1. Introduction to Embedded Systems

2. Outline What is an embedded system
Characteristics and Classification of Embedded Systems
Systems-on-a-Chip
Distributed Systems
Internet-of-Things
Embedded Systems Design Challenges
Real-Time Embedded Systems

3. Microprocessors for Embedded systems
Computing systems are everywhere
Most of us think of “desktop” computers
PC’s
Laptops
Mainframes
Servers
But there’s another type of computing system
Far more common...

4. Embedded systems overview
Embedded computing systems
Computing systems embedded within electronic devices
Hard to define. Nearly any computing system other than a desktop computer
Billions of units produced yearly, versus millions of desktop units
Perhaps 50 per household and per automobile
A lot more programming is done for embedded systems than desktop computers or servers
Computers are in here...
and here...
and even here...
Lots more of these, though they cost a lot less each.

5. A “short list” of embedded systems
Anti-lock brakes
Auto-focus cameras
Automatic teller machines
Automatic toll systems
Automatic transmission
Avionic systems
Battery chargers
Camcorders
Cell phones
Cell-phone base stations
Cordless phones
Cruise control
Curbside check-in systems
Digital cameras
Disk drives
Electronic card readers
Electronic instruments
Electronic toys/games
Factory control
Fax machines
Fingerprint identifiers
Home security systems
Life-support systems
Medical testing systems
Modems
MPEG decoders
Network cards
Network switches/routers
On-board navigation
Pagers
Photocopiers
Point-of-sale systems
Portable video games
Printers
Satellite phones
Scanners
Smart ovens/dishwashers
Speech recognizers
Stereo systems
Teleconferencing systems
Televisions
Temperature controllers
Theft tracking systems
TV set-top boxes
VCR’s, DVD players
Video game consoles
Video phones
Washers and dryers
And the list goes on and on

6. Definitions Broad definition: Narrow definition:
Any computer system that is not a general-purpose computer
That would include robots, and all portable devices
Narrow definition:
A computer system (software and hardware) that interacts with its physical environment, mainly without human intervention
That would exclude printers, modems, portable devices such as dvd and mp3 players, etc.

7. Some common characteristics of embedded systems
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

8. Considerations in embedded system design
An embedded system receives input from its environment through sensors, processes this input and acts upon its environment through actuators
Besides the usual software and hardware design issues the embedded system designer must consider the properties of the sensors and actuators and the environment itself
The ultimate test of an embedded systems are the laws of physics

9. Classification of Embedded Systems
Centralized vs distributed
Real-time vs non real-time
Hard deadline
Failsafe
Fail-operational
Soft deadline
Firm deadline
Battery powered vs mains powered
System-on-Chip vs discrete element

10. What is real-time? Is there any other kind?
A real-time computer system is a computer system where the correctness of the system behavior depends not only on the logical results of the computations, but also on the physical time when these results are produced.
By system behavior we mean the sequence of outputs in time of a system.

11. Real-time means reactive
A real-time computer system must react to stimuli from its environment
The instant when a result must be produced is called a deadline.
If a result has utility even after the deadline has passed, the deadline is classified as soft, otherwise it is firm.
If severe consequences could result if a firm deadline is missed, the deadline is called hard.
Example: Consider a traffic signal at a road before a railway crossing. If the traffic signal does not change to red before the train arrives, an accident could result.

12. Fail-Safe hard-deadline RT systems
If a safe state can be identified and quickly reached upon the occurrence of a failure, then we call the system fail-safe.
Failsafeness is a characteristic of the controlled object, not the computer system.
In case a failure is detected in a railway signaling system, it is possible to set all signals to red and thus stop all the trains in order to bring the system to a safe state.
In failsafe applications the computer system must have a high error-detection coverage.
Often a watchdog, is required to monitor the operation of the computer system and put it in safe state.

13. Fail-Operational hard-deadline RT systems
In fail-operational applications, threre is no safe state
a flight control system aboard an airplane.
The computer system must remain operational and provide a minimal level of service even in the case of a failure to avoid a catastrophe

14. Typical Embedded System Components
Sensors: Allow the system to “read” the environment
Processing Elements: Control of the embedded system
Actuators: Allow the system to act on its environment
Network Connection: Local or internet, allowing exchange of information

15. An embedded system example – 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

16. A System-on-a-Chip: Example
Courtesy: Philips

17. Design at a crossroad System-on-a-Chip
RAM
500 k Gates FPGA
+ 1 Gbit DRAM
Preprocessing
Multi-
Spectral
Imager mC
system
+2 Gbit
DRAM
Recog-
nition
Analog
64 SIMD Processor
Array + SRAM
Image Conditioning
100 GOPS
Embedded applications where cost, performance, and energy are the real issues!
DSP and control intensive
Mixed-mode
Combines programmable and application-specific modules
Software plays crucial role

18. The Future of Embedded Systems
In the past an embedded system was more or less isolated
In the past decade Wireless Sensor Networks have changed that
Today embedded systems + internet connection = Internet of Things !
Near future: Embedded systems + internet + mobile devices + cloud computing + artificial intelligence + ? = smart environment

19. IoT forecasts
Global Internet of Things (IoT) market reached USD Billion in 2015
is expected to reach USD Billion by 2023
the market is projected to register a CAGR of 13.2%
The number of connected IoT (Internet of Things) devices, sensors and actuators will reach over 46 billion in 2021

20. IoT Embedded system with internet connection
Not quite as simple as it sounds
Increased need for security
Safety issues
Direct machine to machine (M2M) communication