9/20/6Lecture 21 -PIC Architecture2 PIC Architecture Will now look at another architecture Look at the microcontroller company Step 1 – The programmers model
9/20/6Lecture 21 -PIC Architecture3 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
9/20/6Lecture 21 -PIC Architecture4 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
9/20/6Lecture 21 -PIC Architecture5 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
9/20/6Lecture 21 -PIC Architecture6 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
9/20/6Lecture 21 -PIC Architecture7 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
9/20/6Lecture 21 -PIC Architecture8 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
9/20/6Lecture 21 -PIC Architecture9 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 …..
9/20/6Lecture 21 -PIC Architecture10 Microchip’s position
9/20/6Lecture 21 -PIC Architecture11 Microchip and microcontroller use
9/20/6Lecture 21 -PIC Architecture12 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
9/20/6Lecture 21 -PIC Architecture14 PIC architecture is a “Harvard” architecture The Harvard Architecture
9/20/6Lecture 21 -PIC Architecture15 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
9/20/6Lecture 21 -PIC Architecture16 PIC Instruction pipelining What % of time does 1 st flow of execution occur??
9/20/6Lecture 21 -PIC Architecture17 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.