uses Atmel’s ATmega-328 microcontroller. It has 14 digital Input and Output pins and 6 analog I/O pins. Arduino UNO uses a 16 MHz crystal oscillator. It operates on 5 V voltage but 6-20 V can be given at the input which will be stepped down to 5 V . Many other boards like Arduino Mega, Nano, Pro-mini, etc. are also available.

Integrated Circuits

An I.C. or micro-chip is a piece of silicon (or other semiconductor) onto which electronic circuits are made using a photo-lithography process with the help of a mask.  These circuits are the combinations of tiny “transistors” of size around (7 nm to a few hundred nm). The number of electronic circuits present in an I.C. depends upon the complexity of the circuit. A more complex circuit will contain a higher number of components whereas a less complex circuit will contain a smaller number of components. An I.C. may be as simple as a logic gate or as complex as a microprocessor.

  • Gates ICs – 7400 ( NAND gate), 7404 (NOT gate), 7432 (OR gate) etc.
  • Driver ICs – 7447 ( BCD to seven segment driver) etc.
  • Voltage regulator ICs – 7805 ( +5V voltage regulator), 7808 (+8V voltage regulator), 7910 (-10V voltage regulator) etc.
  • Processors – Microcontroller (i.e. Intel 8051, 8031, Atmel’s Atmega 328P, etc.) and the microprocessor (Intel 8085, core i3, core i5, core i7, core i9, AMD ryzen, threadripper, etc.)

Crystal oscillator

A crystal oscillator is a component that contains an “oscillator circuit”. This oscillator circuit has quartz crystal in it and uses the “Piezo electric effect“. When this quartz crystal is put under stress, it produces an electrical signal with a precise frequency which depends upon the cutting of the crystal. Arduino UNO, Mega, Nano, Pro-mini (5 V version) uses a 16 MHz crystal oscillator whereas Arduino Pro-mini (3.3 V version) uses an 8 MHz crystal oscillator.

Sensors

Sensors are electronic devices that sense the physical world quantities like temperature, humidity, light, etc., and convert them into data that a microcontroller can understand which is obviously in ‘binary form’. Here is the list of some most common sensors.

  • Ultrasonic sensor –  to sense the distance of an object
  • Infra-red (IR) sensor – to detect any IR light falling on the device… TSOP 1738,1838 is used for this purpose
  • Humidity sensor – to detect the humidity in the air
  • Temperature – to detect the temperature of an environment
  • Light sensor – to sense the falling light
  • Sound sensor – to detect the intensity of sound waves
  • Passive infra-red (P.I.R.) sensor – to detect an object
  • Gas sensor – to detect the presence and quantity of particular gas in the air
  • Soil moisture sensor – to check the moisture level of the soil
  • Bumper sensor – to detect the hit with some solid surface…. mostly used in cars
  • Vibration sensor – to detect any vibration in the device.…used in vehicles to detect accidents
  • Color sensor – to find the color of an object… since each color reflects a different amount of light…black (reflects least) and white (reflects most)
  • Fingerprint sensor – to detect the particular fingerprint pattern

and there are hundreds of sensors available out there in the market.

Motors

Motors are electrical machines that convert electrical energy into motion (mechanical energy). Motors can be divided into two categories

  • AC motors – Which uses a.c. energy to operate
  • DC motors – Which uses d.c. energy to operate

In robotics we use d.c. motors, which can be of any type like Geared d.c. motors, B.O. (battery-operated) motors, stepper motors, servo motors, etc. Motors are used in robots to rotate wheels and move the robot.

Bread-board

Breadboard is a solder-less component which means that you don’t need to solder the connections to make them interconnected with each other. You can make complete electronic circuits without any soldering. These boards are used for circuit testing purposes. Bread-board comes in different sizes which you can choose according to your project size.

Chassis

A chassis is a robot’s body that can have different interconnected metallic parts to provide rigidity to the robot. Chassis includes the following things

  • Metallic frame made up of steel or other strong metal
  • Wheels
  • Other smaller parts like nuts, bolts, connecting plates, etc.

Motor driver

A motor driver is a circuit that is used to drive the motor clockwise, counter-clockwise, or stop the motor. It is based on an H-bridge circuit for this purpose. The other important function of motor driver IC is that it supplies the required current to run the motors which is around 1 Amp. to several amperes but a microcontroller can supply on few milli amperes current which is not enough to run the motor. Most commonly we use two motor driver modules “L293D” and “L298N”.

Printed circuit board (PCB)

PCBs are the circuit boards that interconnect the different electronic components used in circuits with the help of tracks (copper paths). There is a solder mask which is green in color and whose function is to avoid any shorting between the tracks. Solder is used to fix the components at their respective places.

Bluetooth module

Bluetooth module is a breakout circuit that helps us to easily connect our microcontroller system like Arduino to the other Bluetooth device which could be your mobile phone, laptop, etc. The most common Bluetooth modules are HC-05, HC-06 (for Android devices), and HM10 (for iOS devices). It works on 2.4 GHz radio frequency. These modules are used to serially send and receive the data wirelessly without any interruption.

DTMF module

Dual tone multi-frequency (DTMF) is a module that generates different frequencies for different coming data and converts it into the digital form which could be understood by the micro-controller.

RF module

A radio frequency (RF) module uses radio frequencies to transmit data from one point to the other. The frequency used could be 30 MHz to 300 GHz but the most common frequency used is 433 MHz frequency.

MPU 6050

MPU 6050 is a 3-axis gyroscope and an accelerometer in a single chip which can provide coordinates of a device in a space so that we can understand its position, angle of tilt, and change in its speed while moving.  It uses I2C bus communication.

Battery

A battery is a device that converts the chemical energy into electrical energy. The most common battery types are Lead acid, Li-ion, and Li-polymer batteries. All of these are rechargeable batteries.

Jumper wires

Jumper wires are the connecting wires that are used to connect the different components. Here you don’t need any soldering and mostly jumper wires are used with breadboards. Jumper wires are of 3 types which are the following.

  • Male to female
  • Male to male
  • Female to female

Multi-meter

A multimeter is an electronic that used to be electro-mechanical a few years back (which had a needle mechanism). They are used to measure different electrical quantities like resistance, current, voltage, conductivity, etc.

Liquid crystal display (LCD)

LCDs are devices used to display some information which can be in the form of images, numbers, or symbols to the user. LCD comes in different sizes according to the requirement. Commonly we use 16×2 or 16×4 LCD modules, where 16 is the number of columns and 2, and 4 are the rows.

Relay

A relay acts as a switch that connects/breaks the high-power circuit. Relay uses where we want to connect low power circuit with high power (220v) main supply of your home. Without a relay 220v or higher will damage your circuit in seconds. However, the relay works on the magnetization of the coil with the help of a small relay current that protects our circuit.

Transformer

A transformer is an electrical device that is used to change the voltage level from “HIGH voltage to LOW voltage” (Step down transformer) or “LOW voltage to HIGH voltage” (Step-up transformer). But the main thing, that you will have to remember is that the total power will remain the same on both sides of a transformer and only the voltage or current level will change.

Important circuits

Rectifying circuit

A rectifier circuit is used to convert a.c. into d.c. with the help of a rectifier circuit. The rectifier circuit contains a diode and current limiting resistors. We have two types of rectifier circuits.

  • Half wave rectifier (converts only one-half cycle of the input wave)
  • Full wave rectifier (converts both half cycles of the input wave)

Full wave circuits can also divided into two parts depending on which type of diode configuration is used. Center-tap rectifier (uses two diodes) and Bridge rectifier (uses four diodes). All your mobile and laptop chargers have rectifier circuits in them.

Filter circuit

The filter circuit is used to remove the a.c. component present in the rectified d.c. wave (pulsating d.c.). It contains resistors, capacitors, and inductors to filter the a.c. component and give the pure d.c. wave at the output.

Amplifier circuit

The amplifier circuit amplifies (boosts) the a.c. signal with the help of external d.c. source. This circuit contains a transistor, resistor, d.c. source and coupling circuit if required.

Timer circuit (IC 555)

A timer circuit is used to generate the different shapes of the waves. Normally we use an IC 555 circuit to take the square of rectangular pulses to drive an LED at different rates.