Introduction to 8051 Microcontroller – Robomart India

Introduction to 8051 Microcontroller

The micro-controller has on-chip fringe devices. The 8051 is a 8-bit microcntroller planned by Intel. It was advanced for math and single Boolean operations. Its family MCS-51 incorporates 8031, 8051 and 8751 microcontrollers.12

In spite of it’s moderately , the 8051 is a standout amongst the most mainstream microcontrollers being used today. Numerous subordinate microcontrollers have subsequent to been produced that are in view of and perfect with the 8051. In this way, the capacity to program a 8051 is an essential ability for any individual who arrangements to create items that will exploit microcontrollers.

8051 is the basic microcontroller to learn Embedded sytems projects you can buy DIY Project 8051 Development board from out store.

Features of 8051

  • 4096 bytes on-chip program memory.
  • 128 bytes on-chip data memory.
  • Four register banks.
  • 128 User defined software flags.
  • Two multiple mode, 16 bit timers/counters.
  • Hardware Multiple and divide in 4µsec.
  • 64Kb each program and external RAM addressability.

Architecture of 8051

The 8051 microcontroller comprises of CPU, two sorts of memory segments, data and output ports, uncommon capacity registers and control logic required for different Peripheral functions. These components communicates with 8-bit information BUS and Bus is Buffered to the outside through an I/O port when memory is fancied.


 Pin-out of 8051

The 8051 microcontroller is bundled in a 40-pin DIP (Dual Inline Package) . Every microcontroller have data and output ports. The 8051 has 32 I/O pins arranged as four 8-bit parallel ports (P0, P1, P2, P3). Every one of the four ports are bidirectional i.e. every pin will be designed as data or output or both. Every single port pin are multiplexed with the exception of the pins of port1. Every port comprises of a hook, a output driver and an information support. The pin description is explained below:8051-pin

Port 0

Pins 32-39

Port 0 pins can be utilized as I/O pins. The output drives and information buffers of port 0 are utilized to get to outside memory. Port 0 outputs the low request byte of the outer memory address , time multiplexed with the date is being composed or read.

Port 1

Pins 1-8

Port 1 pins can be used only as Input and Output I/O pins.

Port 2

Pins 21-28

The output drives of port2 are utilized to get to outer memory. Port2 outputs the high request byte of the outside memory address when the location is 16-bits wide, generally Port2 is utilized as I/O port.


Pins 10-17

All port pins of port3 are multifunctional. They have special functions.

Power-supply pins

8051 operates on D.C power supply of +5v. The +5v is connected to the pins Vcc (pin 40) and GND is connected to the pin 20.

XTAL2 and XTAL1 Oscillator

For generating an internal clock signal, the external crystal oscillator is connected at these two pins.


ALE (Address Latch Enable)

AD0 to AD7 lines are multiplexed. To de-multiplex these lines and for obtaining lower half of an address, an external latch and ALE signal of 8051 is used.

RST (Reset)

The pin is used to reset 8051. For proper reset operation, reset signal must be held high at least for two machine cycles,when crystal oscillator is running.

PSEN (Program Store Enable)

Pin 29

It is the active low output control signal used to activate the enable signal of the external ROM/EPROM. It is activated every six oscillator periods while reading the external memory.

EA (External Access)

Pin 31

At the point when EA pin is high (joined with vcc), the system gets to address 0000H through 0FFFH are coordinated to interior ROM and project gets to addresses 1000H through FFFFH are coordinated to outside ROM/EPROM. At the point when EA is low (When 0v) all addresses (0000H to FFFFH) got by project are coordinated to the outside ROM/EPROM.

8051 Oscillator and Clock

In 8051, a machine cycle comprises of a succession of 6 states numbered S1 to S6 (12 oscillator periods). Every state is partitioned into two stages (Phase1 and Phase2). Amid Phase1, Phase1 clock is dynamic and Phase2 clock is dynamic amid Phase2. A machine cycle comprises of 12 oscillator periods, (Sate1,Phase1) to (Sate6,Phase2) of 1µsec, if the oscillator recurrence is 12MHz. Every stage goes on for one oscillator period


8051 Controller Development Board by Robomart.com8051 04-500x500

8051 Controller Board is a complete starter kit and development system for the 8051 and other AT89Sxx microcontrollers from ATMEL ® Corporation. It is designed to give designers a quick start to develop code on the 8051.

8051 Development Board kit is based on our 40 pin development board which is compatible with other Atmel AT89Sxx microcontrollers. This kit is an easy and low cost way to get started with microcontrollers. Included on board is an AT89S52 microcontroller, external crystal with supporting capacitors, AVCC filter parts, Power supply parts and more.

The AT89SXX are  low-power, high-performance CMOS 8-bit microcontrollers with Variable (4K / 8K Bytes) in-system programmable Flash memory and is compatible with the industry-standard 80C51 instruction set and pinout. The Board comes with in built 16 x 2 LCD interface and 8 Bit LEDs for quick Monitoring of digital Data at the I/O Ports. On board 8 Bit resistor Network serving as Pull Up resistor for PORT 0 of the Controller. On board there is 11.0592 MHz crystal oscillator is connected to support the throughput value of the controller. The board creates a perfect platform to use dual 16 Bit Timer-Counter with seperate Pre Scaler for AT89S51 and triple 16 Bit Timer-Counter with seperate Pre Scaler for AT89S52.
One ULN2803 IC is also available in 8051 development board to run Stepper motors. There is 1 DB-9 female connecter also mounted on board for PC connection. There is one 16 pins LCD connector(female) also available. There  are four external interrupts also available by which we can control process flow. ISP serial interface availability make use of USBASP programmer to flash program in controller. 8 keypad switch and pattern of 8 different led’s are also available on Atmega-16 board. There are  two different option to provide power supply (DC battery/adapter)to the development board. It also has 4 Interrupt switches to create interrupts.
— AT89SXX 8 Bit Microcontroller
— 16 x 2 LCD interface
— 8 Bit LED Display
— In System Programming Slot
— 3-way power supply

Kit Content:

  • 1 x 8051 Development Board with AT89S52 Controller
  • 1 x MAX232 IC
  • 1 x DS1307 IC
  • 1 x ULN2003 IC
  • 1 x 16×2 LCD (Female)
  • 1 x 8 Pin Female to Female Connecting Wire
  • 1 x 3 Pin Female to Female Connecting Wire
  • 2 x 4 Pin Female to Female Connecting Wire
  • 1 x 8051 USBASP Programmer

8051 05 A-500x500