Understanding PIC Architecture: Philosophy, Applications, and Microcontroller Solutions, Slides of Microcomputers

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PIC Architecture

PIC Architecture

• Will now look at another architecture
• Look at the microcontroller company
• Step 1 – The programmers model

Reasons for pervasiveness?

• Competitive pressure
• Expanded functionality of products
• Provide differentiation in product from that of competitor
• Cost competitive integrated solution
• Allow creation of new classes of products

Microcontroller Solution

• Microcontroller features
  • CPU – processing unit
  • Non-volatile program memory
  • Re-settable non-volatile data memory (EEPROM)
  • RAM for data storage
  • Direct support for various input/output

Come in 4-bit through 32-bit

• 4-bit
  • Very inexpensive
• 8-bit
  • Still very cheap – often ~$1.00 per chip
• 16 and 32 bit
  • Priced at $6.00 to 12.00 each
• Evaluation of requirements, chip capability, and cost come into design decision

Typical automotive use

• Engine control – 32-bit microcontroller
  • Fuel flow, fuel mixture, valve timing, throttle body opening, spark timing
• Transmission control –16-bit microcontroller
• Audio system – 16-bit
• Antilock braking – 16-bit
• Up to fifty 8-bit microcontrollers for functions of
  • Wiper control
  • Electric Mirrors
  • Air Bags

Microchip’s position

Microchip and microcontroller use

Block Diagram

PIC architecture is a “Harvard” architecture

• The Harvard Architecture

PIC Instruction pipelining

• What % of time does 1st flow of execution occur??

Frequency of Branches

• On architectures such as the HP during the normal flow of a program’s execution on 8 to 12 instructions are executed before a branch occurs.
• (aside) Modern architectures can easily achieve above 90% correct branch prediction.
• This can be factored into actual “speed” of the processor.