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Introduction to 8051 Microcontroller

By on March 7, 2016
microcontroller 8051








With the increase of technology, we are familiar with computer, mobiles and other technology products that are playing important roles in our daily life. All these technology products have some common components e.g Processor, ROM (Read Only Memory), RAM (Random Access Memory). By contributing all these basic components an automatic system comes into existence that are used to work without the interference of human.

In basic of controllers most common and famous question is the difference between Microprocessor and Microcontroller.

Microprocessor: Microprocessor is the integrated chip based on logics. It done the functions e.g Arithmetic Logics, Digital Logics etc. But to get complete these logics it needs ROM to where from it can access the data to process and RAM to store temporary logic that are being used for a running process.

microcontroller diagram


Microcontroller: Microcontroller is the chip that have built in Processor, ROM and RAM. All these three components are embedded into single chip.

microcontroller schematic

In this article we are going to discuss 8051 family microcontrollers. Microcontrollers of this family has broad range of applications in technology and its he basic need to study 8051 family microcontrollers their programming and interfacing for starting with microcontrollers.

Actually 8051 is the subset of 8052 family. 8051 microcontrollers have half specifications than 8052 microcontrollers. Here is the comparison table of these families.

microcontroller families

At the beginning time we only need to compare the 3 basic features that are ROM, RAM and input/output ports. Since all have same ports so only remains 2 options. 8052 have double RAM and ROM compared to 8051 but 8051 are most common due to their cheap price. But the programming and interfacing of all of these is same. With the increase of ROM and RAM the processing time and storage of code size is increased.

Lets have a look on 8051 microcontroller:

microcontroller ic

8051 pinouts

As in 8051 there are 32 input/output pins. These pins are divided into ports. There are total 4 ports every port has 8 pins. VCC will connected to +5 volts and GND connected to ground.

RST (Reset) pin is used to reset the microcontroller but there need to make a reset circuitry that is show in figure bellow. XTAL1 and XTAL2 are used to connect crystal that provide the frequency to the controller. -EA/VPP pin will be connected to +5 volts.

microcontroller schematic diagram

To work properly this circuitry and the connection of +VCC and GND are necessary.

To be continued……….

hafiz Abdul Haseeb Tariq

This article was prepared for you by Hafiz Abdul Haseeb Tariq from FAST-National University of Computer and Emerging Sciences-Pakistan. He’s an Electronics & Embedded system engineer and has practical experience in circuit designing, networking, assembling, PCB making, 8051 & Arduino programming.

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  1. Albert van Bemmelen

    March 7, 2016 at 4:54 pm

    I'm glad to read more on Jestine's Blog about articles that explain the Engineering side of stuff. Like here about the 8051 CPU that easily can be programmed with the BASCOM-8051 Basic Compiler from MCS Electronics. But I myself have used their BASCOM-AVR Compiler. Because those little RISC (Reduced Instruction Set Code) AVR microcontrollers are often used in our today's Digital and Graphical Transistor LCR/ESR Testers, that Compiler did interest me more to buy the full Software Programming License for. Also usable for the Arduino controllers on which I reprogrammed an Amiga Floppy to SD copier from Polish into a great English working version.
    I wondered however why your very short intro already was devided here into a following part?

  2. Parasuraman S

    March 8, 2016 at 7:46 pm

    A deviating stream of info from our usual postings and articles! I hope you will cover uControllers used in Audio/Video Equipment and how to re-write programs, when these are no longer available from the suppliers. That is an area, I think, none has touched, and very helpful when we attempt to revive antique pieces with a bad uController IC. Replacement IC can be procured, but programs cannot be! Please keep sharing!

  3. asim

    March 10, 2016 at 11:50 pm

    nice work but i ask one question to you how we can communicate serial port diagram and tell me the free keil software for

  4. Luis Estrada

    March 12, 2016 at 4:11 am

    A very timely article on controllers. Not too long ago the question came up about a motorized shade that stopped working. I was able to determine that it was not the power source or the manual switch that actuates the motor (besides the remote control) and concluded it had to do with the controller. Searched for information on the internet as well as the shade vendor without much success. Thank you for shedding a light on the subject.

  5. reza

    March 17, 2016 at 3:14 am

    Hi mr Hafiz Abdul Haseeb Tariq
    Thank u for sharing this good Article.

  6. francis machika

    January 28, 2018 at 11:49 am

    I don't know it before.thank jestine


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