嵌入式系统1-介绍

Need careful co-design of h/w & s/w!
Source: Mani Srivastava®
• Time matters
Embedded Systems Fundamentally Different from General Purpose Systems
– “As fast as possible” is not good enough
– Predictable, repeatable timing – Support for common operations (e.g. FIR filters) – Need for specialized data types (fixed point, bit vectors)
• Programs need to run (essentially) forever
Source: Edward Lee®
More Characteristics of Embedded Systems
• Part of a larger system – not a “computer with keyboard, display, etc.” • HW & SW do application-specific function – not general purpose – Much of the application is known a priori – but definition and development concurrent • Some degree of re-programmability is essential – flexibility in upgrading, bug fixing, product differentiation, product customization • Interact (sense, manipulate, communicate) with the external world • Never terminate (ideally) – fundamentally different from TM • Operation is time constrained: latency, throughput • Other constraints: power, size, weight, heat, reliability etc. • Increasingly high-performance (DSP) & networked
Office Equipment
What is an Embedded Computing System?
• "A miniature computation system developed for low power, high performance devices" • "A system where different things are brought together to perform a particular application" • "...defined as any system which does a fixed number of predefined set of tasks with the deadlines" • "A system that is specialized" • "A system that contains a micro computer controller" • "An electronic device with computing capability, but whose main purpose isn't computing (i.e. cellphone, appliance, ..., not a laptop)"
• e.g. Java ring, smart cards, printers
– cameras, disks etc. that sit directly on networks
• Increasing need for flexibility
– time-to-market under ever changing standards!
– to eliminate host, and remotely monitor/debug – embedded Web servers
• e.g. IQEye camera • e.g. Mercedes car with web server
– embedded Java virtual machines
Embedded Systems
Credits
• For this class, some slides will be adopted from other researchers. Reordering and modifications may have been made. All credits go to the original authors, and all errors are mine.
Source: Mani Srivastava®
Advanced Car Controls
Source: Alberto Sangiovanni-Vincentelli®
HVAC Building Monitoring
Source: Alberto Sangiovanni-Vincentelli®
What is an Embedded Computing System?
• "Latest computing, signal processing, networking, components packaged into a small form factor. Unique resource and power constraints." • "A digital system interfacing with hardware." • "A system on the border between the physical and digital worlds."
What is an Embedded Computing System?
• "Everything I use now is practically an embedded system" • "A system that users cannot install their own application software on" • "Miniaturized system that's a combination of HW/SW/ Firmware for a specific application or cause." • "A system designed for a specific task, not a multipurpose computer, which often has restraints such as memory, power, size, cost. Usually all components needed are local (memory, i/o, processor, application specific ICs)
Biotechnology
Hearing Aids Pacemakers Systems Biology
Source: Alberto Sangiovanni-Vincentelli®
More Examples…
Avionics
Household Appliances
Home Entertainment
Source: Mani Srivastava®
Key Recent Trends
• Increasing computation demands
– e.g. multimedia processing in set-top boxes, HDTV
• Increasingly networked
– Memory usage has to be bounded (no leaks!!) – Rebooting is not acceptable
What about Real-Time?
Байду номын сангаас
Making it as fast as possible not good enough

What if you need “absolutely positively on time”? Today, most embedded software engineers write code, build your system, and test for timing. True embedded system design must specify dynamic behavior (including timing) and “compile” implementations that meet the behavior.
What is an Embedded Computing System?
• "A system designed to achieve certain application. Get some particular input and perform some particular active (sic)" • "Computer with relatively small size, eliminating unnecessary functionality, cheaper and easier to use for even monkey if needed" • "Combination of h/w and w/w designed for a specific set of purposes (as opposed to a PC which can be programmed to close to anything). The system usually operates under resource constraints