INSIDE ATMEGA-16 MICROCONTROLLERS

A single chip facilitating some of the external peripherals on it designed to perform a specific function is called as a microcontroller. It is an integrated circuit having a fixed number of input and output ports, fixed data and program memory and inbuilt timer.

How it works?

A microcontroller is programmed using assembly language or embedded C, with the help of a programmer. When we turn the controller ON and connect it to the system, our system will work according to the program being run in the controller.

We would be using ATMEGA-16 microcontrollers to control our system. A 40 pins IC which have following features-

·         4 bidirectional I/O ports

·         Low power 8-bit microcontroller

·         Supports serial communication

·         1K byte internal RAM

·         512 bytes EEPROM

·         32x8 General purpose registers

·       Programming lock for software security available.

Pin Descriptions

·         VCC

Digital supply voltage.

·         GND

Ground.

·         Port A (PA7:PA0)

Port A serves as the analog inputs to the A/D Converter.

Port A also serves as an 8-bit bi-directional I/O port, if the A/D Converter is not used. Port pins can provide internal pull-up resistors (selected for each bit).

The Port A output buffers have symmetrical drive characteristics with both high sink and source capability.

When pins PA0 to PA7 are used as inputs and are externally pulled low, they will source current if the internal pull-up resistors are activated.

The Port A pins are tri-stated when a reset condition becomes active, even if the clock is not running.

·         Port B (PB7:PB0)

Port B is an 8-bit bi-directional I/O port with internal pull-up resistors (selected for each bit).

The Port B output buffers have symmetrical drive characteristics with both high sink and source capability.

As inputs, Port B pins that are externally pulled low will source current if the pull-up resistors are activated.

The Port B pins are tri-stated when a reset condition becomes active, even if the clock is not running.

·         Port C (PC7:PC0)

Port C is an 8-bit bi-directional I/O port with internal pull-up resistors (selected for each bit).

The Port C output buffers have symmetrical drive characteristics with both high sink and source capability.

As inputs, Port C pins that are externally pulled low will source current if the pull-up resistors are activated.

The Port C pins are tri-stated when a reset condition becomes active, even if the clock is not running. If the JTAG interface is enabled, the pull-up resistors on pins PC5(TDI), PC3(TMS) and PC2(TCK) will be activated even if a reset occurs.

·         Port D (PD7:PD0)

Port D is an 8-bit bi-directional I/O port with internal pull-up resistors (selected for each bit).

The Port D output buffers have symmetrical drive characteristics with both high sink and source capability.

As inputs, Port D pins that are externally pulled low will source current if the pull-up resistors are activated.

The Port D pins are tri-stated when a reset condition becomes active, even if the clock is not running.

·         RESET

Reset Input. A low level on this pin for longer than the minimum pulse length will generate a reset even if the clock is not running. The minimum pulse length is given in Shorter pulses are not guaranteed to generate a reset.

·         XTAL1

Input to the inverting Oscillator amplifier and input to the internal clock operating circuit.

·         XTAL2

Output from the inverting Oscillator amplifier.

·         AVCC

AVCC is the supply voltage pin for Port A and the A/D Converter. It should be externally connected to VCC, even if the ADC is not used. If the ADC is used, it should be connected to VCC through a low-pass filter.

·         AREF

AREF is the analog reference pin for the A/D Converter.

Integrated Development Environment

Software which helps to develop our code efficiently without much muddling efforts, all in one solution, is called Integrated Development Environment (IDE). It performs-

Compilation

Assembly

Linking

Translations

Text editing

WINAVR, CVAVR, AVR studio, etc. are some of the development software and we would prefer CVAVR as IDE for ATMEGA-16. The keywords used to develop programs are quite familiar to us in it. CVAVR stands for Code Vision Advance Virtual RISC.

Technical Workshops as a part of School Curriculum

“The technology you use impresses no one. The experience you create with it is everything.”

The ubiquity of technical gadgets in today’s market has made our lifestyle appear sophisticated. A decade ago, having a multimedia phone or using laptops appeared enough to highlight our class. Whenever we had a talk about electronic gadgets, people presumed that it would cost larger than the size of their pockets. But science and technology keep their pace a step ahead our needs. Today, the market of electronic accoutrements has its own regalia in which everyone one is getting dressed, diminishing the gap created by the ‘dollar & pound’ brothers. Everything is affordable in today’s market and can be utilized at its best. But, learning to use them is not sufficient. It is of utter importance to have a sound knowledge of ever improving technology in order to create new. We all wonder that how a mobile phone app can edit our image or how a body tattoo can generate energy from our sweat, but our lethargic behaviour toward learning puts a ‘full stop’ at a mere astonishment. Actually, we are paying to use technology and most of us haven’t tasted the pie that technology would pay us if we also begin to explore in this field.

In this advanced epoch, website designing, apps development, robotic systems and many other technical skills are used by entrepreneurs to make money with minimum capital investments. They start with a simple app and when it gains pace all around, a heavy amount is received by them too. We should also keep in mind- what we create is not new but how we present it makes it a brand. Take a simple illustration; a manual robotic car designed can work as a load carrier, mountain climber, mouse chaser, camera mover, toy car, virtual watchman, mines detector and many more. Similarly, we can develop applications by modifying the technology we use.

The technology and its applications are rarely taught in intermediate schools. Most of the institutions focus only on theory are hardly let the buddies to analyse pragmatically. Technical workshops should be given from the schools because the interesting part of science lies in its applications, which is necessary to stir up the interest of students toward efficient learning. So, it time to change the education and introduce technology in the curriculum. 

Getting Started with Electronics

What is an Embedded System?

The integration of hardware and software to perform specific functions, minimizing the need of human control is an embedded system.

·         Digital watches and cameras.

·         Calculators

·         Timer system in washing machines

·         Temperature monitoring systems

·         Automatic security systems

Embedded hardware, once programmed, is dedicated to perform that task forever.

It is designed to interact with human elements as well as external environment with the help of sensors.
Systems that doesn’t require time deadline to be completed, are called non-real time embedded systems.
Systems which are programmed to perform tasks, being controlled by time deadline are called real time embedded systems.

Components to design embedded systems

Resistors

These are the basic elements which are used to limit voltage or current supply into the appliances.

Colour	value
Black	0
Brown	1
Red	2
Orange	3
Yellow	4
Green	5
Blue	6
Violet	7
Grey	8
White	9

·         First two bands from closer side represent the integer part.

·         The next band provides power raise to 10.

·         Last band shows tolerance having different colour code as-

- 2% for red

- 5% for gold

- 10 % for silver

Capacitors

To remove the traces of noise from our output and to obtain a stabilized supply, capacitors are used.

The two types of capacitors we will be using to design our circuit are-

Ceramic capacitors

·         Parallel plate capacitors with ceramic as dielectric filled in between.

·         Do not have fixed polarity.

      Value written on it gives its capacity, for example if written 104, means 10x10⁴ pF.

      

Electrolytic capacitors

·         Cylindrical capacitors with electrolyte filled in between.

·         They have fixed polarity determined by covering over the capacitors.

·         If not connected in right polarity it may blow off.

Voltage regulator IC 7805

This is a 3 pin IC used to regulate voltage to a fixed value of 5V.

Last two digits on IC number represent the output voltage given by it.

Current up to 0.5A can be obtained from the regulator IC.

Two capacitors of 0.1pF are used at input and output ends to filter noise in respective supply.

npn Transistor BC547

The transistor holds ‘CBE’ i-e collector, base, emitter respectively in same order, when observed from flat face.

Diode 4007

This component converts bilateral current flow into a specific direction.

It can be used to avoid reverse flow of current or to prevent circuit from any blow off.

Silver line represents the negative biased point.

Diode 4148 is a zener diode.

LED

These emit energy in the form of photons due to electronic transitions in visible region of spectrum.

It performs the same what a diode can, beside, it can also be used to show output.

The current through LEDs must be lesser than 20mA, that’s why it is suggested to put 220 ohm resistor in series to it.

The one with shorter leg of LED is negative terminal.

Bread Board

Instead of wasting money on Printed Circuit at the very initial stage, we can test our circuit on bread board. A structure with bread like pores, through which connections are internally made to connect through the complete circuit, is a bread board.