The software development must first begin by deciding how to implement the CEBus/Home Plug & PlayTM protocol stack. Two options exist here: the developer can either write the stack themselves, which is a long and arduous process taking several man-years, or purchase a tool that integrates the protocol stack with their code.

CEBus Design

Evan Price | Domosys Corporation

Product Development Flow
Using Domosys HeadStart Suite
By Evan Price, President, Domosys Corporation

The software development must first begin by deciding how to implement the CEBus/Home Plug & PlayTM protocol stack. Two options exist here: the developer can either write the stack themselves, which is a long and arduous process taking several man-years, or purchase a tool that integrates the protocol stack with their code.

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Domosys HeadStart Suite


Domosys has combined its industry-leading development into one very low-cost bundle called the HeadStart Suite. For only $995, developers have everything they need to go from concept to a functional CEBus® and Home Plug & Play™ compliant prototype. This package includes a license for the CEBox™ software development system, a CEBoard™ prototyping platform, a license for the CETester™ tool and a CECom™ power line modem.

This article describes how successful developers use this suite of tools in combination with domosys products and services to create winning designs.

Domosys Development Process

Hardware and software issues must be considered in parallel during the development process of network products.

The hardware development process starts with the selection of the desired transceiver. The transceiver is the main hardware component that gives a stand-alone product networking capabilities. Domosys offers two transceivers, the CEWay™ PL-One, and the CEWay PL-III. Both transceivers use a spread spectrum signal over the 100-400 kHz band as specified by the CEBus® Standard. The PL-One integrates the CEBus physical layer, including an advanced DSP, and an 8052 microcontroller. It is an excellent choice for low-cost applications, such as light switches, since the controller can run both the protocol and the application code. The PL-III integrates both the CEBus physical and data link layers, and includes the same advanced DSP as found in the PL-One. It is used in applications with dedicated 8 or 16-bit microcontrollers. Serial or parallel interfaces are available to connect the transceiver to the host microcontroller.

Once the transceiver is chosen, the developer must select an approach regarding the analog components that interface the transceiver to the power line. Domosys offers low-cost SIP cards – the DomoSIP for the PL-III and the Interface SIP for the PL-One - that integrate all the amplification and filtering components needed. SIPs are effective when the finished product is manufactured in small batches of a few thousand of units. Beyond those volumes, it is recommended to place all components directly on the main circuit board.

When choosing memory for the design, the developer must decide whether the protocol stack and application code should best reside in flash, non-volatile or standard memory devices, and what size of memory is required. This will depend on the product specifications; for example, does the firmware for this product need to be upgradeable from a remote site? Finally, a power supply and power coupling components are required to complete the hardware design of the node.

The software development must first begin by deciding how to implement the CEBus/Home Plug & PlayTM protocol stack. Two options exist here: the developer can either write the stack themselves, which is a long and arduous process taking several man-years, or purchase a tool that integrates the protocol stack with their code. Domosys strongly favors using tools because (a) the time and money saved is enormous, (b) the risk associated with non-compliance to the specifications is greatly reduced, (c) the cost of the tools is insignificant, and (d) the tools are supported by experienced technical support personnel.

Using a tool-based development flow, the design work begins with the CEBox™ software development system. This tool models the product’s features into protocol objects. This product modeling is based on CEBus contexts and objects, and its Common Application Language (CAL). CEBus specifies context and object classes for every known home networking market segment, such as lighting, security, and environmental control. This is one of the CEBus Standard’s most powerful features. CEBox also comes with 8051 and 68HC11 libraries which implement a CEBus-compliant protocol stack and Home Plug & Play services. These libraries are known as CELib™ . A small portion of each library is dedicated to supporting different transceiver choices, such as the PL-III or the PL-One. With CEBox, the developer customizes the protocol stack according to the product specification by choosing desired protocol parameters and services, such as the Addressed Acknowledged data link layer service. CEBox also provides tools to manage the user application code files. When the creation of the protocol and the application code is completed, the resulting "C" code is compiled using an IAR compiler and downloaded to the CEBoard prototyping platform in object code form. The compiled protocol and application code size for a CEBus / Home Plug & Play compliant product is approximately 32K of ROM and less than 1K of RAM.

The third step, creating a functional prototype, can be accomplished using a CEBoard platform. There are CEBoard versions for the three microcontroller families, CEWay PL-One, 8051 & 68HC11, supported by Domosys protocol libraries. This versatile hardware platform includes several peripherals such as buttons, an LCD, battery pack, real time clock, non-volatile memory, a buzzer, an RS-232 port and a prototyping area. The RS-232 port can be used to download the compiled protocol and application code from the CEBox software running on a PC. The combination of this code with the hardware available on the CEBoard represents a functional prototype of the product being developed. In some applications, this stage may be reached within a matter of days. This gives the developer plenty of time to perfect the product design according to the results of real physical tests and demonstrations.

Once the prototype is developed, the next step is to test it with the CETester tool. This software tool, in combination with the CECom power line modem, monitors and analyzes communication traffic on the power line. It also runs scenarios that verify the product’s functionality relative to a test plan, and validate its conformance to the protocol specifications. Developers can define scenarios, group them in categories and re-use them any time to verify compliance. Once prototype testing is completed, and a printed circuit board is laid out, production can start. The same CETester scenarios can be used for final integration and tests, formal qualification and production line testing.

When the product is completed, it is sent to the CEBus Industry Council’s (CIC) Plug Lab for conformance testing. This conformance test facility, created in partnership with Purdue University and located in Indianapolis, is fast becoming the leading site for testing home network products of any protocol. When it passes the protocol conformance specification, a favorable report is issued and the product may carry the official Home Plug & Play logo to help consumers identify interoperable products.

The last step to reach the end-user is the product installation. Although simple products can be installed by the home-owner, more complex installations involving several products installed at once will benefit from an installer. The DomoNet tool assists the installer in qualifying the power line network in the chosen environment. The DomoNet is a hand-held receive/transmit module that computes the success rate of communication between sockets, or other access points to the power line, in a building. It provides results in real time and over extended periods of communication, and supports different Data Link Layer (DLL) services.

To assist the development process, Domosys offers technical support on our tools. We also offer training sessions, known as DomoU™ , on topics related to protocol basics, working with Domosys tools and perfecting the design flow from idea to finished product.

An alternate development flow is suggested for developers that are not yet familiar with the CEBus and Home Plug & Play standards, who need a very rapid development cycle, or who do not currently have the resources available to develop the product internally. Domosys offers design services to provide assistance in these areas, which many manufacturers have benefited from. Not only does this eliminate almost all the risk from the development process, but it is the best route for most companies to learn enough about CEBus and Home Plug & Play to be able to take on future products themselves.

For more information, visit: www.domosys.com


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