Category Archives: Microcontroller : 8051

Microcontroller : 8051

Posted on by
Reply

Microcontrollers : 8051

  • A highly integrated chip that contains all the components comprising a controller.
  • Typically this includes a CPU, RAM, some form of ROM, I/O ports, and timers.
  • Unlike a general-purpose computer, which also includes all of these components, a microcontroller is designed for a very specific task
    • To control a particular system.
    • Cuts down on production costs.
      • Microcontrollers are sometimes called embedded microcontrollers.

8051

  • The Intel 8051 is a Harvard architecture, single chip microcontroller (µC) which was developed by Intel in 1980 for use in embedded systems.
  • More than 20 independent manufacturers including Atmel, Infineon Technologies, Maxim Integrated Products, NXP, Nuvoton, ST Microelectronics, Silicon Laboratories, Texas Instruments and Cypress Semiconductor.
  • Intel’s official designation for the 8051 family of µCs is MCS 51.

Important features and applications

  • It provides many functions (CPU, RAM, ROM, I/O, interrupt logic, timer, etc.) in a single package
  • 8-bit ALU, Accumulator and 8-bit Registers; hence it is an 8-bit microcontroller
  • 8-bit data bus – It can access 8 bits of data in one operation
  • 16-bit address bus – It can access 216 memory locations – 64 KB (65536 locations) each of RAM and ROM
  • On-chip RAM – 128 bytes (data memory)
  • On-chip ROM – 4 kByte (program memory)
  • Four byte bi-directional input/output port
  • UART (serial port)
  • Two 16-bit Counter/timers
  • Two-level interrupt priority
  • Power saving mode

Memory Architecture

The 8051 has four distinct types of memory –

  • internal RAM
  • special function registers
  • program memory
  • external data memory

Instruction set

The 8051 instruction set offers several addressing modes, including

  • direct register, using ACC (the accumulator) and R0-R7
  • direct memory, which access the internal RAM or the SFR’s, depending on the address
  • indirect memory, using R0, R1, or DPTR to hold the memory address. The instruction used may vary to access internal RAM, external RAM, or program memory.
  • individual bits of a range of IRAM and some of the SFR’s

Related processors

The 8051’s predecessor, the 8048, was used in the keyboard of the first IBM PC, where it converted keypresses into the serial data stream which is sent to the main unit of the computer. The 8048 and derivatives are still used today[update] for basic model keyboards.

·       There are other related MCS-51 microcontrollers

o      8052

o      8032

o      8031

o      8751

And many more….