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Embedded System Design
Class: International graduate student
Instructor: Wei, Chao-Huang (魏兆煌)
Office: S706-3
E-Mail: [email protected]
Mobile Phone: 0930-937-932
Skype: drwei06
Course Schedule
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Hardware Design (VHDL & Schematic Entry)
Software Design (Microprocessor & C)
HW & SW Co-design
Small Real Time Operating System
Ethernet Network
Final Project
Reference Books & Webpage
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"Digital Design with CPLD Applications and VHDL", Robert K.
Dueck, Thomson.
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Any book about "C Language and 8051 Microprocessor".
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Design Entry and Synthesis Tools (Quartus II):
http://www.altera.com/products/software/quartus-ii/subscriptionedition/design-entry-synthesis/qts-des-ent-syn.html
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Embedded System Design :
http://www.cs.ucr.edu/~vahid/courses/122a_f99/index.html
Content
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What are embedded systems
History and development of embedded systems
Composition of embedded systems
Characteristic of embedded systems
Embedded system hardware development
Embedded system software development
1. What are embedded systems?
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Definition:
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Embedded system : any device that includes a
programmable computer but is not itself a generalpurpose computer.
Data processing systems except PCs and mainframe
computers.
Embedded systems are application dedicated
computing system.
A More Detailed Definition
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Embedded system are application oriented devices,
which should be optimized with hardware and software
resources. A special computing system with demand of
functionality, reliability, cost, size, and power
consumption.
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Generally, an embedded system consists of 4 parts -embedded
microprocessor,
peripheral
hardware
equipment, embedded operating system and user's
application program，used for realizing the functions ,
such as control on other equipment , monitoring or
management.
Embedding a computer
Example: Digital camera
Digital camera chip
Central processor
CCD
CCD preprocessor
Pixel coprocessor
D2A
A2D
lens
Input interface
JPEG codec
Microcontroller
Multiplier/Accum
Digital signal processor
DMA controller
Memory controller
Display ctrl
ISA bus interface
UART
LCD ctrl
Output display
Software Architecture
Application Software
Hardware
PDA: Handspring Visor
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Hardware Specs:
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Operating System: Palm OS version
3.5.2H
Processor: 33 MHz Motorola Dragonball
VZ (16-bit)
Memory: 8 MB RAM, 2M ROM
Display: 160x160 pixel, High-Res B&W,
4-bit (16 shades of gray) . Touch Panel
Battery: 2 AAA batteries
PC Connection : USB, IrDA, UART
Expansion Slot: PCMCIA
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High-End Embedded System
Examples
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Personal digital assistant (PDA).
Printer.
Cell phone.
Automobile: engine, brakes, air condition, etc.
Audio Video Recorder/Player.
Household appliances.
PC Keyboard/Mouse.
Reference Interpretation (1)
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An "embedded system" is any computer system or
computing device that performs a dedicated function
or is designed for use with a specific embedded
software application.
Embedded systems may use a ROM-based operating
system or they may use a disk-based system, like a
PC. But an embedded system is not usable as a
commercially viable substitute for general purpose
computers or devices.
Reference Interpretation (2)
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A specialized computer system that is part of a larger
system or machine. Typically, an embedded system is
housed on a single microprocessor board with the
programs stored in ROM. Virtually all appliances that
have a digital interface -- watches, microwaves,
VCRs, cars -- utilize embedded systems. Some
embedded systems include an operating system, but
many are so specialized that the entire logic can be
implemented as a single program.
Reference Interpretation(3)
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The embedded system can be divided into chip,
board, and system level.
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System on chip － Processor including the procedure
or the algorithm in one chip.
System on board － board contains some core module.
System on system － in main computing system.
1.2 History and development of
embedded systems
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First microprocessors was presented in 1971, it
marks the beginning of the embedded system.
View history of embedded systems from 4 respects:
 Hardware
 Software
 Products
 System architecture
History of embedded hardware
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1971: Intel 4004, 4-bit microprocessor
TI, TMS1000, 4-bit microcontroller
 ROM, RAM, CPU + I/O port
1980: Intel MCS-51, 8microcontroller
16-bit, 32-bit microprocessor …
1990’s, DSP
 TMS320C30
Classification and term of the
embedded processor (1)
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Micro-Controller Unit (MCU)
 i.e. Single chip. The early processor that integrated the whole
computer in a chip, the inside has a certain processor unit as
the core, and program in ROM. Some essential peripheral
hardware such as RAM, bus, bus logic, timer / counter, I/O,
serial port, A/D, D/A converter, etc. are also integrated.
 Intel 8051
Micro-Processor Unit (MPU)
 The MPU must be assembled with other essential peripheral
hardware together on a circuit board to carry out the
embedded function.
 ARM series，MIPS
Classification and term of the
embedded processor (2)
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Digital Signal Processor (DSP)
 The system structure and instructions are special
designed, that makes it suited to carrying out high
speed digital signal processing algorithm.
 TI TMS320C30
-> System-on-Chip (SoC)
 Mix the important processor kernel and various
peripheral together on a chip, can reduce the
consumption power and chip size further.
 Intel PCA architecture: PXA 255
Microprocessor varieties
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Microcontroller: includes I/O devices, on-board
memory.
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Digital signal processor (DSP): microprocessor
optimized for digital signal processing.
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Typical embedded word sizes: 8-bit, 16-bit, 32-bit.
History of embedded software
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Procedure control and monitoring
Operating system
 1981, Embedded real time kernel VTRX32
 1990’s, QNX-4
 pSOS, VxWorks, Palm OS, WinCE, Embedded
Linux, LynxOS, uCOS, Nucleus…
Architecture develops of
embedded system
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Hardware system
 Software system
 4-bit single chip
 Real-time control/
monitoring procedure
 8-bit/ 16-bit single chip
 Dedicate system
 32-bit special purpose
microprocessor
 General purpose
system
 32-bit DSP
 SoC
 SoPC
IA & Embedded System
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Information Appliance
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An appliance specializing in information :
Knowledge, facts, graphics, images, video, or
sound. An information appliance is designed to
perform activity, such as music, photography, or
writing. A distinguishing feature of information
appliance is the ability to share information among
themselves. (Don Norman)
IA & Embedded System (cont’d)
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The core of the IA machine is an embedded system
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The cost of a IA machine is depends on cost of
embedded system
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The usability of a IA machine is depends on
software of embedded system
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The development of the IA machine is followed
with the trend of embedded system
1.4 Basic construction of an
embedded system
Software
Input
I/O
Processor
Storage
I/O
Output
Fundamental hardware
software elements
Hardware
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Embedded processor
Memory/Storage
Circuits and power
supply
Interface controller
and connector
and
Software
 Real time operating
system (RTOS)
 Board Support
Package（BSP）
 Device Driver
 Protocol Stack
 Application programs
Typical embedded system hardware
architecture
Chip Board Circuit
Power
Supply
CPU Core
Interrupt
Controler
Prescaler
Oscillation
Circuit
Timer
Reset
Circuit
CPU
BCU
DMA
Ports
I/O Port
A/D
Connecting
SRAM
Connecting
DRAM
Connecting
Flash
Connecting
ROM
Connection for Debugging
External Devices
USB
LCD
Pen
Keyboard
IRDA
Others
Small Web enabled embedded
system
Typical embedded system
software architecture (VxWorks)
Hardware Independent Software
Software tools,application programs
TCP/IP
VxWorks Libraries
I/O System
Wind kernel
File System
Hardware dependent Software
BSP
Network Driver
SCSI Driver
Hardware
Ethernet
Controller
Serial
Controller
Clock
Timer
SCSI
Controller
Embedded Operating System
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Where to use
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Multi-Task
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Convenient user's interface
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Network function
Upgrade and advance development
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Basic functions of operating system
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Scheduling of multi-task
Memory management
Hardware resource management
Embedded Linux
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Basic components:
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Boot loader
Linux kernel
Further:
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Hardware drivers
Application programs
File systems based on ROM or RAM
TCP/IP stack
GUI
Real-time operation
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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.
Experiment board of this course
Microprocessor
8051 family
UART
to PC
Programable
Logic chip
Expansion Connectors
Non-functional requirements
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Many embedded systems are mass-market items that
must have low manufacturing costs.
 Limited memory, microprocessor power, etc.
Power consumption is critical in battery-powered
devices.
 Excessive power consumption increases system
cost even in wall-powered devices.
Design teams
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Often designed by a small team of designers.
Often must meet tight deadlines.
 6 month market window is common.
 Can’t miss back-to-school window for calculator.
1.6 Embedded system software
development
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Programming Languages
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Assemble, C, Java…
Cross compiler
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A kind program, which compiles the execution code
of target machine on another host machine.
Procedure of development
C/Assemble
Source Code
.obj File
Library
OS kernel
Cross Compiler
Linker
Device Driver
Debug
System Image
File
Reset &
Download
Target Board
Download and Debugging of
execution code
Development
Platform
Download execution code
Return debug
information
Target
Platform
Debugging method of embedded
systems
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LED
Simulator
ICE (In-Circuit Emulator)
Embedded ICE based on Jtag interface
Logic analyzer
Simulator
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Simulator
 A Software based on host computer totally, Simulate
functions and instructions of target machine.
Characteristic
 Simple and executable
 Lack online function debug and real-time emulation
 Can imitate the target processor only, it is unable to
imitate the function about I/O of the processor
 Common used as primary debugging tool.
ICE
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ICE: In-Circuit Emulator
 The tradition method for testing the printed circuit
board.
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ICE is a special device. It has special clips or connectors to
touch each pin of the specific CPU chip, and can monitor the
logic level on this CPU chip.
Because the integrated level of the IC is improving
constantly, the pin of the chip is increasing also. In addition,
the surface mount technology reduces the chip size. So, it is
ddifficult to use routine online emulation way…
Embedded ICE
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Embedded ICE: a set of debugging registers
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JTAG Interface
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IBCR (Instruction Break Control Register)
DBAR (Data Break Address Register)
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JTAG (Joint Test Action Group) has defined a standard of boundary scan,
need only 5 pins to realize the function of online emulation .
ARM architecture processors have embedded ICE unit, which
can be connected with the JTAG interface. Meanwhile, in order
to trace the function in real time, ARM processor embedded a
tracing unit implicitly that enables real time debug through a
logic analyzer.
ARM debugging system
Embedded System Design
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Top-down 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.
Levels of abstraction
requirements
specification
architecture
component
design
system
integration
Structure of this course
Not covered in this course, Embedded OS will be in next semester
Classification
processors
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of
embedded
Microprocessor (MPU)
Microcontroller (MCU)
Digital Signal Processor (DSP)
System on Chip (SoC)
Storage
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ROM
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PROM，EPROM，EEPROM
Flash ROM
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Flash ROM will be used in embedded system as boot
ROM and hard disk.
RAM
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SRAM
DRAM
1.5 Characteristic of embedded
systems
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Dedicate for special application
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Soft-/Hardware, computing and
network communication
integration
Constrain of real-time
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The embedded system is a specialpurpose system, while the PC is
for general applications.
Technology integration
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Use RTOS commonly
Constrain of power
consumption
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Usually no difference of
system software and
application software,
Software in ROM.
Small system kernel
High reliability
Resources much less then PC
Requirement of special
development tools
Not market monopoly
Characteristics of embedded
systems
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Sophisticated functionality.
Real-time operation.
Low manufacturing cost.
Low power.
Designed to tight deadlines by small teams.
Functional complexity
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Often have to run sophisticated algorithms or
multiple algorithms.
 Cell phone, laser printer.
Often provide sophisticated user interfaces.
PXA255 Architecture
IrDA
FF
UART
MMC/SD
Card
BT
UART
SPI to Touch
Screen
Touch
Screen
USB Client
LCD
Toshiba
LTM04C380
K
AC97 Codec
CS4201
PXA250
Application processor
Compact
Flash
USB Host
controller
SDRAM
Driver and
Transceiver
Audio Jack
Power
System
Flash
Memory
Ethernet
Controller
Boot ROM
Expansioncard slot
CPLD & Board
level Registers
Debug Leds
HEX-encoding
switches
Accelerometer
sensor