ECE 4110/5110: Digital System Design

1. ECE 4110/5110: Digital System Design ECE 4110– Digital SystemDesign

2. ECE 4110– Digital System Design Lecture #1 • Agenda • Course Logistics • Course Content • Digital Review • Announcements • Welcome • Homework #1 assigned

3. Course Overview • Instructor:Omar Elkeelany • Office : 332 Brown Hall Phone : (931)-372-3450 Email : oelkeelany@tntech.edu Web : http://iweb.tntehc.edu/oelkeelany

4. Course Overview • Textbook:“Digital Design: Principles and Practices", 4th Addition John F. Wakerly, Prentice Hall, 2006 • Website:http://iweb.tntech.edu/oelkeelany/4110F13 • all handouts, homework assignments are ONLINE • it is your responsibility to download assignments

5. Course Overview • Pre-requisites:ECE2110 / ECE3160 • Grading:Homework/VHDL and Quizzes 20% Combo System project 20% Exam #1 20% Exam #2 20% Final Exam 20% - Homework Assignments are due at the beginning of class. - No Late homework will be accepted. - No make up exams will be given, unless pre-excuesd before the test. Plan on being available on the exam dates. - Term paper assignment will be given for 5110 graduate level.

6. Course Overview • Where does this course fit into the Electrical Engineering curriculum?

7. Course Overview • Where does this course fit into the Computer Engineering curriculum?

8. Course Content • What is this course?- In ECE2110 you learned: - basic combinational logic design - basic sequential logic design- In ECE3160 you learned: - how to implement logic circuits using off-the-shelf parts- ECE4110 is a follow-on course that looks at: - Large scale digital designs - Performance of digital circuitry - Programmable Logic

9. Course Content • What does "Large" mean? - Large means that you can't do it by hand. We need a way to design and simulate Millions of gates- K-maps for a Pentium would take too much paper

10. Course Content • We will learn VHDL in order to describe large digital designs - VHDL is a text based Hardware Description Language - We can simulate our digital designs created in VHDL

11. Course Content • We can also prototype our designs using an FPGA - FPGA = Field Programmable Gate Array - An FPGA is a programmable logic device - In this course, • we will implement our designs and test them in FPGA hardware

12. Course Content • What topics will be covered?1) VHDL (Exam #1 Topics) 2) Medium Scale Combinational Logic Devices 3) More Complex Finite State Machines (Exam #2 Topics) 4) Computer Systems5) FPGA Timing and Implementation • For the 5110 level, a special assignment is to: Write an original research paper on a topic related to those in this course, such as: • Modern programmable logic devices, survey, features, comparisons, usage, etc.. • Hardware description languages: survey, comparisons, usage, IP, etc. • Sequential Logic Design methods

13. Digital Review Combinational Logic Combinational Logic Gates : - Output depends on the logic value of the inputs - no storage

14. Digital Review NOT out = in’ = in f(in) = in’ = in OR out = a+b f(a,b) = a+b AND out = a·b f(a,b) = a·b

15. Digital Review XOR out = ab f(a,b) = ab NOR out = a+b f(a,b) = a+b NAND out = a·b f(a,b) = a·b

16. Digital Review XNOR out = ab f(a,b) = ab Also remember about XOR Gates: f(a,b) = ab = (a’b + b’a) Also remember the priority of logic operations (without parenthesis) is: NOT, AND, OR

17. Digital Review DeMorgan’s Theorems • Inverting the output of any gate results in the same function as the opposite gate (AND/OR) with inverted inputs

18. Digital Review DeMorgan’s Theorems • Graphically : breaking the bar changes the logic function (AND-OR) under the break out = a+b 1) Break bar out = a+b 2) Change + to · under break out = a·b

19. Digital Review Boolean Expressions Using SOP • Logic functions can be described using a Sum of Products techniques • Sum of Products (SOP) is the summation of all minterms resulting in the truth table • A minterm is the expression for an input configuration which yields a TRUE output • A minterm expression is the AND’ing of the input "1" signal configuration Truth Table about 0 0 0 0 1 1 minterm m1 = a’·b 1 0 1 minterm m2 = a·b’ 1 1 0 SOP Expression : f(a,b) = a’·b + a·b’ Note : un-minimized Boolean expression

20. Digital Review Boolean Expressions Using POS • Logic functions can be described using a Product of Sums techniques • Product of Sums (POS) is the multiplication of all maxterms resulting in the truth table • A maxterm is the expression for an input configuration which yields a FALSE output • A maxterm expression is the OR’ing of the input "0" signal configuration Truth Table about 0 0 0 maxterm m0 = a+b (input configuration of 0's) 0 1 1 1 0 1 1 1 0 maxterm m3 = a'+b' (input configuration of 0's) POS Expression : f(a,b) = (a+b) · (a'+b')

21. Digital Review Boolean Expressions Using SOP & POS • SOP and POS functions are equivalent SOP Expression : f(a,b) = a’·b + a·b’ is equal to POS Expression : f(a,b) = (a+b) · (a'+b')

22. a 0 1 b 0 1 0 1 1 1 Digital Review Karnaugh Maps • K-maps provide a graphical method to find SOP/POS expressions • K-maps also provide a graphical method to perform logic minimization K-map SOP Process 1) Circle minterms to create SOP 2) Circle in Horizontal & Vertical manner 3) Circle in groups with powers of 2 (1,2,4,8,…) Truth Table about 0 0 0 0 1 1 1 0 1 1 1 1 No dependency on b, minterm = a No dependency on a, minterm = b SOP expression : f(a,b) = a + b

23. a 0 1 b 0 1 0 1 1 1 Digital Review Karnaugh Maps • K-maps provide a graphical method to find SOP/POS expressions • K-maps also provide a graphical method to perform logic minimization K-map POS Process 1) Circle maxterms to create SOP 2) Circle in Horizontal & Vertical manner 3) Circle in groups with powers of 2 (1,2,4,8,…) Truth Table about 0 0 0 0 1 1 1 0 1 1 1 1 Dependency on a' and b', maxterm = a+b POS expression : f(a,b) = a + b

24. D Q Q Q Digital Review Sequential Logic - Concept of “Storage Element” - With Storage, logic functions can depend on current & past values of inputs - Sequential State Machines can be created D-Flip-Flop - on timing event (i.e., edge of clock input), D input goes to Q output CLK D Q tc2q

25. Digital Review State Machines - Moore : Outputs depend on present state - Mealy : Outputs depend on present state and current inputs

26. 00 01 11 10 Digital Review State Machine Example : Design a 2-bit Gray Code Counter 1) Number of States? : 4 2) Number of bits to encode states? : 2n=4, n=2 3) Moore or Mealy? : Moore For this counter, we can make the outputs be the state codes

27. 00 01 11 10 D D Q Q Q Q Digital Review State Machine Example : Design a 2-bit Gray Code Counter STATE CurrentNext Acur Bcur Anxt Bnxt 0 0 0 1 0 1 1 1 1 1 1 0 1 0 0 0 Anxt Logic Bnxt Logic Bcur0 1 Bcur0 1 Acur 0 1 Acur 0 1 0 1 1 1 0 1 0 0 Bnxt = Acur’ Anxt = Bcur A counter output B A B CLK