Real Time Embedded Systems Introduction
Dr. AlexBystrov Dr.
School of Engineering University of Newcastle upon Tyne
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1. Hardware/software design and modelling of embedded computing systems
2. Protocols, design concepts and scheduling
3. Experience in programming of real-time systems
The formal lectures cover a set of hardware and software aspects
◮ Real-time aspect: Petri net model, concurrency, arbitration, communication modelling, ACM
◮ Embedded design: threads, processes, scheduling, programming, setting up communication links between processes.
◮ ACM and architectures with Dr. develop skills and help to understand deeper the theory.
◮ Software design – scheduler, real-time, ARM platform
The formal lectures cover a set of hardware and software aspects
◮ Real-time aspect: Petri net model, concurrency, arbitration, communication modelling, ACM
◮ Embedded design: threads, processes, scheduling, programming, setting up communication links between processes.
◮ ACM and architectures with Dr. develop skills and help to understand deeper the theory.
◮ Software design – scheduler, real-time, ARM platform
Assessment
◮ no exams this year
◮ 40% presentation
◮ 60% written report 3000 words
Deadline: the last Friday of the semester
What is an embedded system?
Definition: “nearly any computing unit not used as a desktop computer” (Vahid & Givargis 2002)
◮ What about laptops, servers and mainframes?
◮ What if the desktop is used to control something, to route the
network or just for Skype?
A better definition (Gupta 2002):
◮ employs a combination of hardware+software to perform a specific function;
◮ is a part of a larger system that may not be a “computer”;
◮ works in a reactive and time-constrained environment.
General characteristics (Williams 2006)
◮ Latency limit
◮ Event-driven scheduling
◮ Time-driven scheduling
◮ Low-level programming
◮ SW tightly coupled to special HW
◮ Dedicated specialised functions
◮ Computer inside a control loop
◮ Multi-tasking
◮ Continuous running
◮ Various specific metrics: safety-critical app., security, power constraints, variability-tolerant design, etc.
Software/hardware co-design
◮ Software provides features and flexibility;
◮ Hardware (processors, ASICs, memory, accelerators, etc.) is
used for performance, fault-tolerance and security.
Example of DSP:
◮ DSP code
◮ processor cores
◮ application-specific gates ◮ analogue I/O
[Gupta 2002]
Software/hardware co-design
◮ Software provides features and flexibility;
◮ Hardware (processors, ASICs, memory, accelerators, etc.) is
used for performance, fault-tolerance and security. Example of DSP:
◮ DSP code
◮ processor cores
◮ application-specific gates ◮ analogue I/O
[Gupta 2002]
Common design metrics
Unit cost:
Total cost:
fabrication cost of a single copy of the system, excluding NRE cost
(Non-Recurring Engineering cost) one-time monetary cost of designing the system
NRE_cost + Unit_cost * Number_of_units
Per product cost: NRE_cost/Number_of_units + Unit_cost
Time-to-prototype: time to develop a working version
Time-to-market: time to develop a system to the point when it can
be released and sold to customers
Flexibility: the ability to change the functionality of the system without incurring heavy NRE costs
Physical metrics
Time-to-market metric (simplified model)
NRE and Unit Cost design metrics
Design productivity gap (HW)
Moore’s law…
The gap is bigger than it seems…
◮ “The Mythical Man-Month” by 1975
◮ Scaling up the group “hits the wall” at some point
◮ After that point adding new men does NOT increase overall productivity
◮ Individual productivity goes down
Conclusions
◮ Embedded systems, including real-time, are everywhere and represent all electronic applications
◮ Everything above is an Introduction – the really important and complex stuff will follow
◮ Attendance is important
◮ Finding the literature sources is extremely important
◮ This is an advanced course – please help us to analyse your needs as a learner, so we could support you to a maximum extent
◮ Technical content of the introduction covered a definition of an embedded systems and metrics
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