Basic Components

This text will aim to give a basic introduction of the components that will be used in the workshop and to familiarise with their general uses.

• Breadboard

  
  

  A breadboard is a construction base for prototyping of electronics. It is used to build and test circuits quickly before finalizing any circuit design. It has many holes into which circuit components like ICs and resistors can be inserted.

• LED

  

  A Light Emitting Diode or LED is a semiconductor diode that produces light when a voltage is applied across it. It is primarily used for lighting purposes in electronics and automative industries.

• Resistors

  

  A resistor is a passive two-terminal electrical component that implements electrical resistance as a circuit element.

• Multimeter

  

  A Multimeter is a device that can measure multiple electrical properties. It is mostly used in debugging our circuits.

• Arduino Uno

  Arduino is basically an open source electronics platform providing both software and hardware. Arduino Uno is perhaps the most widely used microcontroller developed by Arduino.

  On a personal note, the board is pretty robust and is easy to work around.

  Your board looks like this,

  

• Arduino Cable

  

  This is a Cable For Arduino UNO/MEGA (USB A to B). You can use it to connect “Arduino Uno”, “Arduino Mega 2560″ or any board with the USB female A port of your computer.

• LDRs

  

  A Light Dependent Resistor or LDR is basically a resistor whose resistance varies depending on the intensity of light falling on it. It can be used in building alarm clocks, burglar alarm circuits, etc. We would be using these to build a Light Follower robot in the workshop.

• IR Module

  

  IR Sensors are crucial components for building the Line Follower robot. These sensors will be required to keep our bot on the path and is pretty much what will guide our bot.

• BO Motors

  

  Bo motor (Battery Operated) lightweight DC geared motor which gives good torque and rpm at lower voltages. We will be using 2 BO motors for our purpose. These motors will be connected to the L293D motor driver which will help us control the direction of motion of the motor as well as the torque generated.

• L293D Motor Driver

  

  A motor driver is an integrated circuit chip which is usually used to control motors in autonomous robots. Motor driver act as an interface between Arduino and the motors . L293D, the motor driver included in your kit, is one of the most popular motor drivers.

• HC-SR04

  

  HC-SR04 is an Ultrasonic Sensor that is used for detecting the distance to an object. This sensor would be a key component in building the Obstacle Avoidance robot.

• HC-05

  

  HC-05 is a bluetooth module that gives bluetooth properties to your robot. It enables you to wirelessly control your robot using your phone. This would be a key component in building the Bluetooth Controlled Bot.

• Jumper Wires

  

  Jumper wires are simply wires that have connector pins at each end, allowing them to be used to connect two points to each other without soldering. Jumper wires are typically used with breadboards and other prototyping tools in order to make it easy to change a circuit as needed.

• Chassis

  A chassis is basically the load bearing framework of an artificial object, say a car or in our case a robot. It provides structural support to our framework. Following are few pictures to give an idea what a chassis would look like -

   

  

How to make connections on a Breadboard?

As mentioned before, a breadboard is a circuit board that is used to make temporary circuits. It is a device having electronics and test circuit designs. The electronic elements inside the electronic circuits can be interchanged by inserting the terminals and leads into holes and later connecting it with the help of appropriate wires.

The metal strips are laid out as shown below. Note that the top and bottom rows of holes are connected horizontally and split in the middle while the remaining holes are connected vertically.

In the below image, you can see how all holes in the selected row and selected column are connected together. The set of connected holes can be called a node.

To interconnect the selected row (node A) and column (node B) a cable going from any hole in the row to any hole in the column is needed:

Now the selected column (node B) and row (node A) are interconnected:

Thus, in a Breadboard

You can refer to the following video for more information - Understanding How Breadboards Work

Basic LED - Breadboard connection

The below image shows how to make a simple LED - Breadboard connection.

Explanation

Power connections:

• The positive terminal of the 9V battery is connected to one of the horizontal rails on the breadboard, in this case the one marked with the + sign, through a Red wire.
• Similarly, the negative terminal of the 9V battery is connected to the other horizontal rail on the breadboard, in this case the one marked with the - sign, through a Black wire.

LED connections:

• The positive terminal of the LED, which is longer and bent, is connected to the positive rail (+) on the breadboard through a Red wire.
• The negative terminal of the LED, which is shorter and straight, is connected to a resistor.

Resistor connections:

• One end of the resistor is connected to the negative terminal of the LED.
• The other end of the resistor is connected to the negative rail (-) on the breadboard through a Black wire.

You can take a look at the TinkerCAD Simulation here.

Using a Multimeter

What is a multimeter?

A multimeter is a device that can measure many electrical properties depending on its mode.

Connections of Multimeter

1. Knob:- This is used to select the functions and desired ranges as well as to turn ON/OFF the device.
2. Display:- It is used to display the values it reads based on the functions it selected.
3. “COM” Jack:- Use to plug in black connector for negative test lead.
4. “V ΩmA” Jack:- Use to plug in red connector for positive test lead for all voltage, resistance, and current ( up to 200mA ) measurements.
5. “10 A” Jack:- Use to plug in red connector for positive test lead for current ( between 200mA and 10A ) measurement. There is no fuse for the "10A" jack. To use safely, each measurement can not last for more than 10 seconds, and the interval between each measurement must be more than 15 minutes.

Function’s of Multimeter

AC Voltage (V~)

• There will be a region up-right to the knob marked with the above symbol.
• It is used to measure AC voltages between 2 terminals.
• The various options given in this specify the maximum AC voltage it is going to read.
• Readings will be shown in V.

DC Voltage (V⎓)

• There will be a region up-left to the knob marked with the above symbol.
• It is used to measure DC voltages between 2 terminals.
• The various options given in this specify the maximum DC voltage it is going to read.
• If you select 2000m or 200m, the reading will be shown in mV. For other cases, it will show in V.

DC Current (A⎓)

• There will be a region right to the knob marked with the above symbol.
• It is used to measure DC currents across a circuit.
• The various options given in this specify the maximum DC current it is going to read.
• For measuring upto 10A, connect red connector in “10A” jack. For other than 10A, connect red to “V ΩmA” jack. If you select 2000μ, then the readings will be displayed in μA. If you have selected 20m or 200m, it will show reading in mA and if you have selected 10A, it will show in A.

Caution - Do not connect the multimeter directly with a voltage source in this mode. If you do so, you will end up blowing your multimeter.

Resistance (Ω)

• There will be a region bottom-left to the knob marked with the above symbol.
• It is used to measure resistance between 2 terminals.
• The various options are used to select the maximum resistance.
• If you select max resistance 2000k, 200k, 20k, it will show reading in kΩ. For the rest of the cases, readings will show in Ω.

Continuity ()

• There will be a region bottom-left to the knob marked with the above symbol.
• When you will touch 2 terminals to some point on a circuit, if there is continuity (if those points are directly connected to each other), it will make ‘beep’ sound.

OFF mode

• Located at top of knob.
• For switching off multimeter.

Microcontrollers

What is a microcontroller?

A microcontroller is a compact integrated circuit designed to govern a specific operation in an embedded system. A typical microcontroller includes a processor, memory, and input/output (I/O) peripherals on a single chip.

Also known as embedded controllers or microcontroller units (MCUs), they are found in a variety of devices, including automobiles, robotics, office equipment, medical devices, mobile wireless transceivers, vending machines, and home appliances. They are essentially simple miniature personal computers (PCs) with no complex front-end operating system, designed to operate small features of a bigger component (OS).

How do microcontrollers work?

A microcontroller is embedded inside a system and controls a single function. It accomplishes this by employing its core Processor to evaluate data received from its I/O peripherals. The microcontroller's temporary information is stored in its data memory, where the processor accesses it and decodes and applies the incoming data using instructions stored in its programme memory. It then communicates with its I/O peripherals and takes the required action.

Core Elements of a Microcontroller

The processor (CPU) A processor might be compared to the device's brain. It interprets and responds to a variety of commands that control the microcontroller's operation. This includes basic arithmetic, logic, and input/output (I/O) operations. It also performs data transfer operations that send commands to other embedded system components.

Memory The memory of a microcontroller is used to retain the data that the processor receives and to respond to commands that it has been programmed to carry out. There are two types of memory in a microcontroller:

Program memory is where the CPU keeps long-term information about the instructions it executes. Program memory is non-volatile memory, which means it may store data indefinitely without the need for a power source.

Data memory is needed to store temporary data while the instructions are being executed. Data memory is volatile, which means that the data it stores is only transient and is only kept if the device is powered up.

I/O peripherals The processor's input and output devices serve as its interface to the outside world. The input ports take in information and transfer it to the processor as binary data. The processor receives that data and sends the necessary instructions to output devices that execute tasks external to the microcontroller.

While the processor, memory, and I/O peripherals are the most important components of a microprocessor, other components are typically incorporated as well. Supporting components that interface with the memory and CPU are referred to as I/O peripherals. Peripherals are a broad category that includes a wide range of supporting components. Because they are the method via which the processor is applied, having some form of an I/O peripheral is essential to a microprocessor.

Examples of Microcontrollers

• Most Arduino boards consist of an Atmel 8-bit AVR microcontroller (ATmega8, ATmega168, ATmega328, ATmega1280, or ATmega2560)
• ARM is a family of microcontroller developed by makers like ST Microelectronics and Motorola.

Fig 1.2: Arduino with ATmega328 Microcontroller

Introduction to Arduino

Arduino is an open-source electronics platform based on easy-to-use hardware and software. It consists of both a physical programmable circuit board (a microcontroller) and a piece of software, or IDE (Integrated Development Environment) that runs on your computer and allows you to write and upload computer code to the physical board.

Arduino boards are able to read inputs such as lights on a sensor, pressure on a button, etc., and turn them into desired outputs such as activating a motor or turning on an LED. The set of instructions required to perform such tasks are given to the Arduino board using the IDE.

Unlike most previous programmable circuit boards, the Arduino does not need a separate piece of hardware (called a programmer) to load new code onto the board - you can simply use a USB cable. Additionally, the Arduino IDE uses a simplified version of C++, making the programming easier.

Arduino manufactures a wide range of boards. These have different sizes, different microcontrollers, and different processing capabilities. The Uno is one of the most popular boards in the Arduino family and an excellent choice for beginners.

Main components

1. Power (USB): The Arduino UNO is connected to a power source via a USB cable that is terminated in a barrel jack. The USB connection is also used to load code onto your Arduino board. The recommended voltage for most Arduino models is between 6 and 12 Volts. A power supply greater than 20 Volts will damage the Arduino board.

2. Pins: The pins on the Arduino board are where the connections are made in order to construct the required circuit (in conjunction with a breadboard and connecting wires). The Arduino has several kinds of pins, each of which is used for a different purpose.

   • 5V and 3.3V Pins: These pins are used for power supply to the Arduino. 5V or 3.3V is sufficient for most of the simple components used.
   • GND: These pins are used to 'ground' the circuit.
   • GPIO (General Purpose Input Output Pins): These are specific pins that are programmed to input/output signals.

3. RX and TX LEDs: RX and TX stand for Receiving and Transmitting, and these LEDs are used to indicate Serial communication (like when we're loading a new program onto the board). The TX and RX LEDs blink whenever there is communication between the onboard microcontroller and the computer through the USB to serial converter chip present near the USB port. The lighting up of the LEDs indicates the direction of the flow of data. When a bit of data goes from the Arduino board to the computer, the TX LED glows. The RX LED glows when a bit of data goes from the computer to the Arduino board.

4. Reset Switch: This functions as a reset button. Pushing it will temporarily connect the reset pin to ground and restart any code that is loaded on the Arduino. This can be very useful if your code doesn't repeat, but you want to test it multiple times.

5. Main IC: This functions as the brain of the Arduino. The main IC on the Arduino is slightly different from board type to board type but is usually from the ATmega line of IC's from the ATMEL company. This can be important, as you may need to know the IC type (along with your board type) before loading up a new program from the Arduino software. This information can usually be found in writing on the top side of the IC.

6. Voltage regulator: It is used to regulate the power supply to the Arduino board. The regulator still has limitations, and hence a supply greater than 20 Volts must not be used as it may damage the board.

Arduino Uno

Arduino Uno is a microcontroller board based on the ATmega328P. It has 14 digital input/output pins (of which 6 can be used as PWM outputs), 6 analog inputs, a USB connection, a power jack, an ICSP header, and a reset button. It contains everything needed to support the microcontroller; simply connect it to a computer with a USB cable to get started.

General Purpose Input Ouput Pins (GPIO)

GPIO pins are programmed to input/output signals. These bridge the gap between programming and electronics. There are two types of GPIO pins:

• Digital GPIO pins
• Analog GPIO pins

1. Digital Pins

The digital pins in the Arduino are labelled 0-13 (14 pins). These pins can be used for both digital input as well as digital output.

The pins on the Arduino that are marked with a tilde symbol (~) are known as PWM pins, and are used for analog output. On most Arduino boards (those with the ATmega168 or ATmega328), the PWM pins are 3, 5, 6, 9, 10, and 11 (6 pins). More information about PWM will be provided later.

Pin 13 of the Arduino Uno has a special function. It has an LED and a resistor attached to it. This makes it difficult to configure in the input modes.

Pins 0 and 1 (named RX and TX) are for serial connection and should not be used for other uses.

In order to use the pins for digital input, the digitalRead() function is used. In order to use the pins for digital output, the digitalWrite() function is used.

NOTE - The digitalRead() and digitalWrite() functions will be explained later.

2. Analog Pins

The analog pins in the Arduino are labeled A0-A5 (6 pins). The Arduino has an analog-to-digital (A/D) converter. The converter has 10 bit resolution, returning integers from 0 to 1023. Hence the pins can read analog input voltages between 0 and the operating voltage (usually 5 V). This input is mapped to a value between 0 and 1023 appropriately using the analog to digital converter.

The analog pins are primarily used for analog input signals. But they can also be used like digital GPIO pins (HIGH or LOW input/output). Thus, pins marked as "ANALOG IN" on the board can work either as analog input (using the Analog to Digital Converter), digital input, or digital output.

In order to use the pins for reading analog input signals, analogRead() function is used. NOTE - You will learn more about the analogRead() function in the further sessions.

NOTE - The analogWrite() function is reserved to PWM pins. A more detailed explanation of PWM pins, their function, and the analogWrite() function will be provided later.

Digital Vs Analog

By the time you are reading this, you would be having a fair idea of what an Arduino is, and what exactly are GPIO pins. On a brief note, Arduino is a microcontroller, while GPIO pins stand for General Purpose Input Output pins. These GPIO pins are further classified into Digital and Analog pins. Now let’s look into what these are and by the end of this document let’s try to make a small circuit using Arduino and a LED.

Before we look into Digital and Analog pins, let's see what are Digital and Analog Signals.

Signals

Signals, in electrical engineering, mean time-varying quantities, usually voltages. These signals are of two types, one is Digital Signal, other is Analog Signal.

Digital Signals

Digital signals refer to signals which are finite or discrete. Meaning different values passed by these signals are finite. For example, in Arduino the digital signals that can be passed are two, **$5V$ and $0V$**. They can be more than two too. But remember, Digital signals are never infinite.

This is how a Digital Signal looks like.

Analog Signals

Unlike Digital signals, Analog Signals are infinite. Meaning it can take any number of values, but usually restricted in an continues interval. For example, in Arduino, the Analog signals sent can vary between $0V$ and $5V$, both inclusive.

This is how a Analog Signal looks like.

Getting Started With Arduino

You will be learning how to talk to your Arduino and interface it with other sensors to make it smarter.

The Sketch

Every individual program that is written for the Arduino is called as a "sketch", the most basic of all the sketches is the "blank sketch" its the first sketch you see when you open a new IDE page. Which kinda looks like this

void setup(){
    // Code written here will be only be executed once

}

void loop(){
    // Code written here will be run indefinitely

}

Go ahead and open your IDE, open a new sketch in case you have some other sketch pre-loaded.

Every (mostly) arduino sketch has two components and they are the void setup() and the void loop().

void setup() The setup() function is called when a sketch starts. Use it to initialise variables, pin modes, start using libraries, etc. The setup() function will only run once, after each power up or reset of the Arduino board.

In layman terms, the setup() part of the sketch contains code that needs to be only run once.

void loop() After creating a setup() function, which initialises and sets the initial values, the loop() function does precisely what its name suggests, and loops consecutively, allowing your program to change and respond. Use it to actively control the Arduino board.

In layman terms, the loop() part of the sketch contains code that is to be run indefinitely.

Now that you understand the basic layout of a sketch, lets start learning how to code.

Input/Output

Like the laptop/desktop through which your currently reading this walk-through can be connected to external devices like keyboards, mouse, printers, joysticks. The Arduino which is a microcontroller can also be connected to external input/output devices (input devices are usually called sensors) and just like devices for your laptop most of these sensors can be classified into two categories.

1. Input
2. Output

The names are self-explanatory but lets go through a few examples for better understanding.

Just like your laptop has USB, HDMI and microUSB ports that can be used to connect external devices, the Arduino has a set of pins called the GPIOs (General Purpose Input/Output pins) that can be used to connect external devices to the Uno.

pinMode()

Now that you know what kinda external devices you will be working with its high time you also learn how to let your arduino know what device it is about to work with using pinMode().

pinMode() Configures the specified pin to behave either as an input or an output. See the description of digital pins for details on the functionality of the pins.

Example Sketch

void setup(){
    // The "8" refers to the digital pin 8 on the arduino board
    pinMode(8,INPUT); // for an INPUT device
    // The "9" refers to the digital pin 9 on the arduino board
    pinMode(9,OUTPUT); // for an OUTPUT device
}

void loop(){

}

Since the nature of a device (input/output) and the pin its connected to, doesn't change mid-program, its often sufficient to let the Arduino know about the devices its dealing with once at the start of the sketch, hence pinMode() is placed inside the void setup() and not inside the void loop().

The pin numbers for the Arduino board are mentioned on the board and can be used as it is inside the pinMode() function.

Talking Digital

Now that the Arduino has an heads up about the kind of device its dealing with its time we start talking with these devices.

Most of these devices while they can be Input/Output can be also classified as Digital/Analog.

Digital Devices Examples include push buttons/switches that can either be ON(Logic HIGH) or OFF(logic LOW), these devices have discrete set of states in which they can exist.

Analog Devices Examples include LED, Motors, LDR these devices have a continuous set of states in which they can exist. For example an LED can stay turned ON with different amounts of brightness and a motor can be rotating at different speeds based on the control voltage.

NOTE: Some devices can be both digital and analog based on how they are interfaced.

digitalWrite()

Since digital devices usually have only two known states either HIGH(ON) or LOW(OFF), we will be using the digitalWrite() function to either make a pin go HIGH or LOW, therefore turning ON or OFF the external device connected to the Arduino pin.

A pin in its HIGH state is set to 5 Volts, a pin in LOW state has 0 Volts.

NOTE: A pin has to be set to OUTPUT using pinMode() before you can do a digitalWrite() on it

Turning on an LED

void setup(){
    /* LED_BUILTIN is a special keyword for the inbuilt LED connected
    to digital pin 13 on the arduino, it is usually used for debugging */
    pinMode(LED_BUILTIN,OUTPUT); // Setting the LED as an OUTPUT device
}

void loop(){
    digitalWrite(LED_BUILTIN,HIGH); // Turning on the LED by sending it 5V
}

Compile and upload the above sketch, you should see a tiny orange LED near the digital pin 13 light up, congratulations on your first step towards getting to play with digital devices.

NOTE: Upload a new "blank sketch" after your done staring at the LED, if you don't want it to be turned ON forever. Alternatively you can change the HIGH to LOW in the above sketch and upload it as well.

Now that we know how to turn ON an LED, let us go one step further and make it blink (Turn ON and OFF periodically).

The most intuitive way of doing this would be to first turn ON the LED and then turn it OFF and do this in a loop forever, which when translated into code looks like this

Blinking Attempt 1

void setup(){
    // Set the pin (D13) the LED is connected to as OUTPUT
    pinMode(LED_BUILTIN,OUTPUT);
}
void loop(){
    digitalWrite(LED_BUILTIN,HIGH); // Turn the LED ON
    digitalWrite(LED_BUILTIN,LOW); // Turn the LED OFF
}

Compile and upload the above sketch and try to look very closely at the LED you should see it flicker very slightly, just kidding don't strain your eyes too much you won't be able to see it blink unless your Barry Allen, to help normal mortals make sense and visualise digital signals that are usually super fast, humans have invented a few instruments (Logic Analyzers, Oscilloscope). I went ahead and connected a logic analyzer to see exactly what's happening to the LED in the above sketch.

Lo and behold, the LED does blink but it stays on for a mere fraction of 3.375 microseconds and stays off for another 3.375 microseconds, welcome to the world of an Arduino Uno, the ATmega328p thanks to the 16MHz external crystal runs at such incredible speeds due to which it appears like as if the LED has never been turned OFF.

Now that we know whats causing the problem its time we try to fix it.

Microprocessors

What is a microprocessor?

A microprocessor is an integrated circuit (IC) that houses the central processing unit (CPU) of a computer . It is a clock-driven, register-based programmable multipurpose silicon device that accepts binary data as input and processes it according to instructions stored in the memory.

Why we need a Microprocessor?

A microprocessor, like our brain, can be trained to perform any task. Based on its instruction set and capabilities, it can be programmed to perform anything we desire. When we try to solve a problem without programming, the solution can be exceedingly complex.

When we try to solve a problem without programming, the solution can be exceedingly complex.

Assume you wish to construct a large structure. The use of BRICKS will simplify and reduce the cost of building. It will also allow you to design the building in whatever shape or size you like. The bricks that you can employ to solve your problem are instructions stored in a microprocessor. You can quickly solve difficult programmes by following those guidelines.

How does a Microprocessor work ?

A processor is the brain of a computer which basically consists of Arithmetical and Logical Unit (ALU), Control Unit and Register Array.

• ALU performs all arithmetic and logical operations on the data received from input devices or memory.
• Register array consists of a series of registers like accumulator (A), B, C, D etc. which acts as temporary fast access memory locations for processing data.
• Control Unit controls the flow of instructions and data throughout the system.

So basically a microprocessor takes input from input devices, process it as per instructions given in the memory and produces output.

Advantages of Microprocessors

Low Cost Microprocessors are available at low cost due to integrated circuit technology which reduces the cost of a computer system.

High Speed Microprocessor chips can work at very high speed due to the technology involved in it. It is capable of executing millions of instructions per second.

Small Size Due to very large scale and ultra large scale integration technology, a microprocessor is fabricated in a very less footprint. This will reduce the size of the entire computer system.

Versatile Microprocessors are very versatile, the same chip can be used for a number of applications by simply changing the program (instructions stored in the memory).

Low Power Consumption Microprocessors are usually manufactured using metal oxide semiconductor technology, in which MOSFETs (Metal Oxide Semiconductor Field Effect Transistors) are working in saturation and cut off modes. So the power consumption is very low compared to others.

Less Heat Generation Compared to vacuum tube devices, semiconductor devices won’t emit that much heat.

Reliable Microprocessors are very reliable, failure rate is very less as semiconductor technology is used.

Portable Devices or computer system made with microprocessors can be made portable due to the small size and low power consumption.

Examples of Microprocessors

• Intel 4004 – The First Microprocessor
• Intel 8085
• Intel 8086
• Intel Pentium 4
• Intel Core i7
• AMD Athlon

Key differences between Microcontrollers & Microprocessors:

Here is a YouTube video you might refer to: Difference Between MicroController & Microprocessor. (use subtitles)