Introduction to Micro-Controller.

Introduction to Microcontroller
© 2018 - ToppersPedia

What is microcontroller?
• A microcontroller is a systematic microprocessor set, it consists of
microprocessor, limited amount of ROM or EPROM, RAM and I/O ports, built on
a single integrated chip.
• A microcontroller can be regarded as a microcomputer but since it performs some
specific controller functions it is called as a microcontroller.
• A microprocessor must include: full implementation of a standard
microprocessor, ROM or EPROM, RAM, parallel I/O ports, timer, a clock, serial
ports.
• A microcontroller is complicated than a microprocessor due to the presence of
several I/O components.
• For eg: Intel’s 8048, 8051.
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Advantages of microcontroller over microprocessor
based system:
• A microcontroller has more I/O components than a micro-processor based
system.
• Microprocessor-based systems are expensive while microcontroller is cheap.
• Microcontrollers have varied uses in essential products such as in PC keyboards.
Microprocessor based systems can’t be used in such products.
• Other low cost products such as electronic toys, electric drills use
microcontrollers over microprocessor-based systems.
• Daily need products such as microwave ovens, DVDs are based on
microcontrollers.

Intel’s 8051
• It has 8-bit ALU.
• It has 4K byte ROM or EPROM.
• It has 128 byte RAM.
• It has 32 I/O lines for four 8-bit I/O
ports.
• It can address 64 kB of program
memory and data memory.
• It has two external interrupts.
• It has a full featured serial port.

Intel’s 8051
• It has dual 16-bit timer event counter.
• It has powerful instruction set,
consisting of 111 instructions.
• It has a clock upto 12-MHz
frequency.
• It also has 8-bit registers (one 16-bit
register with special move
instructions), 8-bit data bus and 2×16-
bit address bus, program counter,
data pointer, and related 8/11/16-bit
operations; hence it is mainly an 8-bit
microcontroller.

Architectural Block
Diagram of 8051
• It has 32 pins for four 8-bit
bidirectional ports.
• 8 pins are provided to connect
clock crystal, timing, control
signals and power supply.
• The standard functions which
make up microcontroller are in
the mid of the diagram, it
includes ALU, accumulator,
registers, etc.
• All of the blocks are connected
to 8051 internal 8-bit data bus.
Registers hold data for I/O
transfer and control the I/O
ports.
• The diagram also includes
ROM and RAM

Memory Mapping for 8051 Microcontroller:
• It can be also regarded as addressing of
microcontroller over two separate memory
spaces.
• The 8051 addresses has two separate
memory spaces:
– Program Memory Space
– Data Memory Space
• The program memory space is read-only
memory (ROM) space.
• All instruction fetches are taken from
program memory space.

• The memory space is used for storing
programs and variable data.
• The data memory space is a read/write
memory space.
• The processor can read data from this
memory space and can write data to this
memory space.
• The 128-bytes RAM provide general
read/write data storage. Some part of this is
often regarded as registers.

• The 8051 has 22 special function registers
which are not part of the 128 bytes of
RAM. They occupy memory space from
80H to F8H.
• The 4k byte program memory can be
expanded to 64k byes. The data memory
can also be expanded.
• The 8051 can also be operated with
common memory. 8051, here, can input
data through its serial port load in memory
and execute the program.

8048 Microcontroller:
• 8048 has clock having frequency
2MHz to 4MHz.
• It has 27 I/O lines.
• It has 64 bytes RAM.
• It has one 8-bit time event counter.
• It has 1kbyte ROM or EPROM.
• It has a address capacity of 4KB.

8051 Family
8048, 8049, 8050, 8052, 8031, 8032

8048, 8049, 8050 Microcontrollers:
• 8048 was Intel’s first microcontroller.
8048-8049-8050 have almost same
architectures (differ in memory).
• 8048 supports 1K byte, 8049 supports
2K bytes of internal memory and
8050 supports 4K bytes of internal
memory.
• 8048 has 64 bytes internal RAM (w/
32 bytes of register/memory
location), 8049 has 128 bytes and 8050
has 256 bytes of RAM.
• They are very low cost, thus popular.

8052 Microcontroller
• An expansion of 8051.
• The 8052 has all the standard features
of the 8051 as well as an extra 128
bytes of RAM
• An extra timer.
• 8052 has 256 bytes of RAM and 3
timers.
• It has 8K bytes of on-chip program
ROM instead of 4K bytes.

Comparison between 8051 and 8052.
Microcontroller 8051
• It has 4k bytes of ROM.
• It has 128 bytes of RAM.
• It has a dual 16-bit timer event counter.
• Low cost.
• Point of similarity: Used in high volume
Applications and both allow us to write
large programs.
Microcontroller 8052
• It has 8k bytes of ROM.
• It has 256 bytes of RAM.
• It has an extra 16-bit timer event
counter.
• Comparatively more cost.

Applications of microcontroller:
• They are independent controllers in
machines or as slaves in distributed
processing.
• They are used as machine tools,
chemical processors, medical
instrumentation and sophisticated
guidance control.
• Keyboards use microcontrollers.
Even electronic toys and home
security system.
• It replaces scanning, debounce,
matrix decoding and serial
transmission circuits.

Introduction to Micro-Controller.

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