All Arduino boards contain a microcontroller, which is a small computer. It then describes some popular Arduino boards like the Uno, Nano, Due, and Mega and their key specs and applications.

What is Embedded System?
Lecture 1
1

• General-purpose computer systems
• Embedded Systems
Computer Systems
2

Embedded System
 Embedded System is a special-purpose
computer system designed to perform
one or a few dedicated functions.
 In general, it does not provide programmability to
users, as opposed to general purpose computer
systems like PC
3

 Embedded systems are virtually everywhere in
your daily life
 A combination of hardware and software which
together form a component of a larger machine.
 An embedded system is designed to run on its
own without human intervention, and may be
required to respond to events in real time.
Embedded System
4

The
Embedded
Computer
An Embedded
System
Compressor Control
Actual Temperature
Human
Interaction
Alarm
Display
Required Temperature
Networked
Interaction
(Maybe!)
Example 1: Fridge
5

Dash
Board
Air
Bag
Radio
Climate
& CD
Door
Door
Steering
Driver's
Seat
Central
Control
CAN Bus
Control
Left
Right
Example 2: Car Door Control, within
a Larger Network
6

Embedded Systems (Cont)
• Even though embedded systems cover a wide range
of special-purpose systems, there are common
characteristics
 Low cost
• Should be cheap to be competitive
 Memory is typically very small compared to a
general purpose computer system
 Lightweight processors are used in
embedded systems
 Low power
• Should consume low power especially in case
of portable devices
7

Embedded Systems (Cont)
 High performance
• Should meet the computing requirements of
applications
 Users want to watch video on portable devices
 Real-time property
• Job should be done within a time limit
 Aerospace applications, Car control systems,
Medical gadgets are critical in terms of time
constraint – Otherwise, it could lead to
catastrophe such as loss of life
8

HW/SW Stack of Embedded Systems
 Identical to the general computer systems
Application Software
OS / Device Drivers
Hardware
9

Components of Embedded Systems
1. Hardware
It is mainly composed of processor (1 or more), memory,
I/O devices including network devices, timers, sensors etc.
10

2. Software - System software
 Operating systems
• Many times, a multitasking (multithreaded) OS is required, as
embedded applications become complicated
 Networking, GUI, Audio, Video
 CPU is context-switched to process multiple jobs
• Operating system footprint should be small enough to fit into
memory of an embedded system
 In the past and even now, real-time operating systems (RTOS)
such as VxWorks and uC/OS-II have been used because they are
light-weighted in terms of memory requirement
 Nowadays, heavy-weighted OSs such as iOS (iPhone OS), Android,
Windows Mobile, and embedded Linux (uClinux) are used, as
embedded processors support computing power and advanced
capabilities such as MMU (Memory Management Unit)
 Device drivers for I/O devices
11

(Cont)
3. Software (cont.) - Application software
 Run on top of operating system
 Execute tasks that users wish to perform
• Web surfing, Social Network Service, Audio,
Video playback
12

Input
Variables
Output
(User Interface)
Variables
(Link to other Systems)
Embedded Computer
Software
Hardware
Signal
Conditioning
Data
Conversion
Output
Drive
(display, keypad etc.)
The Embedded System – Generic
Block Diagram
13

Real-Time Systems
• Real-time operating system (RTOS): Multitasking
operating system for real-time applications
 RTOS is valued for how quickly and/or predictably
respond to a particular event
• Hard real-time systems are required to complete a
critical task within a guaranteed amount of time
• Soft real-time systems are less restrictive
 Implementing real-time system requires a careful
design of scheduler
• System must have the priority-based scheduling
 Real-time processes must have the highest
priority
14

Operating Systems for Embedded
Systems
• RTOSs
 VxWorks
 VRTX (Versatile Real-Time Executive)
 uC/OS-II
• Palm OS
• Palm OS: Embedded operating system initially developed by U.S. Robotics-
owned Palm Computing, Inc. for personal digital assistants (PDAs) in 1996
• Android
 Based on modified version of Linux 2.6 kernel
 Currently supporting ARM, MIPS, and x86
15

General-Purpose (GP) Computer
Systems
16

CPU
North
Bridge
South
Bridge
Main
Memory
(DDR2)
FSB
(Front-Side Bus)
DMI
(Direct Media I/F)
Hard disk
USB
PCIe card
Peripheral
devices
Graphics
card
A Computer System (till 2008)
17

Keep in mind that CPU and computer
systems are evolving at a fast pace!
CPU
North
Bridge
South
Bridge
Main
Memory
(DDR2)
FSB
(Front-Side Bus)
DMI
(Direct Media I/F)
Core 2 Duo – based Systems
• Core i7 (Ivy Bridge) – based Systems
 FDI: Flexible Display Interface
 SPI: Serial Peripheral Interface
 SMBus: System Management Bus
Past, Present and More…
18

CPU
North
Bridge
South
Bridge
Main
Memory
(DDR2)
FSB
(Front-Side Bus)
DMI
(Direct Media I/F)
CPU
North
Bridge
South
Bridge
Main
Memory
(DDR3)
Quickpath (Intel) or
Hypertransport (AMD)
DMI
(Direct Media I/F)
Core 2 Duo – based Systems • Core i7– based Systems
Keep in mind that CPU and computer systems are evolving at a fast pace
Present, Near Future and More…
19

32-bit (i586) 64-bit (x86_64)
32-bit (i686)
2009
1st Gen. Core i7
(Nehalem)
2012
3rd Gen. Core i7
(Ivy Bridge)
2013
4th Gen. Core i7
(Haswell)
2nd Gen. Core i7
(Sandy Bridge)
2011
4-bit 8-bit 16-bit 32-bit (i386)
x86 History (Cont.)
20

• What is x86?
 Generic term referring to processors from Intel, AMD and
VIA
 Derived from the model numbers of the first few generations
of processors:
• 8086, 80286, 80386, 80486  x86
 Now it generally refers to processors from Intel, AMD, and
VIA
• x86-16: 16-bit processor
• x86-32 (aka IA32): 32-bit processor * IA: Intel
Architecture
• x86-64: 64-bit processor
• Intel takes about 80% of the PC market and AMD takes about
20%
 Apple also have been introducing Intel-based Mac from Nov.
2006
x86?
21

• We call North and South Bridges as Chipset
• Chipset has many PCIe devices inside
• North Bridge
 Memory controller
 PCI express ports to connect Graphics card
• South Bridge
 HDD (Hard-disk) controller
 USB controller
 Various peripherals connected
• Keyboard, mouse, timer etc
 PCI express ports
Chipset
22

• Backplane (backbone) bus
 Industry standard
• e.g., PCIexpress
 Allow processor, memory and I/O
devices to coexist on a single bus
 Used as an intermediary bus connecting
I/O busses to the processor-memory
bus
• I/O bus
 Industry standard
• e.g., SATA, USB, Firewire
 Usually is lengthy and slower
 Needs to accommodate a wide range of
I/O devices
CPU
North Bridge
South
Bridge
Main
Memory
(DDR2)
FSB
(Front-Side Bus)
DMI
(Direct Media I/F)
Hard disk
USB
Graphics
card
Backplane bus
I/O bus
Types of Buses
23

PCI, PCI Express Devices
• PCI (Peripheral Component Interconnect)
 Computer bus connecting all the peripheral
devices to the computer motherboard
• PCIe (PCI Express)
 Replaced PCI in 2004
 Point-to-point connection
 PCIe 2.0
 Introduced in 2007
 PCIe 3.0
 Introduced in 2010
PCI slot
PCI express slots
PCI express slot x16
24

An Old GP Computer System
Example
25

PCI Express Slots in GP Systems
PCI express
slot
26

Software Stack
Computer Hardware
(CPU, Chipset, PCIe cards ...)
BIOS
(AMI, Phoenix Technologies …)
Operating System
(Linux, Vista, Mac OS …)
Applications
(MS-office, Google Earth…)
API
(Application Program I/F)
BIOS provides
common I/Fs
27

How the GP Computer System
Works?
• x86-based system starts to execute from the reset address
0xFFFF_FFF0
 The first instruction is “jmp xxx” off from BIOS ROM
• BIOS (Basic Input/Output System)
 Detect and initialize all the devices (including PCI devices via
PCI enumeration) on the system
 Provide common interfaces to OS
 Hand over the control to OS
• OS
 Manage the system resources such as main memory
• Control and coordinate the use of the hardware among
various application programs for the various users
 Provide APIs for system and application programming
28

So… What?
• How is it different from embedded systems?
 General-purpose computer systems provide
programmability to end-users
• You can do any kinds of programming on your PC
 C, C++, C#, Java etc
 General-purpose systems should provide backward
compatibility
• A new system should be able to run legacy software,
which could be in the form of binaries with no source
codes written 30 years ago
 So, general purpose computer system becomes
messy and complicated, still containing all legacy
hardware functionalities
29

All Arduino boards contain a microcontroller, which is a small computer. It then describes some popular Arduino boards like the Uno, Nano, Due, and Mega and their key specs and applications.

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