Chapter 1 part 2 Embedded Computing High Performance

Topics n n Design methodologies. Methodologies and standards. © 2006 Elsevier

Design goals n n n Functional requirements: input/output relations. Non-functional requirements: cost, performance, power,

Aspects of performance n Embedded system performance can be measured in many ways: q

Energy/power n n Energy consumption is important for battery life. Power consumption is important

Cost n Manufacturing cost must be paid off across all the systems. q n n Hardest in small-volume applications. Manufacturing cost is incurred for each device. Lifetime costs include software and hardware maintenance and upgrades. © 2006 Elsevier

Other design attributes n n n Design time must be reasonable. May need to finish by a certain date. System must be reliability; reliability requirements differ widely. Quality includes reliability and other aspects: usability, durability, etc. © 2006 Elsevier

Design methodology n n Design methodology: a procedure for creating an implementation from a set of requirements. Methodology is important in embedded computing: q q q Must design many different systems. We may use same/similar components in many different designs. Design time, results must be predictable. © 2006 Elsevier

Embedded system design challenges n n n Design space is large and irregular. We don’t have synthesis tools for many steps. Can’t simulate everything. May need to build special-purpose simulators quickly. Often need to start software development before hardware is finished. © 2006 Elsevier

Design complexity vs. designer productivity © 2006 Elsevier

Basic design methodologies n n n Figure out flow of decision-making. Determine when bottom-up

Waterfall and spiral models © 2006 Elsevier

Modeling in hardware n n n Technology databases capture manufacturing process information. Cell libraries describe the cells used to compose designs. Logic synthesis systems use routability and timing models. © 2006 Elsevier

Hardware/software co-design flow © 2006 Elsevier

Platform-based design n n Platform includes hardware, supporting software. Two stage process: q q n Design the platform. Use the platform. Platform can be reused to host many different systems. © 2006 Elsevier

Platform design n Turn system requirements and software models into detailed requirements. q n n n Use profiling and analysis tools to measure existing executable specifications. Explore the design space manually or automatically. Optimize the system architecture based on the results of simulation and other steps. Develop hardware abstraction layers and other software. © 2006 Elsevier

Programming platforms n Programming environment must be customized to the platform: q q q n n Multiple CPUs. Specialized memory. Specialized I/O devices. Libraries are often used to glue together processors on platforms. Debugging environments are a particular challenge. © 2006 Elsevier

Design verification and validation n Testing exercises an implementation by supplying inputs and testing outputs. Validation compares the implementation to a specification or requirements. Verification may be performed at any design stage; compares design at one level of abstraction to another. © 2006 Elsevier

Design verification techniques n n n Simulation uses an executable model, relies on inputs. Formal methods generate a (possibly specialized) proof. Manual methods, such as design reviews, catch design errors informally. © 2006 Elsevier

A methodology of methodologies n Embedded systems include both hardware and software. q n HW, SW have their own design methodologies. Embedded system methodologies control the overall process, HW/SW integration, etc. q Must take into account the good and bad points of hardware and software design methodologies used. © 2006 Elsevier

Useful methodologies n n n Software performance analysis. Architectural optimization. Hardware/software co-design. Network design.

Joint algorithm and architecture development n n Some algorithm design is necessarily performed before platform design. Algorithm development can be informed by platform architecture design. q q Performance/power/cost trade-offs. Design trends over several generations. © 2006 Elsevier