There are many correlations between good software designs and good software development processes. For instance, although there isn't one design that is applicable to every project, there are principles of good designs that are. The same is true in development processes. Also, it takes multiple views to adequately describe both software architectures and software development processes. One of the process views we will examine is a swim lane chart. This view highlights another parallel; good software designs limit the number of dependencies and interaction points between modules. Your process should as well.

We'll start with an introduction to the traditional waterfall, incremental and iterative development models. A quick overview of a classic formal process (DoD-2167a) will establish a common reference for what artifacts are typically created under a formal process. Other factors that add to a project's complexity, and consequently, the need for a more formal process will be reviewed.

By having a robust software design, a system can be more cost effective, faster to implement, and easier to maintain. Control software must also be structured to minimize the impact, and quickly recover from any effects of noise. Typically, noise affects a micro's ports and interrupt-registers, but the contents of any memory location can be suspect.

This paper/presentation explores some of the best practices for designing appliance control systems. It also introduces three views needed for an adequate description of a control's software architecture:
  • Design Overview diagram
  • Thread of Control diagrams
  • Data and Control Flow diagram

AHAM has published their "Connected Home Appliance - Object Modeling" standard. So now we are done, right? ...All the OEMs know exactly how to Internet enable their products and all the products will interoperate seamlessly.

A typical Internet enabled system will add at least three new elements to an existing appliance control system: a Network Interface, a Local Host, and a Remote User Interface. There are a variety of options available for each of the new elements, and numerous methods of interconnection.

What makes standardization so difficult is that, any of the new elements can be either a new physical device, or virtual functionality added to an existing processor. In other words, the system can be as simple as adding a TCP/IP stack and modem chip to an existing control, or as complex as adding a network interface card, a power line communications modem, a residential gateway, a web pad with RF communications, and a remote web site.

This paper/presentation will explore some design alternatives for internet enabling devices, including the pros and cons associated with the potential approaches.