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PIC Architecture

PIC Architecture. PIC Architecture. Will now look at another architecture Look at the microcontroller company Step 1 – The programmers model. Philosophy of PIC Architecture. Embedded processing is pervasive Electronic intelligence in is everyday products Company Philosophy

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PIC Architecture

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  1. PIC Architecture Lecture 21 -PIC Architecture

  2. PIC Architecture • Will now look at another architecture • Look at the microcontroller company • Step 1 – The programmers model Lecture 21 -PIC Architecture

  3. Philosophy of PIC Architecture • Embedded processing is pervasive • Electronic intelligence in is everyday products • Company Philosophy • Have products that fit the problem • Many systems can be automated using 8-bit microcontrollers • Much of product line is 8-bit Lecture 21 -PIC Architecture

  4. 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 Lecture 21 -PIC Architecture

  5. 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 Lecture 21 -PIC Architecture

  6. Some typical applications • Automotive air bag systems • Remote control • Handheld tools • Appliances – coffee pot, mixer, stove, refrigerator, dish washer, washer, dryer • Major home systems – heating and cooling • Cordless phones and cell phones • Security systems • TV, DVD player/recorder, DVR, PVR • Sound system Lecture 21 -PIC Architecture

  7. 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 Lecture 21 -PIC Architecture

  8. 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 Lecture 21 -PIC Architecture

  9. Automotive today continued • Up to fifty 8-bit microcontrollers for functions of • Wiper control • Electric Mirrors • Air Bags • Fuel pump • Speedometer • Security system • Climate control system • Power windows ….. Lecture 21 -PIC Architecture

  10. Microchip’s position Lecture 21 -PIC Architecture

  11. Microchip and microcontroller use Lecture 21 -PIC Architecture

  12. Microcontroller choice parameters • Number of I/O pins • Amount of program and data memory • Speed • Timer Resources • Interrupt control • Robustness • Error recovery – watchdog timers • Power, I/O expansion, math support Lecture 21 -PIC Architecture

  13. Block Diagram Lecture 21 -PIC Architecture

  14. PIC architecture is a “Harvard” architecture • The Harvard Architecture Lecture 21 -PIC Architecture

  15. Feature of Harvard architecture • Near all instructions are single instruction word instructions • Only one fetch per instruction • Instruction fetch and execute are pipelined so you can operate at near clock rate instructions per second • 2 separate buses • One for instructions and one for data Lecture 21 -PIC Architecture

  16. PIC Instruction pipelining • What % of time does 1st flow of execution occur?? Lecture 21 -PIC Architecture

  17. 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. Lecture 21 -PIC Architecture

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