Microcontrollers

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Microcontrollers
Image courtesy of http//o.mneina.googlepages.com/
what_is_microcontroller.htm

• by David Gitz and Steve Warren

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What is a Microcontroller?

• What are the components of a microcontroller?
• What are the different kinds of controllers?
• What languages are used?
• How can systems be simulated?
• What kinds of applications are there?
• What resources are there?

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What is a Microcontroller?

• Lets start off by describing what a
  microcontroller is not. The term
  microcontroller denotes a completely different
  concept than microprocessor and so the two are
  not interchangeable.
• A microprocessor is a processing unit which lacks
  any memory persistence beyond its own registers
  and which must be connected to other subsystems
  to be of use in any application.
• A microcontroller is a system of electronic
  devices which always includes at least one
  microprocessor and the data structures necessary
  to persist memory across specific periods of time
  and under specific conditions. It is a
  fully-functional unit which can be programmed to
  perform specific tasks under the limits of its
  operating parameters.

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What are the Components of a Microcontroller?

• Microcontrollers are complex devices with many
  functionalities provided by different subsystems
  within the provided package. The following
  subsystems are present amongst almost all
  microcontrollers
• I/O ports/pins
• Program memory
• Data memory
• CPU (ALU Registers)
• Internal Clock Generator

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What are the Components of a Microcontroller?
(cont.)

• Some of the optional subsystems which may be
  found in a microcontroller include
• Analog-to-Digital Channels (A/D)
• Timers
• Capture/Compare Modules
• Serial Synchronous Ports
• Addressable USART
• Others

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What are the Different Kinds of Controllers?

• PIC Microcontrollers
• Parallax Propeller
• FPGA
• Including cRIO
• x86

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Comparison of Controllers

• PIC Microcontroller (C language)
• Many libraries built and for general use.
• Most commonly used.
• Usually, internal registers must be modified to
  perform various functions. (i.e. A/D, Timing,
  PWM).
• Expensive hardware usually required for
  programming. Field programming generally not
  practical.
• Very cheap (5)

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Comparison of Controllers (cont.)

• Parallax Propeller (SPIN Language)
• Multi-Core Controller
• Some good libraries built, general use
• Language is a variant of C
• Very easy to load program
• Limited memory
• Able to program in the field
• Fairly cheap (75)

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Comparison of Controllers (cont.)

• FPGA (vHDL or Verilog)
• More complicated language
• Not a whole lot of libraries available.
• Multi-thread operations
• Very applicable for digital processing
• Program Loading is fairly easy and are designed
  for programming in the field.
• Fairly cheap (100)

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Comparison of Controllers (cont.)

• cRIO FPGA (LabView)
• Has an FPGA internal. No requirement for
  programming HDL and not much requirement for
  understanding hardware constraints
• Program Loading is somewhat difficult
• Graphical Language is very easy to learn and able
  to perform very complex functions easily
• Physical Device is much larger than others
• Extensive libraries available
• Much more expensive (gt 4000)

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Comparison of Controllers (cont.)

• x86 Architecture

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What Languages Are Used?

• C/C
• Assembly (depending on processor)
• Propeller
• Propeller Assembly
• Propeller SPIN
• BASIC (for BASIC Stamp)
• FPGA
• VHDL or Verilog
• LabView

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How Can Systems Be Simulated?

• Propeller
• GEAR
• Propellent
• PIC
• MPLAB IDE
• FPGA
• Xlinx
• cRIO
• LabView
• X86
• Emu86

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What Kinds of Applications Are There?

• Data Acquisition
• Remote Monitoring
• Industrial Automation
• Automotive
• Robotics
• Image Processing

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What Resources Are There?

• Propeller/SPIN
• www.parallax.com
• cRIO/LabView
• www.ni.com/support
• FPGA
• PIC/C
• x86

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Conclusion

• Different Controllers are optimal depending on
  their intended use, although there is a large
  gray area where one is definitively better than
  the other. Usually this is decided by other
  constraints, such as what is available and the
  operating budget.

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Example Code

• LabView

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Example Code

• C

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Example Code

• SPIN

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Example Code

• x86