PIC Architecture 9206 Lecture 21 PIC Architecture 1

PIC Architecture 9/20/6 Lecture 21 -PIC Architecture 1

PIC Architecture o o o 9/20/6 Will now look at another architecture Look at the microcontroller company Step 1 – The programmers model Lecture 21 -PIC Architecture 2

Philosophy of PIC Architecture o Embedded processing is pervasive Electronic intelligence in is everyday products o Company Philosophy o n n n 9/20/6 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 3

Reasons for pervasiveness? o o o 9/20/6 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 4

Microcontroller Solution o Microcontroller features n n n 9/20/6 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 5

Some typical applications o o o o o 9/20/6 Automotive air bag systems Remote control Handheld tools Appliances – coffee pot, mixer, stove, refrigerator, dish 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 6

Come in 4 -bit through 32 -bit o 4 -bit n o 8 -bit n o 9/20/6 Still very cheap – often ~$1. 00 per chip 16 and 32 bit n o Very inexpensive Priced at $6. 00 to 12. 00 each Evaluation of requirements, chip capability, and cost come into design decision Lecture 21 -PIC Architecture 7

Typical automotive use o Engine control – 32 -bit microcontroller n o o Transmission control – 16 -bit microcontroller Audio system – 16 -bit Antilock braking – 16 -bit Up to fifty 8 -bit microcontrollers for functions of n n n 9/20/6 Fuel flow, fuel mixture, valve timing, throttle body opening, spark timing Wiper control Electric Mirrors Air Bags Lecture 21 -PIC Architecture 8

Automotive today continued o Up to fifty 8 -bit microcontrollers for functions of n n n n 9/20/6 Wiper control Electric Mirrors Air Bags Fuel pump Speedometer Security system Climate control system Power windows …. . Lecture 21 -PIC Architecture 9

Microchip’s position 9/20/6 Lecture 21 -PIC Architecture 10

Microchip and microcontroller use 9/20/6 Lecture 21 -PIC Architecture 11

Microcontroller choice parameters o o o o 9/20/6 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 12

Block Diagram 9/20/6 Lecture 21 -PIC Architecture 13

PIC architecture is a “Harvard” architecture o 9/20/6 The Harvard Architecture Lecture 21 -PIC Architecture 14

Feature of Harvard architecture o Near all instructions are single instruction word instructions n o o Instruction fetch and execute are pipelined so you can operate at near clock rate instructions per second 2 separate buses n 9/20/6 Only one fetch per instruction One for instructions and one for data Lecture 21 -PIC Architecture 15

PIC Instruction pipelining o 9/20/6 What % of time does 1 st flow of execution occur? ? Lecture 21 -PIC Architecture 16

Frequency of Branches o o o 9/20/6 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 17