1. Introduction to Embedded Systems Introduction to Embedded Systems
Joonwon Lee
Introduction to Embedded Systems

2. Introduction to Embedded Systems
Books
Recommended Textbook:
Embedded System Design: An Introduction to Processes, Tools, and Techniques, Arnold Berger, CMP Books, ISBN #
Suggested Textbooks:
An Embedded Software Primer, David Simon
Addison-Wesley: ISBN # X
The Art of Designing Embedded Systems, Jack Ganssle
Butterworth-Heinemann: ISBN #
Embedded Systems Firmware Demystified, Ed Sutter, CMP Books, ISBN
Programming Embedded Systems in C and C ++, Michael Barr, O'Reilly,
Building Embedded Linux Systems, Karim Yaghmour, O’Reilly
Introduction to Embedded Systems

3. Why study embedded systems?
Embedded systems are key elements of our society today
An adequate supply of competent designers is a rate limiting factor in our economies ability to grow
As processing power increases, we’ll be able to do incredible things that we haven’t begun to imagine.
It is a discipline of Computer Science that has traditionally been:
Ignored
Conceded to Electrical Engineering Departments
Treated as a cast-off because of its intimacy with “hardware”
Not well understood because of its special niche
Engineers who are experienced embedded system designers are in short supply and high demand
Other countries, such as India, are filling the need
It’s a really fun topic!
Introduction to Embedded Systems

4. What is an “Embedded System”
Any device, or collection of devices, that contain one or more dedicated computers, microprocessors, or microcontrollers
Device(s) may be local - Printer, automobile, etc.
Devices may be distributed - Aircraft, ship, internet appliance
A PC or workstation may be an embedded system
Key point:
Embedded computing devices have rigidly defined operational bounds. Not general purpose computers ( PC, Unix workstation )
Introduction to Embedded Systems

5. Why are Embedded Systems Different
Dedicated to a specific task or tasks
Rich variety of microprocessors ( over 300 types )
Designs are cost-sensitive
Have real-time performance constraints
Used with Real-Time Operating Systems (RTOS)
Software failure can be life-threatening
May have constraints on power consumption
Operate over a wide-range of environmental conditions
Fewer system resources then a desktop system
All code might be stored in ROM
Require specialized design tools
May have on-chip debugging resources
Introduction to Embedded Systems

6. Characteristics of Embedded Systems
In general, there is no architectural link to standard platforms
PC ( Win9X, NT, XP, Linux), MAC, HP, Sun are considered the standard platforms
Almost every embedded design ( hardware and software ) is unique
The hardware and software are highly integrated and interdependent
ASICS, microcontrollers
Typically, have moderate to severe real-time constraints
Real-time means system must be able to respond to the outside world
May or may not have Operating System ( O/S ) services available
No printf() for debugging when there is no terminal!
Tolerance for bugs is 1000X ( or more ) lower in embedded systems then in desktop computers.
May be life-threatening consequences if system fails
Often engineered for the highest possible performance at the lowest cost
Performance may not be an important consideration
Most likely to have power constraints
Introduction to Embedded Systems

7. Let’s Define Some Terms
Microprocessor
An integrated circuit which forms the central processing unit for a computer or embedded controller, but requires additional support circuitry to function
MC68000, 80486, Pentium, K6, etc.
Microcontroller
A microprocessor plus additional peripheral support devices integrated into a single package
Peripheral support devices may include:
Serial ports ( COM ), Parallel ( Ports ), Ethernet ports, A/D & D/A
Interval timers, watchdog timers, event counter/timers, real time clock ( RTC )
Other local processors ( DSP, numeric coprocessor, peripheral controller )
ColdFIRE is a microcontroller
Introduction to Embedded Systems

8. Microprocessor and Microcontroller
A Microprocessor-Based Embedded System
A Microcontroller-Based Embedded System
Data
Storage
Program
Program
Data
Memory
Memory
Storage
I/O
Microprocessor
Microprocessor
Core
I/O
I/O
I/O
I/O
Real-time
Clock
I/O
Real-time
Clock
To outside world
To outside world
Introduction to Embedded Systems

9. A “Typical” Embedded System
Microprocessor
Address Bus
Data Bus
Status Bus
Glue Logic and
Address Decode
Clock Generation
and Distribution
Real Time Clock
Random Access
Memory - RAM
Read Only
Memory - ROM
( FLASH )
Minimally Requirement for an Embedded System
I/O Interface
( D/A, A/D, Digital )
Communications
Other
Peripheral
Devices
To Outside World
To outside world
To other devices
To host Computer
To User I/F
Watchdog Timer
NMI
Introduction to Embedded Systems

10. Common Embedded Microprocessors
4-bit Microcontrollers: PIC ($1.79)
8-bit Microprocessors and microcontrollers
Zilog: Z80 families ($1.39)
Intel: 8042, 8048, 8051 families ($4.95)
Motorola: 6805, 68HC11 families ($8.00)
16-bit Microprocessors and microcontrollers
Intel, AMD: families
Motorola: families
NEC, Hitachi, Phillips
32-bit Microprocessors and microcontrollers
Intel 80386, 80486, Pentium, PII, PIII,PIV, StrongARM, X-scale
ARM: ARM7TDMI, ARM9
AMD 486E, SC520 (Aspen)
Motorola 680X0, ColdFIRE, PowerPC
Intel X-Scale
64-bit Microprocessors and microcontrollers
MIPS family, Athlon 64
Introduction to Embedded Systems

11. “Simplified” diagram of 68HC11
Pulse Acc
PA7
PA6
PA5
PA4
PA3
PA2
PA1
PA0
ROM - 8kBytes
Timer
Port A
Periodic IRQ
RAM Bytes
Watchdog
PD5
PD4
PD2
EEPROM 512 Bytes
SPI
Port D
STRB
PE7
PE6
PE5
PE4
PE3
PE2
PE1
PE0
Port E
STRA
TxD
RxD
PD1
PD0
SCI
Port C
A/D Converter
RESET
68HC11 CPU Core
Interrupts
IRQ
Handshake I/O
Address/Data Bus
Port B
XTAL
Oscillator
Power
EXTAL
MODA
Mode
Select
MODB
5V GND
Introduction to Embedded Systems

12. Introduction to Embedded Systems
Recent developments
Moore’s Law: the complexity of integrated circuits will double every 18 months
Process technology able to put more and more functionality on the same chip as the cpu
Buzz Word: System on a Chip (SOC), or System on Silicon
ColdFIRE is designed to keep the 68K family alive!
Introduction to Embedded Systems

13. Another Example (PalmPilot)
Motorola’s Dragonball Processor
The MC68328 was chosen for Palm Pilot because it is highly integrated
Performance is underwhelming ( core )
Introduction to Embedded Systems

14. Introduction to Embedded Systems
ColdFire M5206e
variable length RISC
Denser binary code image than fixed-length RISC instructions
targeted for cost sensitive embedded market
Subset of 680X0 instruction set
Multiply/Accumulate unit for simple DSP applications
Supports 16x16 and 32x32 multiplies with 32-bit accumulate
4K Direct-mapped I-cache
8K On-chip SRAM
Lot’s of on-chip peripherals
Introduction to Embedded Systems

15. Introduction to Embedded Systems
5206e Block Diagram
Introduction to Embedded Systems

16. How do we use the on-chip peripherals?
Setting up on-chip peripheral devices on a complex microcontroller is one of the most daunting tasks for any embedded systems design engineer
Companies have created products based upon the “simple” requirement of initializing the control registers of an embedded microcontroller
Driveway from Aisys Ltd. automatically generated initialization code
Example: Program the address of the Vector Base Register (VBR)
In the 68000, the vector table is located from 0x to 0x000003FF
The ColdFire processor allows us to relocate the VBR to any 1M boundary in the address space of the processor
Assume <D0> = 0x , MOVEC D0,VBR would locate the vector table to the memory region 0x x300003FF
Introduction to Embedded Systems

17. Let’s Define Some Terms - 2
Target system
The embedded system under development
Host computer
The standard platform being used to develop the software and link to the target system for debugging
Cross-development
Using host-based tools to create a code image that will execute on a different instruction set architecture
Example:
Write a C program on your PC
Compile it to run on a PowerPC 603 using a Cross-compiler
Create a runtime image for execution in the target system
Introduction to Embedded Systems

18. Let’s Define Some Terms - 3
Time sensitive
If a task or operation does not complete in the specified amount of time, the embedded device will perform below design requirements
Example: A laser printer prints 8 pagers per minute instead of 10 ppm ( HP trumps Lexmark once again! )
Device continues to function
Time critical
If a task or operation does not complete in the specified amount of time, the embedded device will fail.
Example: Flight control system on a fly-by-wire aircraft
Device will not operate
Introduction to Embedded Systems

19. Trends in embedded systems
Processor plus ASIC
Embedded system on a board
System-on-Chip
0.35 u process technology > 106 gates
0.18 u process technology > 4x106 gates
0.12 u process technology > 9x106 gates
0.08 u process technology > 20.3x106 gates
20 million gates = 300, 68K microprocessors on one chip
Introduction to Embedded Systems

20. Embedded System - Circa 1985
8-BIT MICROPROCESSOR ( Z80 )
SOCKETED
” SPACING
DUAL IN-LINE PACKAGE ( DIP)
4 MHz CLOCK SPEED
DISCRETE LOGIC FOR “GLUE” FUNCTIONS
CRYSTAL
OSCILLATOR
EPROMS
IN SOCKETS
2K bytes
RAM
Introduction to Embedded Systems

21. Embedded System - Circa 2000
Surface Mount Components
Fine pitch I/O pins
68360 microcontroller
MHz CLOCK SPEED
Crystal Oscillator
STATIC SENSITIVE
68040, 32-BIT
MICROPROCESSOR
ASIC
RAM
FLASH
MEMORY
16 MBytes
Components on both sides
12 layer printed circuit board
Crystal
Introduction to Embedded Systems

22. Introduction to Embedded Systems

23. Introduction to Embedded Systems
Intel PXA800F Cellular processor
Introduction to Embedded Systems

24. Elements of an embedded system
Microprocessor
4, 8, 16, 32, 4 bit bus
CISC, RISC, DSP
Integrated peripherals
Debug/Test Port
Caches
Pipeline
Socketed
Multiprocessing Systems
DEBUG Port
Non-volatile memory
EPROM, FLASH, DISK
Hybrid
Volatile Memory
DRAM, SRAM
Custom Devices
ASIC’s
FPGA’s
PAL
Standard Devices
I/O Ports
Peripheral Controllers
Communication Devices
Ethernet
RS-232
SCSI
Centronics
Proprietary
Microprocessor Bus
Custom
PCI
VME
PC-102
System Clocks
RTC circuitry
System clocks
Integrated in uC
Imported/Exported
Peripheral Bus
Software
Application Code
Driver Code / BIOS
Real Time Operating System
User Interface
Communications Protocol Stacks
C, C++, Assembly Language, ADA
Legacy Code
To Outside World
Key Point: Although vastly different in complexity and design, common
architectural traits allow us to design and debug a wide variety of systems
Introduction to Embedded Systems

25. The embedded lifecycle
The Project
Pre-Prototype
Post-Prototype
H/W Design
Proto
Debug
Specification
RTOS
Integration
Sys. Test
Mfg.
S/W Design
The Integration “Loop”
Yes No
New Test?
Yes
Pass
Test?
Debug
Start
Run Test
Re-design physical h/w and/or s/w
Stop No
Introduction to Embedded Systems

26. Introduction to Embedded Systems
A tools view of the lifecycle
Literature
Compiler Tool Chain
Architectural Simulator
Evaluation Board
Customer Benchmarks
Processor Selection Phase
Enter Here
Packaged benchmarks
Past Experience
Other Similar Designs
Applications support
Instruction Set Simulator
Benchmarking tools
Design Win
Out-of-Circuit Emulation
Initial Software
Software Design Team
Logic Simulator
Logic Analyzer
Oscilloscope
Initial hardware without
working memory system
Hardware Designer(s)
ASIC
In-Circuit Emulator
Software running on
Hardware
Design Phase
In-Circuit Emulation
Logic Analyzer/Preprocessor
JTAG Emulation
ROM Emulation
MiniMON29K
SW/HW Integration Phase
Software Performance Analysis
Maintenance and upgrade of existing products
Courtesy of
Daniel Mann
Introduction to Embedded Systems

27. Common characteristics of ES
Single-functioned
Executes a single program, repeatedly
Tightly-constrained
Low cost, low power, small, fast, etc.
Reactive and real-time
Continually reacts to changes in the system’s environment
Must compute certain results in real-time without delay
Introduction to Embedded Systems

28. example -- a digital camera
Microcontroller
CCD preprocessor
Pixel coprocessor
A2D
D2A
JPEG codec
DMA controller
Memory controller
ISA bus interface
UART
LCD ctrl
Display ctrl
Multiplier/Accum
Digital camera chip
lens
CCD
Single-functioned -- always a digital camera
Tightly-constrained -- Low cost, low power, small, fast
Reactive and real-time -- only to a small extent
Introduction to Embedded Systems

29. challenge – optimizing design metrics
Obvious design goal:
Construct an implementation with desired functionality
Key design challenge:
Simultaneously optimize numerous design metrics
Design metric
A measurable feature of a system’s implementation
Optimizing design metrics is a key challenge
Introduction to Embedded Systems

30. Introduction to Embedded Systems
challenge – optimizing design metrics
Common metrics
Unit cost: the monetary cost of manufacturing each copy of the system, excluding NRE cost
NRE cost (Non-Recurring Engineering cost): The one-time monetary cost of designing the system
Size: the physical space required by the system
Performance: the execution time or throughput of the system
Power: the amount of power consumed by the system
Flexibility: the ability to change the functionality of the system without incurring heavy NRE cost
Introduction to Embedded Systems

31. Introduction to Embedded Systems
challenge – optimizing design metrics
Common metrics (continued)
Time-to-prototype: the time needed to build a working version of the system
Time-to-market: the time required to develop a system to the point that it can be released and sold to customers
Maintainability: the ability to modify the system after its initial release
Correctness, safety, many more
Introduction to Embedded Systems

32. Design metric competition -- improving one may worsen others
Expertise with both software and hardware is needed to optimize design metrics
Not just a hardware or software expert, as is common
A designer must be comfortable with various technologies in order to choose the best for a given application and constraints
Size
Performance
Power
NRE cost
Microcontroller
CCD preprocessor
Pixel coprocessor
A2D
D2A
JPEG codec
DMA controller
Memory controller
ISA bus interface
UART
LCD ctrl
Display ctrl
Multiplier/Accum
Digital camera chip
lens
CCD
Hardware
Software
Introduction to Embedded Systems

33. Time-to-market: a demanding design metric
Time required to develop a product to the point it can be sold to customers
Market window
Period during which the product would have highest sales
Average time-to-market constraint is about 8 months
Delays can be costly
Revenues ($)
Time (months)
Introduction to Embedded Systems

34. Losses due to delayed market entry
Simplified revenue model
Product life = 2W, peak at W
Time of market entry defines a triangle, representing market penetration
Triangle area equals revenue
Loss
The difference between the on-time and delayed triangle areas
On-time Delayed
entry entry
Peak revenue
Peak revenue from delayed entry
Market rise
Market fall W 2W
Time D
On-time
Delayed
Revenues ($)
Introduction to Embedded Systems

35. Losses due to delayed market entry (cont.)
Area = 1/2 * base * height
On-time = 1/2 * 2W * W
Delayed = 1/2 * (W-D+W)*(W-D)
Percentage revenue loss = (D(3W-D)/2W2)*100%
Try some examples
On-time Delayed
entry entry
Peak revenue
Peak revenue from delayed entry
Market rise
Market fall W 2W
Time D
On-time
Delayed
Revenues ($)
Lifetime 2W=52 wks, delay D=4 wks
(4*(3*26 –4)/2*26^2) = 22%
Lifetime 2W=52 wks, delay D=10 wks
(10*(3*26 –10)/2*26^2) = 50%
Delays are costly!
Introduction to Embedded Systems

36. NRE and unit cost metrics
Costs:
Unit cost: the monetary cost of manufacturing each copy of the system, excluding NRE cost
NRE cost (Non-Recurring Engineering cost): The one-time monetary cost of designing the system
total cost = NRE cost unit cost * # of units
per-product cost = total cost / # of units
= (NRE cost / # of units) + unit cost
Example
NRE=$2000, unit=$100
For 10 units
total cost = $ *$100 = $3000
per-product cost = $2000/10 + $100 = $300
Amortizing NRE cost over the units results in an additional $200 per unit
Introduction to Embedded Systems

37. NRE and unit cost metrics
Compare technologies by costs -- best depends on quantity
Technology A: NRE=$2,000, unit=$100
Technology B: NRE=$30,000, unit=$30
Technology C: NRE=$100,000, unit=$2
But, must also consider time-to-market
Introduction to Embedded Systems

38. The performance design metric
Widely-used measure of system, widely-abused
Clock frequency, instructions per second – not good measures
Digital camera example – a user cares about how fast it processes images, not clock speed or instructions per second
Latency (response time)
Time between task start and end
e.g., Camera’s A and B process images in 0.25 seconds
Throughput
Tasks per second, e.g. Camera A processes 4 images per second
Throughput can be more than latency seems to imply due to concurrency, e.g. Camera B may process 8 images per second (by capturing a new image while previous image is being stored).
Speedup of B over S = B’s performance / A’s performance
Throughput speedup = 8/4 = 2
Introduction to Embedded Systems

39. Three key embedded system technologies
Technology
A manner of accomplishing a task, especially using technical processes, methods, or knowledge
Three key technologies for embedded systems
Processor technology
IC technology
Design technology
Introduction to Embedded Systems

40. Application-specific Introduction to Embedded Systems
Processor technology
The architecture of the computation engine used to implement a system’s desired functionality
Processor does not have to be programmable
“Processor” not equal to general-purpose processor
Controller
Datapath
Controller
Datapath
Controller
Datapath
Control
logic and State register
Register
file
Control logic and State register
Registers
Control
logic
index
total
Custom
ALU
State register +
General
ALU IR PC IR PC
Data
memory
Data
memory
Program memory
Data
memory
Program memory
Assembly code for:
total = 0
for i =1 to …
Assembly code for:
total = 0
for i =1 to …
General-purpose (“software”)
Application-specific
Single-purpose (“hardware”)
Introduction to Embedded Systems

41. Introduction to Embedded Systems
Processor technology
Processors vary in their customization for the problem at hand
total = 0
for i = 1 to N loop
total += M[i]
end loop
Desired functionality
General-purpose processor
Application-specific processor
Single-purpose processor
Introduction to Embedded Systems

42. General-purpose processors
Programmable device used in a variety of applications
Also known as “microprocessor”
Features
Program memory
General datapath with large register file and general ALU
User benefits
Low time-to-market and NRE costs
High flexibility
“Pentium” the most well-known, but there are hundreds of others IR PC
Register
file
General
ALU
Datapath
Controller
Program memory
Assembly code for:
total = 0
for i =1 to …
Control
logic and State register
Data
memory
Introduction to Embedded Systems

43. Single-purpose processors
Digital circuit designed to execute exactly one program
a.k.a. coprocessor, accelerator or peripheral
Features
Contains only the components needed to execute a single program
No program memory
Benefits
Fast
Low power
Small size
Datapath
Controller
Control logic
State register
Data
memory
index
total +
Introduction to Embedded Systems

44. Application-specific processors
Programmable processor optimized for a particular class of applications having common characteristics
Compromise between general-purpose and single-purpose processors
Features
Program memory
Optimized datapath
Special functional units
Benefits
Some flexibility, good performance, size and power
Controller
Datapath
Control
logic and State register
Registers
Custom
ALU IR PC
Data
memory
Program memory
Assembly code for:
total = 0
for i =1 to …
Introduction to Embedded Systems

45. Introduction to Embedded Systems
IC technology
The manner in which a digital (gate-level) implementation is mapped onto an IC
IC: Integrated circuit, or “chip”
IC technologies differ in their customization to a design
IC’s consist of numerous layers (perhaps 10 or more)
IC technologies differ with respect to who builds each layer and when
source
drain
channel
oxide
gate
Silicon substrate
IC package IC
Introduction to Embedded Systems

46. Introduction to Embedded Systems
IC technology
Three types of IC technologies
Full-custom/VLSI
Semi-custom ASIC (gate array and standard cell)
PLD (Programmable Logic Device)
Introduction to Embedded Systems

47. Introduction to Embedded Systems
Full-custom/VLSI
All layers are optimized for an embedded system’s particular digital implementation
Placing transistors
Sizing transistors
Routing wires
Benefits
Excellent performance, small size, low power
Drawbacks
High NRE cost (e.g., $300k), long time-to-market
Introduction to Embedded Systems

48. Introduction to Embedded Systems
Semi-custom
Lower layers are fully or partially built
Designers are left with routing of wires and maybe placing some blocks
Benefits
Good performance, good size, less NRE cost than a full-custom implementation (perhaps $10k to $100k)
Drawbacks
Still require weeks to months to develop
Introduction to Embedded Systems

49. PLD (Programmable Logic Device)
All layers already exist
Designers can purchase an IC
Connections on the IC are either created or destroyed to implement desired functionality
Field-Programmable Gate Array (FPGA) very popular
Benefits
Low NRE costs, almost instant IC availability
Drawbacks
Bigger, expensive (perhaps $30 per unit), power hungry, slower
Introduction to Embedded Systems

50. Introduction to Embedded Systems
Moore’s law
The most important trend in embedded systems
Predicted in 1965 by Intel co-founder Gordon Moore
IC transistor capacity has doubled roughly every 18 months for the past several decades
10,000
1,000
100 10 1
0.1
0.01
0.001
Logic transistors per chip
(in millions)
1981
1983
1985
1987
1989
1991
1993
1995
1997
1999
2001
2003
2005
2007
2009
Note: logarithmic scale
Introduction to Embedded Systems

51. Introduction to Embedded Systems
Moore’s law
Wow
This growth rate is hard to imagine, most people underestimate
How many ancestors do you have from 20 generations ago
i.e., roughly how many people alive in the 1500’s did it take to make you?
220 = more than 1 million people
(This underestimation is the key to pyramid schemes!)
Introduction to Embedded Systems

52. Graphical illustration of Moore’s law
1981
1984
1987
1990
1993
1996
1999
2002
10,000
transistors
150,000,000
transistors
Leading edge
chip in 1981
Leading edge
chip in 2002
Something that doubles frequently grows more quickly than most people realize!
A 2002 chip can hold about 15, chips inside itself
Introduction to Embedded Systems

53. Introduction to Embedded Systems
Design Technology
The manner in which we convert our concept of desired system functionality into an implementation
Libraries/IP: Incorporates pre-designed implementation from lower abstraction level into higher level.
System
specification
Behavioral RT
Logic
To final implementation
Compilation/Synthesis: Automates exploration and insertion of implementation details for lower level.
Test/Verification: Ensures correct functionality at each level, thus reducing costly iterations between levels.
Compilation/
Synthesis
Libraries/ IP
Test/
Verification
synthesis
Behavior
Hw/Sw/ OS
Cores
components
Gates/
Cells
Model simulat./
checkers
Hw-Sw
cosimulators
HDL simulators
Gate
simulators
Introduction to Embedded Systems

54. The co-design ladder In the past: Hardware/software “codesign”
Hardware and software design technologies were very different
Recent maturation of synthesis enables a unified view of hardware and software
Hardware/software “codesign”
Implementation
Assembly instructions
Machine instructions
Register transfers
Compilers
(1960's,1970's)
Assemblers, linkers
(1950's, 1960's)
Behavioral synthesis
(1990's)
RT synthesis
(1980's, 1990's)
Logic synthesis
(1970's, 1980's)
Microprocessor plus program bits: “software”
VLSI, ASIC, or PLD implementation: “hardware”
Logic gates
Logic equations / FSM's
Sequential program code (e.g., C, VHDL)
The choice of hardware versus software for a particular function is simply a tradeoff among various design metrics, like performance, power, size, NRE cost, and especially flexibility; there is no fundamental difference between what hardware or software can implement.
Introduction to Embedded Systems

55. Independence of processor and IC technologies
Basic tradeoff
General vs. custom
With respect to processor technology or IC technology
The two technologies are independent
General-purpose
processor
ASIP
Single-
purpose
Semi-custom
PLD
Full-custom
General,
providing improved:
Customized,
Power efficiency
Performance
Size
Cost (high volume)
Flexibility
Maintainability
NRE cost
Time- to-prototype
Time-to-market
Cost (low volume)
Introduction to Embedded Systems

56. Design productivity gap
While designer productivity has grown at an impressive rate over the past decades, the rate of improvement has not kept pace with chip capacity
10,000
1,000
100 10 1
0.1
0.01
0.001
Logic transistors per chip
(in millions)
100,000
1000
Productivity
(K) Trans./Staff-Mo.
1981
1983
1985
1987
1989
1991
1993
1995
1997
1999
2001
2003
2005
2007
2009
IC capacity
productivity
Gap
Introduction to Embedded Systems

57. Design productivity gap
1981 leading edge chip required 100 designer months
10,000 transistors / 100 transistors/month
2002 leading edge chip requires 30,000 designer months
150,000,000 / transistors/month
Designer cost increase from $1M to $300M
10,000
1,000
100 10 1
0.1
0.01
0.001
Logic transistors per chip
(in millions)
100,000
1000
Productivity
(K) Trans./Staff-Mo.
1981
1983
1985
1987
1989
1991
1993
1995
1997
1999
2001
2003
2005
2007
2009
IC capacity
productivity
Gap
Introduction to Embedded Systems

58. The mythical man-month
The situation is even worse than the productivity gap indicates
In theory, adding designers to team reduces project completion time
In reality, productivity per designer decreases due to complexities of team management and communication
In the software community, known as “the mythical man-month” (Brooks 1975)
At some point, can actually lengthen project completion time! (“Too many cooks”) 10 20 30 40
10000
20000
30000
40000
50000
60000 43 24 19 16 15 18 23
Team
Individual
Months until completion
Number of designers
1M transistors, 1 designer=5000 trans/month
Each additional designer reduces for 100 trans/month
So 2 designers produce 4900 trans/month each
Introduction to Embedded Systems

59. Introduction to Embedded Systems
Summary
Embedded systems are everywhere
Key challenge: optimization of design metrics
Design metrics compete with one another
A unified view of hardware and software is necessary to improve productivity
Three key technologies
Processor: general-purpose, application-specific, single-purpose
IC: Full-custom, semi-custom, PLD
Design: Compilation/synthesis, libraries/IP, test/verification
Introduction to Embedded Systems