1. Embedded Systems: Introduction
Prof. Santanu Chaudhury
Prof. Wajeb Gharibi

2. Syllabus
Overview of Embedded Systems; Embedded System Architecture: Processor Examples - ARM, PIC, etc.; features of digital signal processor; SOC, memory sub-system, bus structure (PC-104, I2C etc.), interfacing protocols (USB, IrDA etc), peripheral interfacing; testing & debugging, power management; Embedded System Software: Program Optimization, Concurrent Programming, Real-time Scheduling and I/O management; Networked Embedded Systems: special networking protocols (CAN, Bluetooth); Applications.

3. Books
Computers as components: Principles of Embedded Computing System Design, Wayne Wolf, Morgan Kaufman Publication, 2000
ARM System Developer’s Guide: Designing and Optimizing System Software, Andrew N. Sloss, Dominic Symes, Chris Wright, , Morgan Kaufman Publication, 2004.
Design with PIC Microcontrollers, John B. Peatman, Pearson Education Asia, 2002
The Design of Small-Scale embedded systems, Tim Wilmshurst, Palgrave2003
Embedded System Design, Marwedel, Peter, Kluwer Publishers,

4. Definition
Embedded system: any device that includes a computer but is not itself a general-purpose computer.
Hardware and Software - part of some larger systems and expected to function without human intervention
Respond, monitor, control external environment using sensors and actuators
Typically, a embedded system will be targeted for a specific purpose and need to interact with external environments. This is the key distinguishing feature. Although some of the embedded systems can require some degree of general purpose functionality.

5. Embedding a computer Simplest model output analog input analog CPU mem
This provides a very abstract, simplified view of the embedded systems. However, interfacing with the analog outside world is a critical component.
mem
Embedded computer

6. Examples Personal digital assistant (PDA). Printer. Cell phone.
Automobile: engine, brakes, dash, etc.
Television.
Household appliances.
Surveillance Systems.

7. Product: Palm Vx handheld
Product: Palm Vx handheld. Microprocessor: 32-bit Motorola Dragonball EZ.

8. Product: Motorola i1000plus iDEN Multi-Service Digital Phone
Product: Motorola i1000plus iDEN Multi-Service Digital Phone. Microprocessor: Motorola 32-bit MCORE.

9. Application examples
Simple control: front panel of microwave oven, etc.
Camera: Canon EOS 3 has three microprocessors.
32-bit RISC CPU runs auto-focus
Analog TV: channel selection, etc.
Digital TV: Decompression, Descrambling, etc.

10. Automotive embedded systems
Today’s high-end automobile may have 100 microprocessors:
4-bit microcontroller checks seat belt;
microcontrollers run dashboard devices;
16/32-bit microprocessor controls engine.

11. Example:Automobile sensor sensor brake brake hydraulic pump
Automated Braking
System
brake
brake
sensor
sensor

12. Characteristics of embedded systems
Sophisticated functionality.
Real-time operation (always?).
Low manufacturing cost.
Application dependent Processor (?)
Restricted Memory
Low power.
Power consumption is critical in battery-powered devices.
Excessive power consumption increases system cost even in wall-powered devices.
Manufacturing cost has different components. Non-recurring Engineering cost for design and development; cost of production and marketing each unit; best technology choice will depend on the number of units we plan to produce.

13. Manufacturing Cost Manufacturing cost has different components.
Non-recurring Engineering cost for design and development;
cost of production and marketing each unit;
Best technology choice will depend on the number of units we plan to produce

14. Real-time operation Must finish operations by deadlines.
Hard real time: missing deadline causes failure.
Soft real time: missing deadline results in degraded performance.
Many systems are multi-rate: must handle operations at widely varying rates.
Operating Systems handle these components

15. Application dependent requirements
Fault-tolerance
Continue operation despite hardware or software faults
Safe
Systems to avoid physical or economic damage to person or property

16. More Features Dedicated systems
Predefined functionality – accordingly hardware and software designed
Programmability rarely used during lifetime of the system
Real-time, fault-tolerant, safe

17. More Examples

18. Product: Programmable Digital Thermostat.
Microprocessor: 4-bit

19. Product: Vending machine.
                                     
Web-enabled Cash-less Vending machine
Motient Corp. and USA Technologies
Microprocessor: 8-bit Motorola 68HC11.

20. Product: Automatic toothbrush. Microprocessor: 8-bit Zilog Z8.

21. Product: NASA's Mars Sojourner Rover. Microprocessor: 8-bit Intel 80C85.

22. Product: GPS Receiver. Microprocessor: 16-bit.

23. Product:
MP3 Player.
Microprocessor: 32-bit RISC.

24. Product:
DVD player.
Microprocessor: 32-bit RISC.

25. Product: Sony Aibo ERS-110 Robotic Dog
Product: Sony Aibo ERS-110 Robotic Dog. Microprocessor: 64-bit MIPS RISC.

26. Types of Embedded System
Similar to General Computing
PDA, Video games, Set-top boxes, automatic teller machine
Control Systems
Feed-back control of real time systems
Vehicle engines, flight control, nuclear reactors
Signal Processing
Radar, Sonar, DVD players
Communication and Networking
Cellular phones, Internet appliances

27. Nature of System Functions
Control laws
Sequencing Logic
Signal Processing
Application Specific Interfacing
Fault Response

28. More Complete Model
Architecture

29. Implementing Embedded System
Hardware
Processing Element
Peripherals
Input & Output Devices
Interfacing Sensors & Actuators
Interfacing Protocols
Memory
Bus
Software
System Software
Application
Hardware
Software
Partitioning of
tasks

30. Higher Degree of Integration
Hardware Evolution
Systems-on-Chip
Application Specific Processors
DSP
General Purpose Microprocessors & Micro-controllers
Faster Clock Rate
Higher Degree of Integration

31. Software Programs must be logically and temporally correct
Must deal with inherent physical concurrency
Reactive systems
Reliability and fault-tolerance are critical issues
Application Specific and single purpose

32. Multi-Tasking and Concurrency
Embedded systems need to deal with several inputs and outputs and multiple events occurring independently.
Separating tasks simplifies programming, but requires somehow switching back and forth among different tasks (multi-tasking).
Concurrency is the appearance of simultaneous execution of multiple tasks.

33. Example: Concurrency in Temperature Controller

34. Challenges in embedded system design
How much hardware do we need?
What is word size of the CPU? Size of Memory?
How do we meet our deadlines?
Faster hardware or cleverer software?
How do we minimize power?
Turn off unnecessary logic? Reduce memory accesses?

35. Embedded System Design

36. Design goals Performance. Functionality and user interface.
Overall speed, deadlines.
Functionality and user interface.
Manufacturing cost.
Power consumption.
Other requirements (physical size, etc.)

37. Functional vs. non-functional requirements
output as a function of input.
Non-functional requirements:
time required to compute output;
size, weight, etc.;
power consumption;
reliability;
etc.

38. Design & Development Process
requirements
specification
architecture
component
design
system
integration

39. Top-down vs. bottom-up Top-down design: Bottom-up design:
start from most abstract description;
work to most detailed.
Bottom-up design:
work from small components to big system.
Real design uses both techniques.

40. Stepwise refinement At each level of abstraction, we must:
analyze the design to determine characteristics of the current state of the design;
refine the design to add detail.

41. Concluding Remarks Embedded computers are all around us.
Many systems have complex embedded hardware and software.
Embedded systems pose many design challenges: design time, deadlines, power, etc.
Design methodologies help us manage the design process.