Microprocessors

1
Microprocessors

• For a microprocessor to give a working
  microcomputer system, which can be used for
  control tasks, additional chips are necessary,
  e.g. memory devices for program and data storage
  and input/output ports to allow it to communicate
  with the external world and receive signals from
  it.

2
Microprocessors ..

• A microcomputer, such as the IBM PC or Apple
  Macintosh incorporates a microprocessor with the
  ROM, RAM and interface circuitry requiring many
  integrated circuits and does not use
  microcontrollers.
• Microcontroller mostly found in small
  applications carrying out control-oriented
  activities. It reduces the design to the minimum
  number of components.

3
Microcontrollers

• The microcontroller is the integration of a
  microprocessor with memory and input/output
  interfaces, and other peripherals such as timers,
  on a single chip.
• Microcontroller have limited amounts ROM and RAM
  and are essentially used for the control of
  input/output devices whereas a microprocessor
  system with separate memory and input/output
  chips is more suited to processing information
  in computer systems.

4
Microcontrollers

• Microcontrollers were developed to meet a need
  for microprocessors to be put into low-cost
  products.

5
Microcontrollers

• Texas Instruments introduced the TMS-1000 4-bit
  microcontroller in mid 1970s.
• Fairchild introduced the F8, 8-bit
  microcontroller also in mid 1970s.
• Until 1978, Motorola introduced a single chip
  6800 and Intel introduced a series of products
  derived from the 8080 architecture. Both are in
  current use today

6
Microcontrollers

• Todays microcontroller is a very powerful, low
  cost and very fast. These microcontrollers often
  implemented in low-power CMOS. This lets the
  designer create low-cost battery-operated
  products.
• When compared with a system implemented with a
  stand-alone microprocessor, microcontroller
  systems often have less ROM and RAM.

7
Block Diagram of A Microcontroller
8
Basic Structure of a microcontroller

• Typically, a microcontroller has(1)
  Microprocessor (CPU)
• (2) Memory
• RAM, ROM and EPROM or EEPROM
• (3) Input/Output ports
• The pins for inputs and outputs are group into
  units called input/output ports. Usually such
  ports have eight lines in order to be able to
  transfer an 8-bit word of data.

9
Input/Output Ports ..

• Two ports may be used for a 16-bit word, one to
  transmit the lower 8 bits and the other the upper
  8 bits. The ports can be input only, output only
  or programmable as either input or output.
• Additionally, an input port might be provided
  with an analog to digital converter as that
  analog inputs can be easily handled and
  additionally one port might be for use as a
  serial port.

10
Input/Output Ports ..

• The Motorola 68HC11, Intel 8051 and PIC 16C7x are
  example of 8-bit microcontrollers, i.e. the data
  path is 8 bits wide. The Motorola 68HC16 is an
  example of a 16 bit microcontroller and the
  Motorola 68300 a 32-bit microcontroller. Family
  members differ in such features as the
  combinations of on-chip ROM or EPROM, on-chip RAM
  and timing facilities.