Introduction to Embedded Architecture

Embedded Systems
Chapter 1:Embedded Architecture
BY
AMRUTA CHINTAWAR
Friday, September 04, 2015 By AMRUTA CHINTAWAR 1

Embedded Architecture
• Embedded computers
• Characteristics
• Applications
• Challenges
• Embedded memories
• ES design process
• Requirement specifications
• Architecture
• H/W and S/W components
• System Integration
• Design examples

Definition
• Embedded computing system: any
device that includes a programmable
computer but is not itself a general-
purpose computer.
• System has a S/W embedded into
Computer H/W, which makes the
system dedicated for an application
or specific part of an application or
product or part of a larger system.

Definition
• Embedded systems (ES) = information
processing systems embedded into a
larger product
• Main reason for buying is not information
processing

Comparison

Various Embedded Mobile Systems
Desktop PC
Data Processing Consumer
Communication Automotive & etc.
DTV
Media
Center
Game
Console
DSC
DVC
Car Navigation
DVD
Telematics
MP3 Player
Credit Card
Cellular Phone
Notebook PC
Internet
Smart Phone PDA
Bluetooth
Audio
Friday, September 04, 2015 6By AMRUTA CHINTAWAR

Examples
• Biomedical Instrumentation: ECG Recorder, Blood cell
recorder, patient monitor system
• Communication system: pagers, cellular phones, cable TV
terminals, fax and transreceiver, video games and so on.
• Peripheral controllers of a computer –keyboard controller,
DRAM controller, Printer Controller, LAN controller, Disk
drive Controller

Examples
• Industrial Instrumentation- Process controller,
DC motor controller, robotic system, CNC
machines controller, close loop engine
controller, industrial moisture recorder cum
controller
• Scientific –digital storage system, CRT display
controller, spectrum analyzer.

Example

Example: Digital Thermostat

Example: Mobile phone

Characteristics
• Dedicated and sophisticated functionality
• Low manufacturing cost, low power
• Complex Algorithm
• GUI, other user interface
• Reliability
• Real Time operations
-latencies
-Deadlines
• Multirate Operations
-Audio
-Vedio

Design Metrics/Goals
• Reliability
• Power Consumption
• Cost :NRE cost & Manufacturing cost
• Weight/size
• Time: time to prototype & time to market
• Flexibility
• Performance
• Debuggability
• Safty & maintaince
• Maximum usage of resources

Challenges
• How much hardware do we need?
– How big is the CPU? Memory?
• How do we meet our deadlines?
– Faster hardware or cleverer software?
• How do we minimize power?
– Turn off unnecessary logic? Reduce memory accesses?
• Does it really work?
– Is the specification correct?
– Does the implementation meet the spec?
– Reliability in safety-critical systems

Challenges
• How do we work on the system?
– Complex testing
• How do we test for real-time characteristics?
• How do we test on real data?
– Limited observability and controllability
– Restricted development environments
• What is our development platform?

Level Abstraction
requirements
specification
architecture
component
design
system
integration

Architecture

Components of Embedded system
 H/W
- Processor
- Power source and clock
- Reset circuit
- Memory Unit
- Interrupt Handler
- Linking Embedded System H/W
- I/O communication Unit
 S/W
- ROM image/Applications/w
- Programming Languages
- Device Drivers
- Program Models

Components of Embedded system
 RTOS/EOS
 S/W Tools
- Development tools
- Simulator
- Project Manager
- IDE

Types of Cores
Requirments
-Able to solve complex Algorithm
- Meet Deadlines
- No.of Bits to be operated
- Bus Width
- Clock Frequency
- Performance(MIPS/MFLOPS)

Types of Cores
 GPP: General Purpose Processor
-Microprocessors
-Embedded Processors
 ASIP: Application Specific Instruction Processor
-Micro controller
-Embedded Micro controller
-DSP and media Processor
-Network Processor
 SPP: Single Purpose Processor
-Coprocessors eg:Math-coprocessor
-Accelerators eg:java acce
-Controllers eg:DMA

Types of Cores
 ASIC/VLSI chip: Application specific
Integrated circuit
-GPP/ASIP integrated with analog
circuits on VLSI chip using EDA tools.
 ASSP:Application Specific System
Processor
-set top box
-Mpeg
-HD tv
eg:vedio Processors
 Multicore Processors/Multiprocessor
using GPP
eg:Embedded firewall cum
Router

Power Sources,Clock and Reset Circuit
 Power supply
-Own supply
-Supply from System
-Charge Pumps
 Clock
-External Clock supply
-Oscillator
-RTC
 Reset
-Power On
-External/Internal Reset
-WDT
-BOR

Memory Unit,Interrupt Handlers
Memory
 ROM/EPROM/FLASH (internal/External)
 RAM
 Caches
Interrupt Handler
 External port interrupt
 I/O,Timer, RTC, interrupts
 S/W Interrupt/Exceptions
Linking ES H/W
 Multiplexers
 Decodes

I/O communication Unit
 I/O,O/P devices
-Sensors,
-actuators
-converters
-keypads
-displays
 Buses
-Parallel Buses
-serial buses

S/W-ROM Image, Programming
Language
 ROM Image
-Final Machine s/w
-Can be compressed code or data
-Distinct ROM image in distinct ES
 Programming Languages
-Machine
-Assembly
-High Level

S/W-Device Driver, Managers
It connects external H/w with Processor
 Controlling
 Receiving
 Sending
Part of OS
 Manages device
 Initializing
 Testing
 Detecting
 Allocating port addresses

RTOS/OS
It performs functions
 Multitasking
 Scheduling
 Management
 Resource protection
 Interprocess Communication
eg: Ucos-II, Vxworks, windows CE, RT
linux,QNX

Embedded Memories
Internal RAM at µc –SRAM used as reg, temp data,
stack
RAM AT SoC or External RAM
Internal/external caches at µp -hold copy of
system memory pages
External RAM chips -DRAM used to hold extra data
Flash EPROM/EEPROM -result stored in NV memory
ROM/PROM/MROM/OTP -Application S/W, OS
Memory addresses at system ports -RAM buffers
Memory Stick -large storage such as audio, video

I/O Devices
• DAC using PWM
• ADC
• LCD,LED and Touch Screen
• Keypad/keyboard/T9 keypad
• Pulse dialer
• Modem
• Transceiver
• Interrupt handler -mechanism to handle various
interrupts and also to deal with pending
services

Difference between RISC and CISC
RISC CISC
Reduced instruction set Complex Instruction set
Maximum instructions are
single cycle(fixed size),thus
supports pipelining
Variable size Instructions,so
generally do not have
pipelining
Orthogonal instruction set Non-Orthogonal
Operations are performed on
registers, so large no of
Registers.
For memory only Load and
Store
Operations are performed on
both registers and memory.
Limited number of GPRs

Difference between RISC and CISC
RISC CISC
Hardwired Control unit Microcode control Unit
Small in size with resp to die area
and No.of pins
Comparatively large in size since
more complex instruction needs
to be implemented.
Harvard architecture Harvard or Von-Neuman
Eg:PIC18,ARM 8051,8086

SoC
• System designed on a single chip
• Processor with all analog, digital and S/W
build on a single VLSI chip

SoC

SoC
It embeds
• EGPP or ASIP
• SPP or Multiprocessor
• N/W bus protocol
• Encryption and Dycryption
• Signal processing such as FFT,DCT
• Memories
• IP-Intellectual
• PLDs or FPGA
• Accelerators or other logic and analog units

IP-Intellectual Property
• A standard source solution for synthesizing a
higher level component by configuring an
FPGA core/VLSI core
• Components-gate level sophistication in
circuits above that of counter, register,
multiplier, FLU and ALU

H/W and S/W Co-Design

H/W and S/W Co-Design
• Joint optimization of H/W and S/W to
optimize design metrics
• S/W and H/W partitioning at early stage
• Both proceed in parallel with interactions and
feedback
• System specification required
• H/W synthesis
• S/W synthesis
• Simulation
• Implementation

Development Process

Levels of Abstraction from Top to Bottom
• Requirements
• Specifications
• Architecture
• Components
• System Integration

Requirement
Complete clarity of:
• Required Purpose
• Inputs
• Outputs
• Functioning
• Design metrics
• Validation requirements for finally developed
system specifications
• Consistency in the requirements

Specifications
• Clear specification of customer expectations
from the product
• Needs specification for
– H/W, eg: Peripherals, Divices,Processors and
memory specifications
– Data types and processing specifications
• Expected system behavior specifications
• Constraints of design
• Expected lifecycle specifications of the
product

Specifications
• Process specifications analyzed by making list
of I/Ps on event list, O/Ps on events, process
activated on each event

S/W Architectural Layers
• How the different elements- data structures,
data bases, algorithms, control functions,
state transition functions, process, data and
program flow are to be organized
• Data base and Data structure design-
appropriate for given problem
Eg: tree like structure

H/W Components
• Processors, ASIP, Single Processors
• All Types of Memory as per requirement
• Internal and External peripherals and
devices
• Ports and Buses in the system
• Power sources and battery

Design Examples
• ACVM
• Smart Card
• Digital Camera
• Mobile phones
• Mobile Computer
• Set of Robots

ACVM

ACVM Block diagram
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ACVM
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ACVM
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ACVM H/W
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ACVM H/W
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ACVM S/W
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SMART CARD

SMART CARD
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SMART CARD
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ROM
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ROM
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Embedded S/W
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Smart Card OS Special Features
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Smart Card OS Limitimg Features
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Smart Card OS file System
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DIGITAL CAMERA

Digital Camera H/W Components
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Digital Camera
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Digital Camera Arrangements
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Internal Units
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Internal Units
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ASIP and Single purpose processors
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Digital Camera H/W
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Digital Camera S/W
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Introduction to Embedded Architecture

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