Embedded Systems Microcontrollers

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Embedded SystemsMicrocontrollers Embedded
ProcessorsAn Overview
In the name of God
Scientific Group of CSE Presents

• By Ramtin Raji Kermani
• Junior student of Computer Hardware Eng.
• Spring 2005

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Embedded Systems

• What is an Embedded System?
• Where are Embedded Systems used?
• Typical Embedded Systems Hardware
• Embedded OS and Software
• Microcontrollers
• The 8051 Microcontroller
• A simple project using AT89C51
• References

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What is and Embedded System?

• A specialized computer system that is part of
  a larger system or machine. Typically, an
  embedded system is housed on a single
  microprocessor board with the programs stored in
  ROM. Virtually all appliances that have a digital
  interface -- watches, microwaves, VCRs, cars --
  utilize embedded systems. Some embedded systems
  include an operating system, but many are so
  specialized that the entire logic can be
  implemented as a single program. (Definition from
  wikipedia.com)

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What is and Embedded System?
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ES, Other definitions

• A special purpose computer built into a larger
  device.
• Special purpose
• - Embedded systems have a (more or less)
  well-defined purpose
• - Contrast with general purpose computers (PCs
  etc)
• - Both hardware and software is tailored to
  application(s), which are well defined
• - However, re-programmability is a requirement
• Built into a larger device
• ESs are (usually) part of a larger device,
  augmenting its capabilities

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ES, Other definitions

• Any device that includes a programmable computer
  but is not itself a general-purpose computer.
• Anything that uses a computer but does not look
  like one.
• The microprocessor in an embedded system is like
  an electric motor in a washing machine.

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ES Types Characteristics

• Types of Processing unit
• Hardwired logic
• Programmable units
• ES Characteristics
• Efficiently
• Cost effective
• Power efficiently
• Real-time
• Predictability

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ES History and Solutions

• A very little history )
• The first Embedded System Apollo Guidance
  Computer.
• Embedded Systems Solutions
• Microcontrollers
• Embedded Processors
• Digital Signal processors

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Where are Embedded Systems used?
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Where are Embedded Systems used?

• Signal processing systems
• Real-time video, DVD players, Medical equipment.
• Distributed control
• Network routers, switches, firewalls, mass
  transit systems, Elevators
• Small systems
• Mobile phones, pagers, home appliances, toys,
  smartcards, MP3 players, PDAs, digital cameras,
  sensors, pc keyboard mouse
• Modern cars Up to 100 or more processors
• Engine control unit
• ABS systems (Anti Lock Brake systems)
• Emissions control
• Diagnostics and Security systems
• Accessories (doors, windows etc)

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Typical Embedded Systems Hardware

• Commercial off-the-shelf components (COTS)
• e.g. wireless radios, sensors, I/O devices
• Cheap
• Application-Specific ICs (ASICs)
• ICs tailored to meet application needs
• Good performance for their intended task(s)
• Original ESs were ASICs only
• Domain-specific processors
• DSPs
• Microcontrollers
• Microprocessors
• General Purpose Processors

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New trends in ES HW

• Systems-on-chip
• Usual (or desired) specs
• 32-bit RISC CPU
• Built-in interfaces to RAM and ROM
• Built-in DMA, interrupt and timing controllers
• Built-in interfaces to disk or flash memory
• Built-in Ethernet/802.11 interfaces
• Built-in LCD/CRT interfaces
• New SOCs appearing almost every week!
• Examples
• Intel StrongARM SA-1110
• Motorola PowerPC MPC823e
• NEC VR4181
• Many, many more

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Embedded OS and Software

• Principal role Not transformation of data but
  interaction with physical world
• Acquires properties of physical world
• Takes time
• Consumes power
• Does not terminate (unless it fails)

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Embedded Operating Systems

• Office-style OSes
• PalmOS
• WindowsCE
• RTOSes
• VxWorks
• QNX
• Linux
• Linux is already ubiquitous
• Hundreds of different devices are using it
• http//www.linuxdevices.com/articles/AT4936596231.
  html
• Numerous commercial open source products
• Mobile OS
• Symbian
• Others
• TinyOS

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What is a Microcontroller?

• A microcontroller is an entire computer
  manufactured on a single chip.
• They have a high concentration of on-chip
  facilities such as serial ports, parallel
  input/output ports, timers, counters, interrupt
  control, analog-to-digital converters, random
  access memory, read only memory, etc.

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The 8051 Microcontroller

• The 8051 is the first microcontroller of the
  MCS-51 family introduced by Intel Corporation at
  the end of the 1970s.
• The 8051 family characteristics
• 4K Bytes ROM
• 128 Bytes RAM
• two timer/counters (16 bit)
• A serial port
• 4 general purpose parallel input/output port
• Interrupt controller
• The 8051 can address 64K of external data
  memory and 64K of External program memory.

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Microcontroller 8051 internal Architecture
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8051 pin description

• 8051 other family members
• 8751 (has EPROM)
• 8951 (has EEPROM)

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A simple project using AT89C51

• Here weve designed, built and programmed a
  digital BCD counter that counts from 0 to 9 on a
  7Segment display.
• We use register A as Accumulator, in each delayed
  cycle the accumulator increments by one and
  result is showed on the 7segment display.

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A simple project using AT89C51
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References

• Web References
• www.google.com
• http//www.embedded.com
• http//www.wikipedia.org/wiki/Embedded_system
• http//www.linuxdevices.com
• Mani Srivastavas EE202A class
• http//nesl.ee.ucla.edu/courses/ee202a/2002f
• Edward Lee, Embedded Software
• http//citeseer.nj.nec.com/497408.html
• Books
• The 8051 Microcontroller and Embedded Systems
  Mazidi, M.A.
• Microprocessors Uffenbeck, john
• 201 ???? ???? ?? ???????????? 8051? ?. ???????
  ???????? ????

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At the End

• Thanks for your Attention )
• Ramtin Raji Kermani
• Spring 2005