Chapter 8 PDF

Top-Down Design with UML for Microprocessor-Based Product Development

• Microprocessors must be programmed before they can perform any task, and their development tends to be costly.

• Microprocessors offer opportunities for product features that are not achievable by other means.

• Testing microprocessor-based systems is a significant challenge as both the software and hardware need to be extensively tested.

• The electronics industry trends towards shorter product life and higher performance over price ratio, hence the need for improved design methodologies and investment in tools and resources.

• Product design is a human process that involves communication, creativity, negotiation, and agreement among system designers, clients, and third parties.

• The waterfall approach to system development involves clients formally agreeing on a requirements document, designers developing a design, and implementing the system, followed by endless maintenance. Modern ideas move towards the iterative method, which consists of developmental cycles with each cycle making up of analysis, design, and implementation.

• The Unified Modeling Language (UML) is a language for specifying, visualizing, constructing, and documenting the features of systems, and it represents an important part of system development process.

• The first stage in both the iterative and waterfall methods is requirements gathering, which involves obtaining from the customer a description of the product's intended functions.

• Two reasons why requirements gathering is necessary are to avoid 'creeping featurism' and 'missing features.'

• System analysis includes subsystem identification, dynamic modeling, and feasibility studies/simulation.

• System specification is the overall controlling document in a project and includes a complete description of what the system should do, the performance requirements it must meet, specific details of the operator/system interaction, procedures for error handling and diagnostics, constraints on the design and development project, and goals to aim for in the design.

• Designers need to make decisions on build or buy ready-made parts, choice of microprocessor, and software vs. hardware. Factors to consider when choosing a microprocessor include cost, software availability, experience of others, development tools, processor capability, and recurring production costs.Top Down Design of Embedded Computer Systems

• Top-down design is a method of designing computer systems by breaking them down into smaller subsystems.

• System analysis is the process of identifying the requirements and constraints of a system.

• The Unified Modeling Language (UML) is used to specify, visualize, construct, and document the features of systems.

• UML diagrams are designed to let developers and customers view a system from different perspectives and in varying degrees of abstraction.

• System integration is the process of bringing together individually designed and tested subsystems to form the full system.

• Testing during the production stage is different from testing during the development stage and requires special test jigs and procedures.

• The use case diagram is a UML diagram used to express user requirements.

• Interaction diagrams demonstrate how subsystems collaborate with others to complete tasks.

• A prototype is the initial version of the system and is used to demonstrate the validity of the system design.

• Hardware testing should be done on each subsystem basis using simple programs designed to fully test out the hardware.

• Software testing must be done to verify that the software functions correctly and does not cause errors later in the project.

• The transition from a prototype to a manufactured product may involve changes in the original design to reduce assembly costs and ensure that the system can be assembled and tested by relatively unskilled staff.