Bài giảng Các hệ thống tin học công nghiệp - Chương 3: Introduction of Embedded Systems

Mtcn_3 1
Chapter 3
INTRODUCTION of 
EMBEDDED SYSTEMS
Mtcn_3 2
3.1. What is an Embedded System?
• Electronic devices that incorporate a 
computer (usually a microprocessor) within 
their implementation. 
• A computer is used in such devices 
primarily as a means to simplify the system 
design and to provide flexibility. 
• Often the user of the device is not even 
aware that a computer is present. 
Mtcn_3 3
Aerospace Navigation systems, automatic landing 
systems, flight attitude controls, engine 
controls, space exploration (e.g., the Mars 
Pathfinder).
Automotive Fuel injection control, passenger 
environmental controls, anti-lock braking 
systems, air bag controls, GPS mapping.
Children's 
Toys
Nintendo's "Game Boy", Mattel's "My 
Interactive Pooh", Tiger Electronic's
"Furby".
Communi-
cations
Satellites; network routers, switches, hubs.
Mtcn_3 4
Computer 
Peripherals
Printers, scanners, keyboards, displays, 
modems, hard disk drives, CD-ROM drives, 
USB Mem sticks.
Home Dishwashers, Microwave Ovens, VCRs, 
televisions, stereos, fire/security alarm 
systems, lawn sprinkler controls, 
thermostats, cameras, clock radios, 
answering machines.
Industrial Elevator controls, surveillance systems, 
robots.
Instrumen-
tation
Data collection, oscilloscopes, signal 
generators, signal analyzers, power supplies.
Mtcn_3 5
Medical Imaging systems (e.g., XRAY, MRI, and 
ultrasound), patient monitors, heart pacers.
Office 
Automation 
FAX machines, copiers, telephones, cash 
registers.
Personal Personal Digital Assistants (PDAs), pagers, 
cell phones, wrist watches, video games, 
portable MP3 players, GPS.
Mtcn_3 6
Embedded Rules!
• Embedded processors account for 100% of 
worldwide microprocessor production!
• Embedded:desktop = 100:1
• 2003: #embedded processors in the home 
estimated at 70-80.
Mtcn_3 7
Design Goal: Reliability
• Mission Critical
• Life-Threatening
• 24/7/365
• Can’t reboot!
Mtcn_3 8
Design Goal: Performance
• Multitasking and Scheduling
• Optimized I/O Î Assembly Language
• Limits, Inaccuracies of Fixed Precision
Mtcn_3 9
Design Goal: Cost
• Consumer Market: Minimize 
Manufacturing Cost.
• Fast Time to Market Required
• No chance for future modification.
Mtcn_3 10
What is a Real-Time System?
• Real-time systems process events. 
• Events occurring on external inputs cause 
other events to occur as outputs.
• Minimizing response time is usually a 
primary objective, or otherwise the entire 
system may fail to operate properly. 
Mtcn_3 11
Hard/Soft Real-Time Systems
• Soft Real-Time System
– Compute output response as fast as possible, 
but no specific deadlines that must be met.
• Hard Real-Time System
– Output response must be computed by specified 
deadline or system fails.
Mtcn_3 12
Multi-Tasking and Concurrency
• Most real-time systems are also embedded 
systems w/several inputs and outputs and 
multiple events occurring independently. 
• Separating tasks simplifies programming, 
but requires somehow switching back and 
forth among the three task (multi-tasking).
• Concurrency is the appearance of 
simultaneous execution of multiple tasks.
Mtcn_3 13
Three Concurrent Tasks Within a 
Programmable Thermostat
/* Monitor Temperature */
do forever {
measure temp ;
if (temp < setting)
start furnace ;
else if (temp >
 setting + delta)
stop furnace ;
}
/* Monitor Time of Day */
do forever {
measure time ;
if (6:00am)
setting = 72oF ;
else if (11:00pm)
setting = 60oF ;
}
/* Monitor Keypad */
do forever {
check keypad ;
if (raise temp)
setting++ ;
else if (lower temp)
setting-- ;
}
Mtcn_3 14
Programming Languages Used in 
New Embedded Designs 
0.0%
10.0%
20.0%
30.0%
40.0%
50.0%
60.0%
70.0%
80.0%
90.0%
Assembly C C++ Java Other
1998-1999
1999-2000
Mtcn_3 15
The build and load process for 
desktop application programs.
Compileril
Assemblerl
Run-Time Library:
Linker
Linker
Loader
Loader
Read-Write
Memory (RAM)
i
Operating System Image: Boot
Process
Object Files
Executable 
Image File
Mtcn_3 16
The build and load process for 
embedded application programs.
Re-Entrant Library:
Linker
Linker
Real-Time Kernel:
Locator
Locator
ROM 
"Burner"
Object 
Files
Executable 
Image File
ROM 
Image 
FileCompileril
Assemblerl
Read-Write 
Memory 
(RAM)
i
Read-Only 
Memory 
(ROM)
l
Program 
Initialization
Mtcn_3 17
Use of Real-Time Kernels in 
New Embedded Designs. 
0.0%
20.0%
40.0%
60.0%
80.0%
100.0%
4-bit 8-bit 16-bit 32-bit 64-bit Special
.
.
.
.
.
.
- it - it - it - it - it i l
Mtcn_3 18
Examples of Embedded Real-Time Software.
Property FAX Machine CD Player
Microprocessor: 16-bit 8-bit
Number of Threads: 6 9
Read-Write Memory 
(RAM): 2048 Bytes 512 Bytes
Total RAM Actually Used: 1346 Bytes (66%) 384 Bytes (75%)
Amount Used by Kernel: 250 Bytes (19%) 146 Bytes (38%)
Read-Only Memory 
(ROM): 32.0 KB 32.0 KB
Total ROM Actually Used: 28.8 KB (90%) 17.8 KB (56%)
Amount Used by Kernel: 2.5 KB (8.7%) 2.3 KB (13%)
Mtcn_3 19
Processor Types Used in New 
Embedded Designs
0.0%
10.0%
20.0%
30.0%
40.0%
50.0%
60.0%
4-bit 8-bit 16-bit 32-bit 64-bit Special
1998-1999
1999-2000
Mtcn_3 20
Product: Hunter 
Programmable Digital 
Thermostat.
Microprocessor: 4-bit
Mtcn_3 21
Product:Vendo V-
MAX 720 vending 
machine.
Microprocessor: 
8-bit Motorola 
68HC11.
Mtcn_3 22
Product: Sonicare Plus toothbrush.
Microprocessor: 8-bit Zilog Z8.
Mtcn_3 23
Product: Miele
dishwashers.
Microprocessor: 
8-bit Motorola 
68HC05.
Mtcn_3 24
Product: NASA's 
Mars Sojourner 
Rover.
Microprocessor: 
8-bit Intel 80C85.
Mtcn_3 25
Product: CoinCo
USQ-712 coin 
changer.
Microprocessor: 
8-bit Motorola 
68HC912.
Mtcn_3 26
Product: Garmin 
StreetPilot GPS 
Receiver.
Microprocessor: 
16-bit.
Mtcn_3 27
Product: TIQIT 
Computer’s 
“Matchbox PC”.
Microprocessor: 
32-bit AMD Elan
SC410.
Mtcn_3 28
Product: Palm Vx
handheld.
Microprocessor: 
32-bit Motorola 
Dragonball EZ.
Mtcn_3 29
Product: Motorola 
i1000plus iDEN Multi-
Service Digital Phone.
Microprocessor: 
Motorola 32-bit MCORE.
Mtcn_3 30
Product: Rio 800 
MP3 Player.
Microprocessor: 
32-bit RISC.
Mtcn_3 31
Product: RCA 
RC5400P DVD 
player.
Microprocessor: 
32-bit RISC.
Mtcn_3 32
Product: IBM 
Research’s Linux 
wrist watch 
prototype.
Microprocessor: 
32-bit ARM RISC.
Mtcn_3 33
Product: Sony Aibo
ERS-110 Robotic 
Dog.
Microprocessor: 
64-bit MIPS RISC.
Mtcn_3 34