1 Introduction to Engineering Fall 2006 Lecture 17: Digital Tools 1

2 Review Introduction to Fault Tolerance Reliability Reliability calculations

3 Review - Primary Design Techniques Fault Avoidance Prevents faults in the first place E.g. Design review Fault Masking Localize fault, prevent error from getting into system informational structure E.g. Error correcting codes Fault Tolerant Allow the system to perform tasks in the presence of faults

4 Outline Using MatLab (again) Introduction to Digital Electronics Programmable Logic Devices

5 Using MatLab (again)

6 TMR Revisited Explore the operation of a TMR system over time using MatLab The reliability of a TMR is given by: The reliability of a single module over time is given by: So R(t) = e - t R TMR = R M + 3R M (1-R M ) = 3R M - 2R M R TMR = 3 e -2 t - 2e -3 t

7 Using MatLab Write a MatLab script to calculate the behavior of a TMR system over time

8 MatLab Run

9 Introduction to Digital Electronics

10 Digital Concept In order to design circuits, we need to understand the nature of the signals in the circuit the operation of the basic components which serve as the building blocks of the circuit

11 Voltage Levels The signals on the wires are voltages They could be any value within a given range (0 to +5 volts; 0 to + 10 volts; or -10 to +10 volts) We are only interested in the relative voltage level For example, if the range is 0 to +5 voltsvolts time 1 0 A low voltage A high voltage

12 Binary Devices Given a device with two binary inputs and one binary output, how many different operations are possible? A B C ? 2 inputs = 2 2 = 4 m = 2 inputs 2 m = 2 4 = 16 How many unique input values are there? How many unique output values are possible?

13 Possible Devices All 16 functions are shown in this table: A B A B A B C

14 Logic Gates GOAL: Select several of the possible two input devices to serve as the building blocks for other more complicated devices For example, what does device 8 do? A B A B

15 Aside: Logic Chips Logic gates like the AND are produced on an IC chip

16 Other Logic Functions Back to the issue of logic operations - what functions are implemented by: A B A B : OR3: NOT6: XOR1: NOR7: NAND

17 Logic Symbols Each of these functions has a special logic symbol: NAND AND OR XOR NOR EQU NOT

18 Physical Implementation Logic gates are constructed out of transistors The transistor was invented in 1948 In 1961, TI and Fairchild produced the first IC chip It was a dual Flip/Flop with 4 transistors It cost $50 in quantities

19 Early Efforts 1967 – Fairchild markets a semicustom chip Transistors could be easily rewired using a two layer interconnect The chip contains about 150 logic gates 1968 – Intel founded to produce memory chips By 1971 it had 500 employees By 1983 it had 21,000 employees In 1971 Intel produced the first microprocessor on a chip, 4004 It had 2300 transistors and ran at 108 Khz

20 Things are getting smaller... Thickness of skin is 100  m Finger nails grow by 1  m in 10 minutes Diameter of a piece of hair is 50  m Transistor size

21 Example – 52 Mbit SRAM Chip

22 Size Analogy Compare the complexity of ICs to city maps Assume that a city block is 100 meters on a side - then there is a 10 8 scale factor between a city and an IC chip In the 1970’s a typical IC consisted of a 2.5 mm die/10  process which maps into a 14 square mile city (Tulsa, OK) In the late 70’s a typical IC consisted of a 5 mm die/5  process which maps into a 60 square mile city (greater Chicago) In the late 80’s a typical IC consisted of a 1 cm die/1  process which maps into a map 30% larger than the state of Texas Today, a 2 cm die/0.25  process maps into a city half the size of the earth

23 Progress Comparison If the automobile industry had made the same progress as the semiconductor industry, a car would: Cost around $0.16 Be able to do 25,000 miles per hour Get 1,500 miles per gallon Seat 400,000 people

24 Physical Structure silicon Insulation wire

25 Chip Complexity Intel 8286 Intel 8486

26 Programmable Logic Devices

27 Definition DEFINITION DEFINITION: A PLD is an integrated circuit that is user configurable and capable of implementing digital logic functions It consists of a programmable array of logic gates and interconnections

28 Why PLDs? Low cost, low risk way of implementing digital circuits as application specific ICs (ASICs). Technology of choice for low to medium volume products (say hundreds to few 10’s of thousands per year). Good and low cost design software. Latest high density devices are over 1 million gates!

29 PLD Structure A programmable logic device consists of a set of AND gates and a set of OR gates. Inputs Outputs AND array OR array The inputs are split into two parts by an inverter What is the output of an AND gate with all its fused connections intact?

30 Basic FPGAs All FPGAs have the following key elements The Programming technology The basic logic cells The I/O logic cells Programmable interconnect Software to design and program the FPGA Currently the four main players in this field are:- Actel Altera Xilinx Atmel

31 FPGA FPGA building blocks: Programmable logic blocks Implement combinatorial and sequential logic Programmable interconnect Wires to connect inputs and outputs to logic blocks Programmable I/O blocks Special logic blocks at the periphery of a device used for external connections

32 Typical FPGA 4000 flip flops (you can get them with 250,000) Electrically reprogrammable Can be programmed in a number of different languages $15 (and falling) Only available in inconvenient surface mount packages

33 Altera FPGA Altera Max II

34 Possible Quiz Remember that even though each quiz is worth only 5 to 10 points, the points do add up to a significant contribution to your overall grade If there is a quiz it might cover these issues: How does an AND gate work? What is a PLD? What is an FPGA?