8051 Microcontroller

Hi this time I am sharing some information about 8051 microcontroller. Before we move to the 8051 microcontroller it’s essential for us to know, what a microcontroller is. So first of all we shall learn some thing about microcontroller.

Microcontrollers are hidden in almost every product or device with which its user can interact. In fact, any device that has a remote controller or has an LCD/LED screen and a keypad has an embedded microcontroller..

Microcontroller

The word ‘micro’ suggests that the device is small and the word ‘controller’ suggests that the device may be used to control one or more function of objects, process. It is also known as ‘embedded controller’ as they are often embedded in the device or system that they control.

8051 Microcontroller:

The Intel 8051 microcontroller is one of the most popular general purpose microcontrollers in use today. The success of the Intel 8051 spawned a number of clones which are collectively referred to as the MCS-51 family of microcontrollers.

8051 Microcontroller

The Intel 8051 is an 8-bit microcontroller which means that most available operations are limited to 8 bits. There are 3 basic "sizes" of the 8051: Short, Standard, and Extended. The Short and Standard chips are often available in DIP (dual in-line package) form, but the Extended 8051 models often have a different form factor, and are not "drop-in compatible". All these things are called 8051 because they can all be programmed using 8051 assembly language, and they all share certain features (although the different models all have their own special features).

Features of 8051microcontroller:

·         The 8051 microcontroller has a 4KB on chip memory space.

·         Internal RAM of 128 bytes.

·         Two 16-bit timers/ counter.

·         32 I/O pins.

·         Two external and three internal interrupts sources.

·         32 general purpose registers each having 8-bits.

·         16-bit program counter and data pointer.

·         8-bit stack pointer.

·         Oscillator and clock circuits.

Internal architecture and Pin diagram:

Architecture

Pin diagram

Oscillator circuit: 

The 8051 requires an external oscillator circuit. The oscillator circuit usually runs around 12MHz, although the 8051 (depending on which specific model) is capable of running at a maximum of 40MHz. Each machine cycle in the 8051 is 12 clock cycles, giving an effective cycle rate at 1MHz (for a 12MHz clock) to 3.33MHz (for the maximum 40MHz clock). The oscillator circuit generates the clock pulses so that all internal operations are synchronized.

Data and Program memory:

The 8051 Microcontroller can be programmed in PL/M, 8051 Assembly, C and a number of other high-level languages. Many compilers even have support for compiling C++ for an 8051.

Program memory in the 8051 is read-only, while the data memory is considered to be read/write accessible. When stored on EEPROM or Flash, the program memory can be rewritten when the microcontroller is in the special programmer circuit.

Special function registers:

The ‘Special Function Register’ (SFR) is the upper area of addressable memory, from address 0x80 to 0xFF. A, B, PSW, DPTR are called SFR. This area of memory cannot be used for data or program storage, but is instead a series of memory-mapped ports and registers. All port input and output can therefore be performed by memory MOV operations on specified addresses in the SFR. Also, different status registers are mapped into the SFR, for use in checking the status of the 8051, and changing some operational parameters of the 8051.

Applications of 8051 microcontrollers: 8051 chips are used in a wide variety of control systems, telecom applications, and robotics as well as in the automotive industry.

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