Embedded Systems

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Embedded Systems

• An embedded system is a combination of computer
  hardware and software, either fixed in capability
  or programmable, that is specifically designed
  for a particular function.
• Industrial machines, automobiles, medical
  equipment, cameras, household appliances,
  airplanes, vending machines and toys (as well as
  the more obvious cellular phone and PDA) are
  among the myriad possible hosts of an embedded
  system.

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• Physically, embedded systems range from portable
  devices such as digital watches and MP3 players,
  to large stationary installations like traffic
  lights, factory controllers, or the systems
  controlling nuclear power plants.
• Embedded systems that are programmable are
  provided with programming interfaces
  and embedded programming is a specialized
  occupation.
• It is embedded as part of a complete device often
  including hardware and mechanical parts.

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• The key characteristic is being dedicated to
  handle a particular task.
• The embedded system is dedicated to specific
  tasks, design engineers can optimize it to reduce
  the size and cost of the product and increase the
  reliability and performance. Some embedded
  systems are mass-produced, benefiting from
  economies of scale.
• Complexity varies from low, with a single
  microcontroller chip, to very high with multiple
  units, peripherals and networks mounted inside a
  large chassis or enclosure.

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Examples of Embedded Systems
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Characteristics of Embedded Systems

• An Embedded systems must have the following
  characteristics
• User Interfaces
• Simple Systems which Stem from Limited
  Functionality
• CPU Platforms with Microprocessors or
  Microcontrollers

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User Interfaces

• Originally, an embedded system had no user
  interface.
• There was no need for human interaction or
  intervention except to install the device and
  test it.
• Many modern embedded systems however, have
  full-scale user interfaces although these are
  only inputs for data but are not supposed to
  provide additional functionality for the system,
  e.g. QWERTY keyboards for PDAs used to enter
  names, addresses, phone numbers and notes and
  even full sized documents.
• The moment PDAs achieve full desktop computer
  functionalities, however, they may no longer be
  considered embedded systems.

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Simple Systems which Stem from Limited
Functionality

• This refers to basic systems such as switches,
  small character- or digit-only displays and LEDs
  intended to show the health of the embedded
  system, but this has also achieved some level of
  complexity.
• A cash register or an ATM with touch screen
  technology is considered an embedded system since
  it has limited uses, even if the user interface
  (the touch screen) is a complex system.

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CPU Platform

• Limited functionality is the key in defining
  these as embedded systems.
• In a sense, the BIOS chip is considered an
  embedded system since it has limited functions,
  and works automatically (when the computer is
  booted up).
• Peripherals like the USB can also be considered
  as embedded systems.

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Parts of Embedded Systems

• An embedded system consists of three parts
• Input
• Processing Unit
• Output
• The input device are responsible for providing
  input to the embedded system which is then
  processed by the processing unit to produce an
  desired output.

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Input Devices-sensors

• These devices provide input to the
  microcontroller.
• In general, we use sensors as input devices while
  dealing with microcontrollers.
• A sensor is a device that measures a physical
  quantity and converts it into a signal which can
  be read by an observer or by an instrument.
• The output of a sensor is an analog signal. This
  signal is utilized in analog sensors.
• Digital sensors use this signal after passing
  them from comparator IC 741 or IC LM 393. Thus,
  Digital sensors are basically a combination of
  analog sensors and comparator ICs.

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Types of sensors

• Temperature,
• Pressure,
• Level
• Humidity
• Speed
• Motion
• Distance,
• Light

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Uses of sensors

• Sensors are used in everyday objects such as
  touch-sensitive elevator buttons (tactile sensor)
  and lamps which dim or brighten by touching the
  base.
• There are also innumerable applications for
  sensors of which most people are never aware.
• Applications include cars, machines, aerospace,
  medicine, manufacturing and robotics

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Processing Unit

• These devices process the input provided by the
  input devices and produces the output.
• All the decisions are taken by this devices
  depending upon the algorithm provided by the
  user.
• The user transfers the algorithm in the form of
  program.
• Microprocessor or microcontrollers are used as
  the basic processing devices.

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Microprocessor

• A microprocessor incorporates the functions of
   computer's central processing unit (CPU) on a
  single integrated circuit (IC or microchip).
• It is a multipurpose, programmable, clock-driven,
  register-based electronic device that
  accepts digital data as input, processes it
  according to instructions stored in its memory,
  and provides results as output.
• It is an example of sequential digital logic, as
  it has internal memory, i.e. its registers.

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Microprocessors Architecture
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Microcontroller

• A digital computer having microprocessor as the
  CPU along with I/O devices and memory is known as
  microcomputer.
• The microcontroller could be called a one-chip
  solution.
• It typically includes
• CPU (central processing unit),
• RAM (Random Access Memory),
• EPROM/ PROM/ROM
• I/O (input/output)

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• By only including the features specific to the
  task (control), cost is relatively low. A typical
  microcontroller has bit manipulation
  instructions, easy and direct access to I/O
  (input/ output), and quick and efficient
  interrupt processing.
• Microcontrollers are a one-chip solution which
  drastically reduces parts count and design costs.

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Microcontrollers Architecture
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Microcontroller Vs Microprocessor

• Microcontroller
• CPU, RAM, ROM, I/O and timer are all on a single
  chip
• Fix amount of on-chip ROM, RAM, I/O ports
• For applications in which cost, power and space
  are critical
• Not versatile
• Single-purpose

• Microprocessor
• CPU is stand-alone, RAM, ROM, I/O, timer are
  separate
• Designer can decide on the amount of ROM, RAM
  and I/O ports.
• Expansive
• Versatility
• General-purpose

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Output Devices

• These devices show the result of our algorithm.
  A number of devices can be used. Some of them
  include LEDs, Motors (DC, Stepper, Servo) etc.