1. Spring 2007 W. Rhett Davis with minor editing by J. Dean Brock UNCA ECE 406-602Slide 1 ECE 406 – Design of Complex Digital Systems Lecture 1: Introduction Spring 2007 W. Rhett Davis NC State University with significant material from Paul Franzon, Bill Allen, & Xun Liu

2. Spring 2007 W. Rhett Davis with minor editing by J. Dean Brock UNCA ECE 406-602Slide 2 Announcements l Projects are the labs » Jeremy Brown will be the TA l HW#1 Due in 12 Days

3. Spring 2007 W. Rhett Davis with minor editing by J. Dean Brock UNCA ECE 406-602Slide 3 Today’s Lecture l Introduction l Brief Review of ECE 212 l Syllabus

4. Spring 2007 W. Rhett Davis with minor editing by J. Dean Brock UNCA ECE 406-602Slide 4 ECE 406: A course in “building stuff” l Specification: Build a piece of hardware to read in 4 bits and allow the user to select one bit for output. How would you build it?

5. Spring 2007 W. Rhett Davis with minor editing by J. Dean Brock UNCA ECE 406-602Slide 5 Approaches l ECE 206/306 Approach (Software) » Microcontroller & memory on an evaluation board, assembly language or C code to implement behavior l ECE 212 Approach (Hardware) » Discrete logic chips (flip-flops, AND & OR gates, multiplexers), breadboard, wires l Which approach is better?

6. Spring 2007 W. Rhett Davis with minor editing by J. Dean Brock UNCA ECE 406-602Slide 6 Comparison of Approaches l Cost » Manufacturing / Materials (Recurring) » Design (Non-Recurring) l Performance » Speed » Power

7. Spring 2007 W. Rhett Davis with minor editing by J. Dean Brock UNCA ECE 406-602Slide 7 What are you likely to design? l Digital Still Camera (DSC) l CD Player l Satellite TV/Radio Receiver l Digital Cable Set-Top Box l Cellular Telephone l Wireless LAN Cards l HDTV Receivers l Cable Modems / DSL Modems Kodak DSC

8. Spring 2007 W. Rhett Davis with minor editing by J. Dean Brock UNCA ECE 406-602Slide 8 Kodak DSC System Overview source: http://www/ti.comhttp://www/ti.com Blue is on-chip, white is off-chip built around a TMS320DSC25 chip from Texas Instruments

9. Spring 2007 W. Rhett Davis with minor editing by J. Dean Brock UNCA ECE 406-602Slide 9 Hardware vs. Software l When to use a Hardware approach instead of a Software approach? l New Hardware is generally created whenever a micro-processor can’t be found that’s fast enough for a given application » Higher resolution camera » Higher quality video » Faster data-rate modem » 70% of embedded applications run within 250 Mhz l ECE 406 is a HARDWARE DESIGN CLASS » You’ll design an LC-3 Microcontroller before it’s over

10. Spring 2007 W. Rhett Davis with minor editing by J. Dean Brock UNCA ECE 406-602Slide 10 Review of ECE 212 l Specification: Design a piece of hardware to read in 4 bits and allow the user to select one bit for output. Block Diagram (Sketch) Schematic

11. Spring 2007 W. Rhett Davis with minor editing by J. Dean Brock UNCA ECE 406-602Slide 11 Parts of a Schematic l Ports / Terminals » interface to outside world » how many? l Nets » internal connections » how many? l Symbols » simple (or “abstract”) representation of hardware » how many? l Instances » An occurrence of a symbol » how many

12. Spring 2007 W. Rhett Davis with minor editing by J. Dean Brock UNCA ECE 406-602Slide 12 What is a Digital System? It is a organized collection of digital elements which is designed to perform specified operations on a set of digital inputs and to generate a set of digital responses. A digital system can be as simple as a block of combinational logic or as complex as a microprocessor.

13. Spring 2007 W. Rhett Davis with minor editing by J. Dean Brock UNCA ECE 406-602Slide 13 What is a Digital System? Structure of digital systems: “system” vs. “module” For small systems which can be conveniently designed monolithically the terms “system” and “module” may be used interchangeably. A digital system can be created as a monolithic structure. Complex systems often need to be partitioned into some number of subsystems -- “modules”

14. Spring 2007 W. Rhett Davis with minor editing by J. Dean Brock UNCA ECE 406-602Slide 14 What is a Digital System? Single module system: module data in control data out control System

15. Spring 2007 W. Rhett Davis with minor editing by J. Dean Brock UNCA ECE 406-602Slide 15 What is a Digital System? Multiple module system: module data in control data out control System module data in control

16. Spring 2007 W. Rhett Davis with minor editing by J. Dean Brock UNCA ECE 406-602Slide 16 Inside the TMS320DSC25 chip How do we go about designing this? Or how to computer engineers go about designing this?

17. Spring 2007 W. Rhett Davis with minor editing by J. Dean Brock UNCA ECE 406-602Slide 17 Step 1: Describe the Hardware l One approach: Simply describe the whole system as a set of schematics. l Then send your description off to a semiconductor company to fabricate for you. l What problems arise with this approach? » Drawing schematics takes too much time » How do you know for certain that it will work?

18. Spring 2007 W. Rhett Davis with minor editing by J. Dean Brock UNCA ECE 406-602Slide 18 Step 2: Simulate the Behavior l Automatically generate a timing diagram / waveforms to verify the behavior In[0] In[1] In[2] In[3] clock Out[0] Out[1] Out[2] Out[3] Clock In Out F 1 A 5 x F2AA

19. Spring 2007 W. Rhett Davis with minor editing by J. Dean Brock UNCA ECE 406-602Slide 19 Role of Hardware Description Languages l Modern digital chip and system design centers on the use of Hardware Description Languages (HDL) to capture the design at the Register Transfer Level (RTL) » RTL specifies all registers (flip-flops) and the combinational logic between the flip-flops » Capturing the design in RTL is much faster than drawing a schematic, because you don’t need to specify each gate. » But how do we get the final hardware?

20. Spring 2007 W. Rhett Davis with minor editing by J. Dean Brock UNCA ECE 406-602Slide 20 Step 3: Synthesize the Hardware l Modern design depends heavily on the use of Computer-Aided Design tools: » To synthesize the RTL design into a schematic » To turn the schematic into a chip layout, FPGA mapping or board layout » To verify the original design, and verify that the more detailed designs are consistent with the original design l Good designers depend critically on their ability to operate effectively with the CAD tools » Just knowing how to design logic is not enough » Unfortunately, you must learn a lot of tools and learn how to deal with their complexity and bugs » Its important to form a good understanding of the tool’s methodology HDLs simplify Design Capture & Design Automation

21. Spring 2007 W. Rhett Davis with minor editing by J. Dean Brock UNCA ECE 406-602Slide 21 Synthesis-based chip design l The chip is designed using synthesis tools » Used when time-to-market is the most important issue l Basic Steps: Write HDL Simulate Snythesize Place&Route Verify

22. Spring 2007 W. Rhett Davis with minor editing by J. Dean Brock UNCA ECE 406-602Slide 22 IC Design Approaches l HDL and synthesis based design is used in both Application Specific Integrated Circuits (ASICs): D-flip-flop NOR gate Place and Route Tool

23. Spring 2007 W. Rhett Davis with minor editing by J. Dean Brock UNCA ECE 406-602Slide 23 …IC Design Approaches l and Field Programmable Gate Arrays (FPGAs): Xilinx FPGA architecuture Configurable Logic Block (CLB): “cost and time-to-market pressures are forcing implementation of embedded applications to move from ASICs to FPGAs” – Tanurhan, Computer, Nov 2006

24. Spring 2007 W. Rhett Davis with minor editing by J. Dean Brock UNCA ECE 406-602Slide 24 Summary l Explain the differences between the following terms: » Schematic vs. Block Diagram » Port vs. Net » Symbol vs. Instance » System vs. Module » HDL vs. RTL