What is an embedded system? Embedded systems (ES) = information processing systems embedded into a larger product
An embedded system is a computerdesigned for specific controlfunctions within alarger System.It is embedded as a part of a completeoften including hardware andmechnical part.Embedded system contain processingcores that are typically either Micro-controllers or digital signal processors.
Embedded Systems Model What the Embedded Systems Model indicates is that all embedded systems share one simi-larity at the highest level; that is, they all have at least one layer (hardware) or all layers (hardware, system software and application software) into which all components fall. The hardware layer contains all the major physical components located on an embedded board, whereas the system and application software layers contain all of the software located on and being processed by the embedded system.
Embedded Systems Design When approaching embedded systems architecture design, several models can be applied to describe the cycle of embedded system design. The big-bang model: there is essentially no planning or processes in place before and during the development of a system. The code-and-fix model: product requirements are defined but no formal processes are in place before the start of development. The waterfall model: there is a process for developing a system in steps, where results of one step flow into the next step. The spiral model: there is a process for developing a system in steps, and throughout the various steps, feedback is obtained and incorporated back into the process.
Characteristics of Embedded Systems Must be dependable, • Reliability R(t) = probability of system working correctly provided that is was working at t=0 • Maintainability M(d) = probability of system working correctly d time units after error occurred. • Availability A(t): probability of system working at time t • Safety: no harm to be caused • Security: confidential and authentic communication Even perfectly designed systems can fail if the assumptions about the workload and possible errors turn out to be wrong. Making the system dependable must not be an after-thought, it must be considered from the very beginning
Must be efficient –Energy efficient –Code-size efficient (especially for systems on a chip) –Run-time efficient –Weight efficient –Cost efficientDedicated towards a certain applicationKnowledge about behavior at design time can be used tominimize resources and to maximize robustnessDedicated user interface(no mouse, keyboard and screen)Hybrid systems (analog + digital parts).