Embedded Systems

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jan@imm.dtu.dk

Jan Madsen

Informatics and Mathematical Modeling Technical University of Denmark Richard Petersens Plads, Building 321

DK2800 Lyngby, Denmark

Embedded Systems

introduction

Wireless Sensor Networks

Dataopsamling

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02131 Embedded Systems Jan Madsen [3]

Sensor Node Architecture

rtos

Mem

cpu

^radio

sensor

sensing

processing communicating battery

Sensor Node Architecture

rtos

1Kbps - 1Mbps, 3-100 Meter,

Lossy Transmissions

8-bit, 10 MHz

Slow

computation

(3)

02131 Embedded Systems

rtos

Mem

cpu

^radio

sensor

battery C programming

practice, test, verification Assembly language basics Operating systems usage

Processor design

Microprocessor basics Specialized hardware Interfaces

SW-SW, HW-HW, SW-HW

? ”Det er ok at vise din kærste din nye

computer, hvis du selv har lavet den”

(4)

Computing systems

?Desktop, workstations, mainframes and servers

?Millions of such systems built every year!

?But, billions of computing systems are built every year for a very

different purpose ...

?Embedded systems accounts for 99% of all computing systems!!!

Embedded systems

if ...

then ... else ...

for { ...

..}

func

001010100101101 101011101101010 001010011101101 110101001010011 101010101010001 111101010111101 010111101101010

bit-pattern

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Embedded systems

? Systems which use a computer to perform a specific function, but are neither used nor perceived as a computer

? They are embedded within larger electronic devices

? Repeatedly carrying out a particular function

? Often completely unrecognized by the device’s user

? Heavily resource constrained

Embedded Computing Systems?

? Fabrication equipment

? Automotives

? fuel injection, anti-lock brakes, airbags, etc.

? Avionics

? Flight control systems, anti-collision systems, etc.

? Telecommunication

? Mobile phones

? Authentication systems

? SMARTpen

? Consumer electronics

? Game consoles, TV sets, video, DVD, mp3, etc.

? Microwave ovens, washing machines, etc.

? Medical systems

? Hearing aid, smart pills, etc.

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Medical systems: Hearing aid

Medical systems: Diagnostics

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Smart pills – 1st generation

Smart pills – 2nd generation

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Embedded Computing Systems?

?Smart buildings

?Energy control, air-conditioning, safety systems, etc.

?Sensor networks

?Environmental monitoring, animal monitoring, etc.

?Wearable computing

Wearable computing

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Wearable computing

Embedded Computing Systems?

?Smart buildings

?Energy control, air-conditioning, safety systems, etc.

?Sensor networks

?Environmental monitoring, animal monitoring, etc.

?Wearable computing

?Robotics

?Humanoid, micro-insects, etc.

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Flying micro-insects

How do we design these

embedded systems?

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Embedded systems design

hardware software

validation validation

hardware prototype

software prototype

Several design groups

Separated validations

Prototype realization

hardware model

software model

Problems arise at a very late point in the design process

Embedded systems design

Size and speed requirements

void UnitControl() {

up = down = 0; open = 1;

while (1) { while (req == floor);

open = 0;

if (req > floor) { up = 1;}

else {down = 1;}

while (req != floor);

open = 1;

delay(10);

} } }

C/C++/Java

001010100101101 101011101101010 001010011101101 110101001010011 101010101010001 111101010111101 010111101101010

bit-pattern DSP chip

Need to know about hardware!

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Hardware (chip) design

Size and speed requirements

ASIC netlist Layout

open = 0;

else {down = 1;}

open = 1;

delay(10);

} } }

C/C++/Java

architecture

+ energy

Principples of Codesign

while (1) {

open = 0;

SW

synthesis

CPU

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Principples of Codesign

open = 0;

else {down = 1;}

open = 1;

delay(10);

} } }

open = 0;

else {down = 1;}

open = 1;

delay(10);

} } }

SW synthesis

HW synthesis Interface

synthesis

System-on-Chip

BREAK

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Processor technology

?Architecture of computation engine

?Does not have to be programmable

?Differs in its specialization towards a particular application

?Manifests different design metrics

Processor: General-purpose

?Designed to:

?maximize the number of devices sold

?suitable for a variety of applications

?Architecture contains:

?program memory

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Processor: General-purpose

?Used by the embedded system designer to

program the processor’s memory to carry out the required functionality

?This portion of an implementation is often referred to as the “software” portion

Software

? Elements of computation

? Transform data

? Store data

? Move data

if ...

then ... else ...

for { ...

..}

func

cpu

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Processor

? Architecture components

? Processing elements – transform data

? Memories – store data

? Interconnect – move data

if ...

then ... else ...

for { ...

..}

func

Processor: General-purpose

if ...

then ... else ...

for { ...

func

inst mem controller datapath data mem

func ir cu

*

reg

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Processor: General-purpose - example

if ...

then ... else ...

for { ...

..}

func

pc

ir cu

reg +/-

**x = x + A[i] * p1**

* ^A[i]

p1

5 cycles

Processor: Single-purpose

?Digital circuit designed to execute exactly one program

?This portion of an implementation is often referred to as the “hardware” portion

?Other common terms:

?Co-processor

?Accelerator

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Processor: Single-purpose (ASIC)

? High performance

? Low power

? Complex design flow

? No flexibility

if ...

then ... else ...

for { ...

..}

func

controller datapath cu

+/-

*

⁺

mem

Processor: Single-purpose – example

if ...

then ... else ...

for { ...

func

controller datapath cu

*

⁺

mem

A[i]

p1

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Processor: Application-specific

?Designed for a particular class of applications with common characteristics

?Serve as a compromise between the two other processor types

?Examples are digital signal processors (DSPs)

Processor: Application-specific

?May require large NRE cost to build the processor itself and to build a compiler

?Automatically generating such processors and associated retargetable compilers are currently very hot research topics

?Lack of good compilers requires many embedded system designers to program in assembly

language

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Processor: Application-specific (ASIP)

? Costumized datapath – 16, 8 or 4 bit

? Optimized for particular class of programs - MACC

? ”Simple” design flow

? High flexibility

if ...

then ... else ...

for { ...

..}

func

pc

ir cu

reg +/-

*

+

Processor: Application-specific - example

if ...

then ... else ...

for { ...

func

func ir cu

+ reg

* p1

A[i]

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Summary

?Processors

?General-purpose

?Single-purpose (ASIC)

?Application-specific (ASIP)

?Common model

?FSMD - Finite State Machine with Datapath

controller datapath

What you will do!

if ...

then ... else ...

for { ...

..}

func