8051 Microcontroller pin Diagram and pin description

pin diagram 8051 microcontroller

In 1981, Intel introduced an 8-bit microcontroller called the 8051 microcontroller. This is one of the most popular and most commonly used microcontrollers in various fields like embedded systems, consumer electronics, automobiles, etc. Microcontroller have all features that are found in microprocessors with additional built-in ROM, RAM, I/O ports, Serial ports, Timers, Interrupts, and Clock circuits.

8051 microcontroller based on Harvard Architecture and developed primarily use in embedded  systems. Basically, 8051 microcontroller was developed by using HMOS technology, which required more power to operate. Therefore, Intel redesigned Microcontroller 8051 using CMOS technology and  their updated versions is 80C51 this required less power to operate.

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8051 MICROCONTROLLER PIN DIAGRAM

8051 microcontroller is available in 40 pin Dual Inline package (DIP). All these 40 pins perform different functions like read, write, interrupts, I/O operations, address etc. 8051 microcontroller have four I/O ports (Port-1, Port-2, Port-3, Port-4 ) where in each port has 8 pin. Each pin configured as a input pin or output pin depends on logic state of the pin. Therefore, out of 40 pins, 32 pins are allotted for I/O port. The remaining  pins are assigned to VCC, GND, XTAL1, XTAL2, RST, ALE, EA’ and PSEN’.

Now, the microcontroller 8051’s pin diagram and explanation is given below.

Pin Diagram of 8051 Microcontroller

Explanation of the Pins :

Pin 1 to Pin 8 (Port – 1) – Pin 1 to Pin 8 is assigned to Port 1 for simple I/O operations. These ports are work as a bidirectional port. It means all the pins of port 1 work as a input pin or output pins. If Logic 1 (one) is applied to the I/O port it will act as a input pin and if logic 0 (zero) is applied to the I/O port it will act as a output pin.

Pin 9 (RST) – It is a reset input Pin, which is used to reset the 8051 microcontrollers to its initial values when logic 1 is applied to this pin. It is active high pin.

Check out my you tube video for Hindi explanation of Pin Diagram of 8051 Microcontroller

Pin 10 to Pin 17 (Port-3) – Pin 10 to Pin 17 are assigned to Port 3. This port is also a bidirectional I/O port like port 1. This port performs some special functions like interrupts, control signals, timer input, serial communication etc. The detail function of each pins are given below:

  • P 10 (RXD) – Pin 10 is used as a RXD (serial data receive pin) which is for serial input pin. By using this input signal microcontroller receives data for serial communication.
  • P  11 (TXD) – Pin 11 is used as a TXD (serial data transmit pin) which is serial output pin. By using this output signal microcontroller transmits data for serial communication.
  • P 12 and P 13 (INT0′, INT1′ ) – Pins12 and 13 are used for External Hardware Interrupt 0 and Interrupt 1 respectively. When this interrupt is activated (i.e. when it is low), 8051 gets interrupted means it stopped whatever it is doing and jumps to the vector table where ISR’s (Interrupt Service Routine) are stored and starts performing Interrupt Service Routine (ISR) from that vector location.
  • P 14 and P 15 (T0 and T1) – Pin 14 and 15 are used for Timer 0 and Timer 1 external input. They can be connected with 16-bit timer/counter.
  • P 16 (WR’) – Pin 16 is used for external memory write i.e. writing data to the external memory.
  • P 17 (RD’) – Pin 17 is used for external memory read i.e. reading data from external memory.

Pin 18 and Pin 19 (XTAL2 And XTAL1) –Pins 18 and 19 i.e. XTAL 2 and XTAL 1 are the pins for interfacing external oscillator. Mostly, a Quartz Crystal Oscillator is connected here to get the system clock.

Pin 20 (GND) – Pin 20 is the Ground Pin. It is connected to the 0V (negative terminal) of the Power Supply.

Pin 21 to Pin28 (Port 2) – Pin 21 to pin 28 are port 2 pins. Port 2 is also a bidirectional Input /Output port i.e, all pins of port 2 work as a input pin or as a output pins. But, this is only possible when we are not using any external memory. If we use external memory, then these pins will work as high order address bus (A8 to A15).

Pin 29 (PSEN) – The Pin 29 is the Program Store Enable Pin (PSEN). It is used to enable external program memory and read a signal from the external program memory.

Pin 30 (ALE) – Pin 30 is the Address Latch Enable Pin. This pin is used to enable or disable the external memory interfacing.

Pin 31 (EA) – Pin 31 is the External Access Enable (EA) Pin. This pin allows external Program Memory. It is an input pin and connected from VCC or GND. If we want to access the program from external program memory, it must be connected with GND. If we want to use on-chip memory, it must be high (connected with VCC).

Pin 32 to Pin 39 (Port 0) – Pin 32 to Pin 39 are Port 0 pins. when we don’t use any external memory, these pins are used as a bidirectional pin like port 2 and port 3. But, when ALE or Pin 30 is at 1, then this port is used as data bus. And when the ALE pin is at 0, then this port is used as a lower order address bus (A0 to A7).

Pin 40 (VCC) – This pin is used to provide (+5v ) power supply to the 8051 microcontroller circuit.

Check out my you tube video for explanation of Pin Diagram of 8051 Microcontroller

FAQ’s (Frequency Asked Questions)

How many pins are there in 8051 microcontroller?

In 1981,Intel introduced an 8-bit microcontroller called the 8051 microcontroller. It is available with 40 pins DIP (dual inline package), 4kb of ROM storage and 128 bytes of RAM storage, 2 16-bit timers. It consists of are four parallel 8-bit ports, which are programmable as well as addressable as per the requirement.

What is the function of EA pin in 8051 microcontroller ?

Pin 31 is the External Access Enable (EA) Pin. This pin allows external Program Memory. It is an input pin and must be connected from VCC or GND. If we want to access the code from external program memory, it must be connected with GND. If we want to use on-chip memory, it must be high (connected with VCC).

What is the function of reset pin in microcontroller?

Pin 9 (RST) – It is a reset input Pin, which is used to reset the 8051 microcontrollers  to its initial values when logic 1 is applied to this pin. It is active high pin.

Which port is used as multifunction port?

Port 3 is multifunction part it can be used as a simple input/output port.

What happens when a high is applied to reset pin?

It is available at pin 21. When it is high, it indicates that the device is ready to transfer data. When it is low, it indicates wait state.

How many timer is 8051?

The 8051 microcontroller has two timers, Timer 0 and Timer 1. They can be used as timers or as event counters. Both Timer 0 and Timer 1 are 16-bit wide. Since the 8051 follows an 8-bit architecture, each 16 bit is accessed as two separate registers of low-byte and high-byte.

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Top 50 8051 Microcontroller MCQ – 2

Hi all, This is second part of 8051 microcontroller multiple choice questions series. In this MCQ series i have explained top 50 multiple choice questions. If you want to see more questions on 8051 microcontroller then check my previous post here.

This series will help in competitive exam like UPPCL- JE, SSC JE, RSEB, RRB and all competitive exam.

Please checkout all multiple choice questions like microcontroller, Power electronics, PLC and SCADA and 8086 microprocessor here. later I will add more questions in this series. So more update check frequently.

Question 1 Which of the following is the default value of stack once after the system undergoes the reset condition?

  • 08H
  • 09H
  • 00H
  • 07H

Answer: 07H

Question 2 Which of the following commands are used for addressing the off-chip data and associated codes respectively by data pointer?

  • MOVC & MOVY
  • MOVY & MOVB
  • MOVZ & MOVA
  • MOVX & MOVC

Answer: MOVX & MOVC

Question 3 Which of the following is the bit addressing range of addressable individual bits over the on-chip RAM?

  • 00H to 7FH
  • 01H to 7FH
  • 00H to FFH
  • 80H to FFH

Answer: 00H to 7FH

Question 4 ……….. signal control the flow of data

  • DTR
  • RTS
  • Both 1 & 2
  • None of the above

Answer: Both 1 & 2

Question 5 Register that is used to holds the memory address of the next instruction to be executed is

  • Program Memory
  • Program Counter
  • Control Unit
  • Instruction decoder

Answer: Program Counter

Question 6 If we say microcontroller is 8-bit then here 8-bit denotes size of

  • Data Bus
  • ALU
  • Control Bus
  • Address Bus

Answer: ALU

Question 7 Why microcontrollers are not called general purpose computers?

  • Because they have built in RAM and ROM
  • Because they design to perform dedicated task
  • Because they are cheap
  • Because they consume low power

Answer: Because they design to perform dedicated task

Question 8 What is the most appropriate criterion for choosing the right microcontroller of our choice?

  • Speed
  • Availability
  • Ease with the product
  • All of the mentioned

Answer: All of the mentioned

Question 9 A microcontroller at-least should consist of

  • RAM, ROM, I/O ports and timers
  • CPU, RAM, I/O ports and timers
  • CPU, RAM, ROM, I/O ports and timers
  • CPU, ROM, I/O ports and timer

Answer: CPU, RAM, ROM, I/O ports and timers

Question 10 AT89C2051 has RAM of

  • 128 bytes
  • 256 bytes
  • 64 bytes
  • 512 bytes

Answer: 128 bytes

Question 11 If we push data onto the stack then the stack pointer

  • Increases with every push
  • Decreases with every push
  • Increases & decreases with every push
  • None of the mentioned

Answer: Increases with every push

Question 12 How are the status of the carry, auxiliary carry and parity flag affected if the write instruction

MOV A,#9C

ADD A,#64H

  • CY=0,AC=0,P=0
  • CY=1,AC=1,P=0
  • CY=0,AC=1,P=0
  • CY=1,AC=1,P=1

Answer: CY=1,AC=1,P=0

Question 13 JZ, JNZ, instructions checked content of _______ register

  • DPTR
  • B
  • A
  • PSW

Answer: A

Question 14 Unlike microprocessors, microcontrollers make use of batteries because they have

  • high power dissipation
  • low power consumption
  • low voltage consumption
  • low current consumption

Answer: low power consumption

Question 15 Are PUSH and POP instructions are a type of CALL instructions?

  • yes
  • no
  • none of the mentioned
  • cant be determined

Answer: no

Question 16 What is the time taken by one machine cycle if crystal frequency is 20MHz?

  • 1.085 micro seconds
  • 0.60 micro seconds
  • 0.75 micro seconds
  • 1 micro seconds

Answer: 0.60 micro seconds

Question 17 What is the meaning of the instruction MOV A,05H?

  • Data 05H is stored in the accumulator
  • Fifth bit of accumulator is set to one
  • Address 05H is stored in the accumulator
  • None of the mentioned

Answer: Address 05H is stored in the accumulator

Question 18 The upper 128 bytes of an internal data memory from 80H through FFH usually represent _______

  • General-purpose registers
  • Special function registers
  • Stack pointers
  • Program counters

Answer: Special function registers

Question 19 Which of the ports act as the 16 bit address lines for transferring data through it?

  • PORT 0 and PORT 1
  • PORT 1 and PORT 2
  • PORT 0 and PORT 2
  • PORT 1 and PORT 3

Answer: PORT 0 and PORT 2

Question 20 Which operations are performed by the bit manipulating instructions of Boolean processor?

  • Complement bit
  • Set bit
  • Clear bit
  • All of the above

Answer: All of the above

Question 21 Which location specify the storage/loading of vector address during the interrupt generation?

  • Stack Pointer
  • Program Counter
  • Data Pointer
  • All of the above

Answer: Program Counter

Question 22 Which special function register play a vital role in the timer/counter mode selection process by allocating the bits in it?

  • TMOD
  • TCON
  • SCON
  • PCON

Answer: TMOD

Question 23 Why is it not necessary to specify the baud rate to be equal to the number of bits per second?

  • Because each bit is preceded by a start bit & followed by one stop bit
  • Because each byte is preceded by a start byte & followed by one stop byte
  • Because each byte is preceded by a start bit & followed by one stop bit
  • Because each bit is preceded by a start byte &followed by one stop byte

Answer: Because each byte is preceded by a start bit & followed by one stop bit

Question 24 Which is not the feature of 16-bit microcontroller?

  • Large program & data memory spaces
  • High speed
  • I/O Flexibility
  • Limited Control Applications

Answer: Limited Control Applications

Question 25 At what PIN number, there is EA pin which stands for External Access input?

  • PIN 28
  • PIN 29
  • PIN 30
  • PIN 31

Answer: PIN 31

Question 26 How does the microcontroller communicate with the external peripherals / memory?

  • Via I/O ports
  • Via register array
  • Via memory
  • All of the above

Answer: Via I/O ports

Question 27 What is the order decided by a processor or the CPU of a controller to execute an instruction?

  • decode, fetch, execute
  • execute, fetch, decode
  • fetch, execute, decode
  • fetch, decode, execute

Answer: fetch, decode, execute

Question 28 How are the performance and the computer capability affected by increasing its internal bus width?

  • It increases and turns better
  • It decreases
  • Remains the same
  • Internal bus width doesn’t affect the performance in any way

Answer: It increases and turns better

Question 29 How many bytes of bit addressable memory is present in 8051 based microcontrollers?

  • 8 bytes
  • 32 bytes
  • 16 bytes
  • 128 bytes

Answer: 16 bytes

Question 30 MOV A, @ R1 will:

  • Copy R1 to the accumulator
  • Copy the accumulator to R1
  • Copy the contents of memory whose address is in R1 to the accumulator
  • Copy the accumulator to the contents of memory whose address is in R1

Answer: Copy the contents of memory whose address is in R1 to the accumulator

Question 31 What is the file extension is used to load in a microcontroller to execute an instruction?

  • .doc
  • .c
  • .txt
  • .hex

Answer: .hex

Question 32 Which control signal/s is/are generated by timing and control unit of 8051 microcontroller in order to access the off-chip devices apart from the internal timings?

  • ALE
  • PSEN
  • RD & WR
  • All of the above

Answer: All of the above

Question 33 What is internal RAM memory of 8051 microprocessor?

  • 32 bytes
  • 64 bytes
  • 128 bytes
  • 256 bytes

Answer: 128 bytes

Question 34 How many timers/counter 8051 16-bit microprocessor have?

  • 1
  • 2
  • 5
  • 8

Answer: 2

Question 35 Which operator is the most important while assigning any instruction as register indirect instruction?

  • $
  • #
  • @
  • &

Answer: @

Question 36 Which of the following comes under the indexed addressing mode?

  • MOVX A, @DPTR
  • MOVC @A+DPTR,A
  • MOV A,R0
  • MOV @R0,A

Answer: MOVC @A+DPTR,A

Question 37 When we add two numbers the destination address must always be.

  • Some immediate data
  • Any register
  • Accumulator
  • Memory

Answer: Accumulator

Question 38 In 8 bit signed number operations, OV flag is set to 1 if:

  • a carry is generated from D7 bit
  • a carry is generated from D3 bit
  • a carry is generated from D7 or D3 bit
  • a carry is generated from D7 or D6 bit

Answer: a carry is generated from D7 or D6 bit

Question 39 Auto reload mode is allowed in which mode of the timer?

Mode 0
Mode 1
Mode 2
Mode 3

Answer: Mode 2

Question 40 What is the frequency of the clock that is being used as the clock source for the timer?

  • Some externally applied frequency f’
  • Controller’s crystal frequency f
  • Controller’s crystal frequency /12
  • Externally applied frequency/12

Answer: Controller’s crystal frequency /12

Question 41 Which of the following signal control the flow of data?

  • RTS
  • DTR
  • RTS & DTR
  • None of the mentioned

Answer: RTS

Question 42 Which of the following best describes the use of framing in asynchronous means of communication?

  • It binds the data properly
  • It tells us about the start and stops of the data to be transmitted or received
  • It is used for error checking
  • It is used for flow control

Answer: It tells us about the start and stops of the data to be transmitted or received

Question 43 What is the difference between UART and USART communication?

  • They are the names of the same particular thing, just the difference of A and S is there in it
  • One uses asynchronous means of communication and the other uses synchronous means of communication
  • One uses asynchronous means of communication and the other uses asynchronous and synchronous means of communication
  • One uses angular means of the communication and the other uses linear means of communication

Answer: One uses asynchronous means of communication and the other uses asynchronous and synchronous means of communication

Question 44 Which devices are specifically being used for converting serial to parallel and from parallel to serial respectively?

  • Timers
  • Counters
  • Registers
  • Serial communication

Answer: Registers

Question 45 Which pin of the external hardware is said to exhibit INT0 interrupt?

  • pin no 10
  • pin no 11
  • pin no 12
  • pin no 13

Answer: pin no 12

Question 46 Which bit of the IE register is used to enable TxD/RxD interrupt?

  • IE.D5
  • IE.D2
  • IE.D3
  • IE.D4

Answer: IE.D4

Question 47 When an interrupt is enabled, then where does the pointer moves immediately after this interrupt has occurred?

  • to the next instruction which is to be executed
  • to the first instruction of ISR
  • to a fixed location in memory called interrupt vector table
  • to the end of the program

Answer: To a fixed location in memory called interrupt vector table

Question 48 After RETI instruction is executed then the pointer will move to which location in the program?

  • next interrupt of the interrupt vector table
  • immediate next instruction where interrupt is occurred
  • next instruction after the RETI in the memory
  • none of the mentioned

Answer: To a fixed location in memory called interrupt vector table

Question 49 Which pin of the LCD is used for adjusting its contrast?

  • pin no 1
  • pin no 2
  • pin no 3
  • pin no 4

Answer: pin no 3

Question 50 For writing commands on an LCD, RS bit is

set
reset
set & reset
none of the mentioned

Answer: Reset


FAQ

What is Microcontroller?

Microcontroller is a combination of two words micro and controller, Micro means small in size and controller means a device that can control the operation of any system. So we can say that a microcontroller is a microprocessor with integrated peripherals.

What is the order decided by a processor or the CPU of a controller to execute an instruction?

First instruction is fetched from Program Memory, then fetching, instruction is decoded to generate control signals to perform the intended task. After decoding, instruction is executed and the complete intended task of that particular instruction.

How are the performance and the computer capability affected by increasing its internal bus width?

As the bus width increases, the number of bits carried by bus at a time increases as a result of which the total performance and computer capability increases.

How many bytes of bit addressable memory is present in 8051 based microcontrollers?

8051 microcontrollers have 16 bytes of bit addressable memory.

How many timers/counter 8051 microcontroller have?

8051 Microcontroller 8051 have 2 timers/counter.

When was intel design first 8051 microcontroller?

8051 microcontroller is designed by Intel in 1981. It is an 8-bit microcontroller

Why is CHMOS technology preferred over HMOS technology for designing the devices of MCS-51 family?

Micro Controllers are made by using the concept of VLSI technology. So here, CMOS based logic gates are coupled together by this technique that consumes low power.

8051 series has how many 16 bit registers?

8051 microcontroller has two 16 bit registers DPTR and PC.

8051 microcontrollers are manufactured by which of the following companies?

8051 microcontrollers are manufactured by Intel, Atmel, Philips/Signetics, Infineon, Dallas Semi/Maxim.

Which IO Port can be used for higher address byte with addresses A8-A15?

PORT2 : This port can be used for higher address byte with addresses A8-A15. When no memory is added then this port can be used as a general input/output port similar to Port 1.

Classification of 8051 Microcontroller

What is Microcontroller ?

Microcontroller is a combination of two words micro and controller, Micro means small in size and controller means a device that can control the operation of any system. So we can say that a microcontroller is a microprocessor with integrated peripherals.

  • A microcontroller is a system on chip it has CPU, I/O ports, Timers, Counters, RAM,ROM on a single chip.
  • In 1981, Intel introduced an 8-bit microcontroller called the 8051.
  • Originally, 8051 Microcontrollers were developed using N-MOS Technology but the use of battery powered devices and their low power consumption, Now a day CMOS Technology (which is famous for its low power consumption).
  • It is widely used in an embedded system, consumer electronics, automotive systems, robotics and security cameras.
  • The peripheral are integrated into a single chip , the over all system cost is very low.
  • The size of the product is small as compare to the microprocessor based system thus very handy .
  • The microcontroller based system is more reliable.
  • MC based system is easy to maintain.
  • All these features available in 40 pin IC.

Classification of Microcontroller

Classification Of Microcontroller According to the Number of Bits

According to bits the microcontroller are 8-bits, 16-bits, and 32-bits microcontroller.

  • 8 Bit Microcontroller: In 8 bit microcontroller the internal bus is 8 bit then the ALU performs arithmetic and logic operations. Example: Intel 8031/8051.
  • 16 Bit Microcontroller: In 16 bit microcontroller executes with greater accuracy and performance in contrast to 8-bit. So 16 bit microcontroller performance is greater compared to 8-bit. 8-bit microcontrollers can only use 8 bits, So its data range of 0×00 – 0xFF (0-255) for every cycle. Where as 16-bit microcontrollers with their data range of 0×0000 – 0xFFFF (0-65535) for every cycle. Example: Intel 8096.
  • 32 Bit Microcontroller: In 32 bit microcontroller uses the 32-bit instructions to carry
    out any arithmetic and logic operations. It is employed mainly in automatically controlled appliances such as office machines, implantable medical appliances, etc. Example: PIC3X

Classification Of Microcontroller According to Memory Devices

According to memory devices Microcontroller are divided into two types.

  1. External Memory Microcontroller
  2. Embedded Memory Microcontroller
  1. External Memory Microcontroller: In this type of microcontroller all functional blocks are not present on a single chip but if we want program memory then externally interfaced using an interfacing circuits and this interfacing circuit is called the glue circuit and the microcontroller is called external memory microcontroller. Example: 8031 has no program memory on the chip is an external memory microcontroller.
  2. Embedded Memory Microcontroller: In this type of microcontroller all functional blocks are present on a single chip is called an embedded microcontroller. Example: 8051 is the best example of embedded memory microcontroller because It having program & data memory, I/O ports, serial communication, counters and timers and interrupts on a single chip.

Classification Of Microcontroller According to Instruction Set

CISC (complex instruction set computer): CISC is stands for Complex Instruction Set Computer. It allows the user to apply one instruction as an alternative to many simple instructions.
RISC (Reduced Instruction Set Computers):  The RISC stands for Reduced Instruction set Computer. It reduces the operation time by shortening the clock cycle per instruction.

Classification Of Microcontroller According to Memory Architecture

According to Memory Architecture there are two type of Microcontroller

  • Harvard Memory Architecture
  • Von Neumann Memory Architecture

Harvard Memory Architecture: In Harvard architecture separate storage and signal buses are provided for different set of instructions and data. This architecture has the entire data storage within the CPU and there is no access available for instruction storage as data.

Von Neumann architecture: In Von Neumann architecture, one data path (or bus) is exists for both instruction and data. So, the CPU does only one operation at a time. It either fetches an instruction from memory, or performs read/write operation on data. So both operations (instruction fetch and a data operation) cannot occur simultaneously because they sharing a common bus.


Different Type of Microcontroller

PIC Microcontroller:

  • PIC Stands for Peripheral Interface Controller is a kind of microcontroller components was used in the development of electronics, computer robotics, and similar devices.
  • Even though the PIC was produced by Microchip technology and based on hardware computing architecture, here the code and data are placed in separate registers to increase the input and output.
  • PIC has a built-in data memory, data bus and dedicated microprocessor for preparing all I/O purposes and methods.

ARM Microcontroller

  • ARM stands for Advanced RISC Machine.
  • It’s the most popular Microcontrollers Programming in the digital embedded system world, and most of the industries prefer only ARM microcontrollers since it consists of significant features to implement products with an excellent appearance.
  • It is cost sensitive and high-performance device which has been used in a wide range of application such as Industrial Instrument control systems, wireless networking and sensors, and automotive body systems, etc.

8051 Microcontroller

In 1981, Intel introduced an 8-bit microcontroller called the 8051.
It is widely used in an embedded system, consumer electronics, automotive systems, robotics and security cameras.
The peripheral are integrated into a single chip , the over all system cost is very lo
The size of the product is small as compare to the microprocessor based system thus very handy
All these features available in 40 pin IC.

MSP Microcontroller

MSP stands for Mixed Signal Processor. It’s the family from Texas Instruments. Built around a 16 -bit CPU.
the MSP is designed for low cost and respectively, low power dissipation embedded statements.
It’s the controller’s appearance is directly related to the 16-bit data bus, and seven addressing modes and the decreased instructions set, which allows a shorter, denser programming code for fast performance.
The Range of Microcontroller is an IC chip that executes programs for controlling other device or machines. It is a micro-device which is used for control of other device machines that’s why it’s called Microcontrollers Programming.

8051 Microcontroller: Introduction, Features and Applications

8051 Microcontroller is a combination of two words micro and controller, Micro means small in size and controller means a device that can control the operation of any system. So we can say that a microcontroller is a microprocessor with integrated peripherals. Microcontrollers are mostly used in embedded systems, engineering projects.

Read more :

The 8051 Microcontroller is one of the most popular and most commonly used microcontrollers in various fields like embedded systems, consumer electronics, automobiles, etc. Microcontroller consists of all features that are found in microprocessors with additional built-in ROM, RAM, I/O ports, Serial ports, Timers, Interrupts, and Clock circuits.

Microcontroller contain combinational circuits and sequential circuits inside it. The Combinational circuits are designed with the help of logic gates to perform logical operations. The sequential circuits are designed by interconnection of combinational circuits and memory or storage elements those are counters, flip-flops, etc.

  • In 1981, Intel introduced an 8-bit microcontroller called the 8051. 
  • It was referred as system on a chip because it had CPU,RAM, On-chip ROM, timers, Counter, serial I/O port, all on a single chip.
  • Originally, 8051 Microcontrollers were developed using N-MOS Technology but the use of battery powered devices and their low power consumption, Now a day CMOS Technology (which is famous for its low power consumption).
  • It is widely used in an embedded system, consumer electronics, automotive systems, robotics and security cameras.
  • The peripheral are integrated into a single chip , the over all system cost is very low.
  • The size of the product is small as compare to the microprocessor based system thus very handy .
  • The microcontroller based system is more reliable.
  • MC based system is easy to maintain.
  • All these features available in 40 pin IC.

Features of 8051 Microcontroller

8051 microcontroller have following features −

  • 128 bytes on-chip data memory (RAM)
  • 4KB bytes on-chip program memory (ROM)
  • 128 user defined software flags
  • 8-bit data bus (bidirectional)
  • 16-bit address bus (unidirectional)
  • 32 general purpose registers each of 8-bit
  • 16 bit Timers (usually 2, but may have more or less)
  • Three internal and two external Interrupts
  • Four 8-bit ports,(short model have two 8-bit ports)
  • 16-bit program counter and data pointer
  • Four register banks
  • 8051 may also have special features like UARTs, ADC etc.

Block Diagram

Block Diagram of Microcontroller

A microcontroller is a microprocessor with integrated peripherals. So we can say that Microcontroller consists of all features that are found in microprocessors with additional built-in ROM, RAM, I/O ports, Serial ports, Timers, Interrupts, and Clock circuits.

Check out the Hindi explanation of 8051 microcontroller Introduction, Feature, and Applications


Difference between Microprocessor & Microcontroller

Difference between Microprocessor & Microcontroller

Microprocessor only have CPU in the chip like most of the Intel Processors but Microcontroller also have RAM, ROM and other peripherals along with the CPU or processor. Both ICs have different applications and have their own advantages and disadvantages. They can be differentiated in terms of Applications, structure, internal parameters, power consumption, and cost.


Applications of 8051 Microcontroller

The 8051 have wide range of applications, but it is mainly used for the embedded system. Following are some applications it is used for.

  1. Consumer Appliances
  2. Home Appliances ( Music Instruments TVs, VCR, Video Games, Oven)
  3. Communication Systems
  4. Office
  5. Automobiles
  6. Aeronautical and Space
  7. Medical Equipment
  8. Defense Systems
  9. Robotics
  10. Industrial Process and Flow Control
  11. Radio and Networking Equipment
  12. Remote Sensing

Check out the explanation of 8051 microcontroller Introduction, Feature, and Applications

 

FAQ’s (Frequently Ask Questions)

What is microcontroller?

Microcontroller is a microprocessor with integrated peripherals. Microcontrollers are mostly used in embedded systems, engineering projects. Microcontroller consists of all features that are found in microprocessors with additional built-in ROM, RAM, I/O ports, Serial ports, Timers, Interrupts, and Clock circuits.

Intel 8051 microcontroller follow which Architecture ?

Intel 8051 is based on Harvard Architecture.

What is 8051 microcontroller block diagram?

The block diagram of the 8051 Microcontroller Architecture shows that 8051 Microcontroller consists of a CPU, RAM (SFRs and Data Memory), Flash (EEPROM), I/O Ports and control logic for communication between the peripherals.

Why 8051 Is Called 8 Bit Microcontroller?

The Intel 8051 is an 8-bit microcontroller which means that most available operations are limited to 8 bits.

List Out The Features Of 8051 Microcontroller?

128 bytes on-chip data memory (RAM)
4KB bytes on-chip program memory (ROM)
128 user-defined software flags
The 8-bit data bus (bidirectional)
16-bit address bus (unidirectional)
32 general purpose registers each of 8-bit
16-bit Timers (usually 2, but may have more or less)
Three internal and two external Interrupts
Four 8-bit ports,(short model have two 8-bit ports)
16-bit program counter and data pointer
Four register banks
8051 may also have special features like UARTs, ADC, etc.

What Is The Width Of Data Bus in 8051 microcontroller?

The Width Of Data Bus in 8051 microcontroller 8-bit data bus.

What Is The Width Of Address Bus in 8051 microcontroller ?

The Width Of Address Bus in 8051 microcontroller 16-bit address bus.

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