Transcript Issues in System-level HW-SW Co

Define Embedded Systems
Small (?) Application Specific
Computer Systems
Typical Characteristics
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Real time
Small sized
Low power
Cost effective
Heterogeneous HW/SW
Implementations of
Embedded Systems
Only HW,
High cost and
High performance.
Cost
Mixed HW-SW,
Medium cost and
performance.
Only SW,
Low cost and
Low performance.
Performance
Additionally, flexibility and tight time to market
requirements favour SW implementations.
System-on-Chip Design
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Current day embedded systems utilize customized
embedded processors
Embedded processors have System-on-Chip (SoC)
architectures
SoC incorporate several different discrete cores on
the same die.
SoC design methodology strongly mirror boardlevel design.
Hence, system-level hardware-software co-design
has also been utilized for SoC design.
This course will utilize platform FPGAs as a vehicle
for SoC design.
Control Intensive versus
Computation intensive
• Control intensive application offer less opportunities
for parallelism as opposed to computation intensive
applications.
Examples ???
• Hence, control intensive applications are more
amenable for micro-controller implementation.
• Computation intensive applications are more
amenable to custom-hardware (ASIC) or
FPGA implementation.
Define Hardware-Software
Codesign
It is the concurrent and co-operative design
of hardware and software components of
an embedded system.
HW Design Abstraction
Processor-Memory Level
RT Level
Logic Gates
Transistors
Polygons of Silicon
Levels of
Design
Abstraction
Digital System Design
Translation or
Design
Specification
Verification by
Simulation
Traditional System-level Design Flow
Informal Specification,
Constraints
System model
Architecture design
HW/SW implementation
Fail
Test
Success
Implementation
Prototype
Traditional System-level Design Flow
Lack of system-level performance evaluation
 HW/SW specification implemented before
performance/energy/cost verification
 Long system-level design times
 Expensive under performance/energy/cost
failures
 Over-design is common
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System-level HW-SW Co-Design
Informal Specification,
Constraints
System model
Performance
evaluation
HW/SW implementation
Fail
Test
Success
Implementation
Prototype
Component
profiling
Architecture design
System-level HW-SW
Co-design
IDEA
Specification
Components
(HW,SW)
Constraints
System-level
HW-SW Co-design
HW behavior
and components
Memory hierarchy
and mapping
Interconnect
and buses
SW behavior, RTOS,
schedule policy
and processors
Issues in System-level
HW-SW Co-design
• Specification of functionality and constraints.
Simulation of functionality.
• Components as building blocks
• SW processors: DSP and Micro-controllers
• HW co-processors: ASICs, FPGA
• Storage elements: Cache, Scratchpad, SRAM, DRAM
• Interconnection elements: Buses and arbiters
• Interface and I/O units: DMA, UART, D/A, A/D,
Wireless communication
• Software platform: RTOS and scheduling
Issues in System-level
HW-SW Co-design
• Performance analysis (timing, power, area)
• Design and optimization (timing, power, area)
• Architecture selection: processing elements,
memory units and inter-connect.
• RTOS and schedule scheme.
Attributes of Embedded computing
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Real-time Operation.
Sensing & Control.
Low cost.
Low power consumption.
Dependable.
Autonomous.
Where Embedded Systems are Used..? [1]
Current Accomplishments
 Current Products:
 Automotive Control:
• Improved fuel efficiency.
 Avionics:
• Navigation, Collision avoidance.
 Medical Monitoring Systems.
 Smart Homes.(washing machines, Clocks etc.).
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Future Uses:
 Intelligent Highways.
 Chemical and Biological Sensors etc.
An Embedded Control
System Designer’s View
A Customer View
Specification
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A more precise description of the system:
– should not imply a particular architecture;
– provides input to the architecture design process.
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May include functional and non-functional
elements.
May be executable or may be in mathematical form
for proofs.
GPS specification
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Should include:
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What is received from GPS;
map data;
user interface;
operations required to satisfy user requests;
background operations needed to keep the system
running.
Architecture design
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What major components go satisfying the
specification?
Hardware components:
– CPUs, peripherals, etc.
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Software components:
– major programs and their operations.
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Must take into account functional and nonfunctional specifications.
GPS moving map block
diagram
GPS
receiver
search
engine
database
renderer
user
interface
display
GPS moving map
hardware architecture
display
frame
buffer
CPU
GPS
receiver
memory
panel I/O
Processor Selection
Processor selection
Scope of Codesign
Steps
Steps Refined
Map between behaviour and
architecture