Interfacing DC motor to 8051

admin August 2, 2012 20 Comments
This article shows how to interface a DC motor to an 8051 microcontroller. Interfacing DC motor to 8051 forms an essential part in designing embedded robotic projects. A well designed 8051-DC motor  system  has essentially two parts. Firstly an 8051 with the required software to control the motor and secondly a suitable driver circuit. Most of the DC motors have  power requirements well out of the reach of a microcontroller and more over the voltage spikes produced while reversing the...
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Operators-Expressions and Escape Sequences in C -Chapter 3

jojo June 26, 2012 8 Comments
We are into third chapter of C programming in which we will discuss operators, operands, expressions and escape sequences. I assume that you have already gone through Chapter 1 – Data Types in C and Chapter 2 – Variables and Keywords in C. Operator – An operator is usually a symbolic representation of a particular operation. Ex:- +  means addition * means multiplication etc. Operand – An operand is usually the data upon which the operator performs an action....
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Variables and Keywords in C-Chapter 2

jojo June 22, 2012 1 Comment
In this chapter, I would like to explain variables and keywords in C language. I hope you have already gone through Chapter 1 – Data Types and Constants in C. Image Courtesy Variables A variable can be defined in many ways. At the basic level, a variable can be defined as a memory location declared to store any kind of data (which may change many times during program execution). It can also be defined as any quantity/entity which may...
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Interfacing Seven segment display to 8051

admin January 23, 2018 57 Comments
A Note about 7 segment LED display. This article is about how to interface a seven segment LED display to an 8051 microcontroller. 7 segment LED display is  very popular and it can display digits from 0 to 9 and quite a few characters like A, b, C, ., H, E, e, F, n, o,t,u,y, etc. Knowledge about how to interface a seven segment display to a micro controller is very essential in designing embedded systems. A seven segment...
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Data Types and Constants in C-Chapter 1

jojo June 20, 2012 7 Comments
To use any language in communication (to write/to speak), we need to understand it’s grammar first.  In the case of a programming language like C, the scenario is same as in the case of a communication language. We need to understand the grammar of C programming language first. So here begins:- In this article we explain Data Types and Constants The basic grammar of C can be explained through:- Data Types Constants Variables and Keywords Operators and Operands Control...
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External Interrupts handling in 8051

jojo August 16, 2012 8 Comments
In this article, I would like to introduce you to the concept of interrupts, how interrupts work, vector address, interrupt priority and how to write an ISR (interrupt service routine). “Interruption” in English language means a deviation from the normal routine. We know the processor is always busy executing some kind of instructions. What if there  occurs an urgent condition that we need to pause the processor from its current activities for some time and make it execute/do something...
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GPOS versus RTOS for an Embedded System

jojo June 12, 2012 7 Comments
Difference between a GPOS (Normal General Purpose Operating System) and an RTOS (Real  Time Operating System) The whole purpose of this article is to outline the basic differences between a GPOS (General Purpose Operating System) or a Normal OS as many people call it and an RTOS (Real Time Operating System). Let’s have a look. Image Courtesy The basic difference of using a GPOS or an RTOS lies in the nature of the system – i.e whether the system...
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The Facebook Wall Caption Contest – Winner Announced

jojo June 19, 2012 No Comments
WINNER ANNOUNCED Hi friends, The winner is – Indrajit Biswas ( We have contacted him over Facebook. Now awaiting his reply. Here is the screen shot of winning selection. Hello friends,  We are back with a cool contest using Facebook. This contest is open for any one with a Facebook account.  You only need to do two things to be a part of this exciting contest. 1) Like our website’s page in Facebook – here – CircuitsToday Facebook Page ...
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Interfacing LED and push button switch to 8051

admin June 18, 2012 19 Comments
This article is all about how to interface push button switches to an 8051 microcontroller. Push button switches are widely used in embedded system projects and the knowledge about  interfacing them to  8051 is very essential in designing such projects. A typical push button switch has two active terminals that are normally open and these two terminals get internally shorted when the push button is depressed. Images of a typical pushbutton switch is shown below. Circuit diagram. The circuit diagram for...
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Embedded Systems Career-An Outline

jojo June 6, 2012 149 Comments
Many students are not aware of the lucrative opportunities available in the field of Embedded Systems. Most graduates go after the popular “IT” industry to seek a good career. I think there are 2 reasons for this 1)lack of awareness 2) entry barrier. While studying most students may come across the name “Embedded Systems”. Apart from that they may not be aware of -“what is an embedded system”, how do they work, what knowledge and skills should be acquired...
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The story of Fibonacci series

jojo June 12, 2012 9 Comments
All of you must have heard about the term “Fibonacci series”. Many of you (including me) might have written programs in different programming languages to generate a “Fibonacci series”. It is quite interesting to see that tutorials of all programming languages would contain a problem to generate fibonacci series upto “N” terms.  Well, this made me a little curious. What is so important with this particular series? In mathematics, there may be a 100 or 1000 types of series...
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8051 Programming Tutorial-Chapter 1

jojo June 5, 2012 16 Comments
This article series is developed to teach you 8051 micro controller programming. I have divided this programming tutorial into a series of chapters as shown below. So you can start with Chapter 1 and then move to chapter 2 and chapter 3 and so on. So let’s begin the journey right now!  Note: Next chapters 1,2,3.. are under development phase. Please visit this page again for updates. Note: To test any of these program or to write one your...
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Interfacing 16×2 LCD with 8051

admin May 22, 2017 32 Comments
LCD display is an inevitable part in almost all embedded projects and this article is about interfacing a 16×2 LCD with 8051 microcontroller. Many guys find it hard to interface LCD module with the 8051 but the fact is that if you learn it properly, its a very easy job and by knowing it you can easily design embedded projects like digital voltmeter / ammeter, digital clock, home automation displays, status indicator display, digital code locks, digital speedometer/ odometer,...
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3 Great Books to Learn 555 Timer Circuits and Projects

jojo February 17, 2014 9 Comments
Any one who is interested in electronics would have come across this IC – 555. It is the one component that is used in many wide range of applications. 555 Timer is used in a variety of applications including monostable and astable multivibrators, dc-dc converters, digital logic probes, waveform generators, analog frequency meters and tachometers, temperature measurement and control devices, voltage regulators etc. So it is essential that you should have a deeper understanding of 555 IC and how it is used in these applications.  The best way...
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Indian ISP Reliance and Airtel blocks Torrentz Dailymotion Vimeo and many other websites

jojo June 5, 2012 5 Comments
The Indian ISP’s (Internet service providers) like Reliance and Airtel blocks many popular websites like (and many torrents file sharing websites), video sharing sites like Dailymotion, Vimeo and many other popular, useful websites. When you try to access these websites from an Airtel connection – it reports “Access to this site has been blocked as per Court Orders”. But in fact this “blocking” is based on an order from Telecom department of India as per the TheNextWeb report....
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8 channel light chaser using 8051

admin June 5, 2012 10 Comments
6 function 8 channel light chaser using 8051. A 6 function 8 channel light chaser using 8051 is shown here. The hardware and software of this circuit are very simple and the light functions gets repeated one after another  automatically. P1.0 to P1.7  of the microcontroller (AT89S51) are assigned as the output pins. Corresponding LEDs are connected to the output pins through 1K current limiting resistors (R1 to R8). The sequence by which the output pins (P1.0 to P1.7)...
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Blinking LED using 8051

admin June 5, 2012 6 Comments
Blinking 1 LED using 8051 This is the first project regarding 8051 and of course one of the simplest, blinking LED using 8051. The microcontroller used here is AT89S51 In the circuit, push button switch S1, capacitor C3 and resistor R3 forms the reset circuitry. When S1 is pressed, voltage at the reset pin (pin9) goes high and this resets the chip. C1, C2 and X1 are related to the on chip oscillator which produces the required clock frequency....
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4 Books to Learn 8051 Microcontroller

jojo March 25, 2014 10 Comments
Hello friends, it has been a while since I published here. This article is for students and hobbyists who are interested in playing with microcontrollers. I thought of introducing you to a handful of cool and really useful books on 8051 micro controller. The books suggested have been provided with links to shopping sites to buy from USA, India and UK. #1  8051 Microcontroller-Internals,Instructions,Programming & Interfacing by Subrata Ghoshal Many of the students out there who already know about...
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Push pull amplifier

admin May 2, 2012 23 Comments
A push pull amplifier is an amplifier which has an output stage that can drive a current in either direction through through the load. The output stage of a typical push pull amplifier consists of of two identical BJTs or MOSFETs one sourcing current through the load while the other one sinking the current from the load. Push pull amplifiers are superior over single ended amplifiers (using a single transistor at the output for driving the load) in terms...
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Working with MPLAB IDE

Anish June 5, 2012 No Comments
Introduction to MPLAB IDE – What is it and how to install it? The above link takes you to the article about introduction to MPLAB IDE, in case if you have missed it. Having installed MPLAB IDE and one or more compiler suite, this article describes how to compile a program and extract the .hex file to program our chip. I will be using C language in this tutorial as it is requested by one of our CT readers...
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What is Real Time Operating System (RTOS)- How it works?

Mathew Kevin July 10, 2017 7 Comments
                When we hear the word “Operating System” the first ones that come to our mind are those we experience/use in our day to day life, say, Windows XP, Linux, Ubuntu, Windows 7 for Computer systems, Android for mobiles and many more . We mainly know that operating systems are for computers. It is a fact that most of the digital electronic devices run some sort of operating systems inside. There are many operating systems developed for micro controllers...
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Introduction to MPLAB IDE

Anish June 5, 2012 No Comments
Similar to Atmel’s AVR studio, Microchip MPLAB is a feature rich IDE which integrates compiler tool-chains into the IDE itself and also supports proprietary programming devices and debuggers for the Microchip’s Controller family. Just if you have a microchip programmer such as Pickit2 or ICD2, then just plug it to the computer and all you need is to prepare your code in the MPLAB IDE and then straight away build and download the code into your controller. Downloading MPLAB...
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4 Great Books to Learn Basic Electronics

jojo June 14, 2016 86 Comments
For the last 3 years or so, we have been providing great educational content on electronics for free through this website. We have hundreds of circuits and theoretical articles on various topics which you can freely use to learn. But “Electronics” is a vast and wide subject and there are plenty of areas that aren’t even touched yet. We get lots of requests from readers in the form of comments and e-mails asking – How can I start learning...
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Frequency counter circuit

Mathew Kevin July 10, 2017 1 Comment
Simple Frequency Counter You may have already seen various projects over many websites named Frequency counter, Digital Frequency Counter etc. I’m posting just another of them. Showing the use of timer/counter of AVR micro controller (Atmega8) in one of it’s form. This circuit can be used as a simple micro controller project for your engineering courses. Frequency of a periodic signal is the number of cycles it repeats per second!   So If we count the number of cycles recorded...
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Standard Library & String Formatting for AVR

Mathew Kevin July 10, 2017 4 Comments
Here in this article, I am planning to brief you through the Standard library of AVR-GCC. By the term “Standard Library” we mean the “Standard header” files like “stdio.h”, we commonly see in C programming language. Have you ever used String Formatting in ANSI C? Did you use Standard library functions? If you are familiar with C programming language, then you must be familiar with standard header files we write in the beginning of the program like “#include stdio.h“,...
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