Selecting the Right Computer on Module Vendor

By Maheshwari

Introduction
Engineers have always been faced with the question of whether or not a Computer-on-Module (COM) company is the right vendor to partner with. To help with the decision, I have written an article to help engineers select the ideal COM partner.

Target Usage
First, it is important to identify the applications for which a Computer-on-Module will be used for. Engineers have a range of applications and want to have the computer on module working across different applications. Obviously, engineers prefer not to develop expertise with several different COMs. To avoid this situation, engineers need to focus on the target applications. Think about the applications that will most likely be deployed in the next couple of years and determine if the COM will work with the apps. Once this is done, short list the vendors that can provide the COMs that meet the requirements.

Life Time
Some applications like defense require a product life-time of ten years. It would not be unusual for customers to order a few thousand additional units after seven years of production. This is one of the challenging issues that a module manufacturer faces — the dependence on the processor manufacturer for the life of the final product. Unless the processor manufacturer is committed to a processor, there is no guarantee that the manufacturer will continue the production of the product. The processor has to be supported with huge volumes to stay in production. With the silicon manufacturing process improving at break-neck speed, the fabrication technology of today becomes obsolete the day after tomorrow. As a result, older processors using older fabrication technology are difficult to produce or tend to be costly in the long run. It would be too much to ask the module manufacturer for a life-time of ten years. However, engineers should ask the vendor if they will be willing to provide a pin-to-pin compatible module with similar capabilities once the life of the board has ended.

Support
Support of the module is one of the most important things to consider in the selection of a Computer-on-Module vendor. Engineers should visit the vendor’s website and look for support documentation for the board. For engineers designing a custom baseboard using a COM, having a set of application notes on the usage of the COM from the COM company would be of great help. Old documents that have not been updated is a sign customer support is not important for the vendor. Another feature to look for is a ticketing system for dealing with problems and answering questions engineers may encounter when they design custom carrier boards around the COM. Design support is another feature to look for. Engineers need to determine if the COM vendor is backed up by a solid design team that can support a custom design — such as custom carrier board schematics review (some companies offer free support for a carrier board schematics review). Before selecting a COM vendor, engineers should ask what type of support will be provided.

Reference Designs
Most manufacturers offer reference design for the chips they manufacturer. This will help significantly with custom designs. As part of the selection process, engineers should check the availability of the design materials of the reference designs from the COM manufacturer. The availability of design materials such as schematics and PCB layout files of the daughter board from the COM vendor are helpful — especially for designing a daughter board with a vendor’s COM.

Design Services
Sometimes it is helpful if the Computer-on-Module company also offers design services. This might be an important point if engineers do not have time to build the carrier board or the base board and they need the COM vendor to do it. Questions to consider are:

  • If software customization is required, does the COM vendor have the ability to help with the customizations?
  • If the COM company is small, will they be able to complete their part of the project on time?
  • If the board vendor has a large resource pool, will they be willing to provide resources for software customization?

Partner Status
If a design involves WinCE, Windows XP Embedded, or Windows Vista Embedded, developers should ask if the vendor have achieved Gold Partner accreditation status. This might also be helpful for design services like driver development and application development.

BSP Quality
Regardless of the operating system (OS), engineers need to know if the board vendor can provide enough documentation of the BSP features. Before selecting a BSP, engineers should ask for release notes to reduce the amount of time debugging the BSP. Engineers need to read the release notes carefully to determine if the BSP can meet the final product specifications.

BSP Source
In my opinion, engineers need access to the BSP source when debugging the drivers or when more code needs to be added to the OAL layers in WinCE. This may not be needed for most of designers, but having the option to license the source IMO is an important factor. Engineers should ask the COM company if they are willing to do that.

Sample Applications
Engineers should check whether the evaluation board have sample applications for the peripherals of interest. If C is not a strong point, then Linux may not be the option. If C is a strength, engineers can choose Linux as the OS. On the other hand, if C# is an option, then Windows CE with .NET compact frame work is the better choice. Engineers should ask the board vendor if they offer application for the .NET compact framework.

Pricing
Obviously, the pricing of the module is a key factor. Other than pricing of the module in various volume categories, engineers need to consider:

  • What is the cost of loading the target image into the COM during production? This is often missed and it is better to discuss this up front with the COM manufacturer. Companies may want to load the target applications in order to ship directly from the factory. This might also reduce the application loading cost. Engineers should talk to the vendor about loading the kernel, file system, and application binaries with the modules during production. There are hidden costs and the cost of the module should be calculated on the basis of this.
  • Does the COM vendor offer runtime license loading on the module? This saves time and reduces cost.
  • What is the cost of reviewing carrier board schematics? Some COM companies provide the service for free. If a vendor is charging for it, then it needs to be added to the price of the module.
  • What is the cost for support? Engineers cannot discount this cost and need to factor this in too.

Pricing is a very important factor. However, at the volumes that COMs are procured, the unit price does not have a major impact. Choosing the lowest cost COM that is not supported well or supported at exorbitant cost, would be disastrous to the engineer that is planning to use the low cost module. With the goal of getting the product to market faster using the COM, engineers need to understand that even though the module cost is marginally higher, the support (even paid-support) availability is more important than a rock-bottom cost COM with little or no support.

Maheshwari is the head of product design services at e-con Systems