Is your USB product compatible with Microsoft Vista™?

Bernardo Elayda
Firmware Engineer
Nuvation

New PC’s can now be purchased with the Microsoft Vista operating system.  Vista has been developed by Microsoft from the ground up.  It promises improved performance, productivity, and security.  But, as with any new PC operating system, new issues (some would say old) will arise for legacy hardware products.  In particular, USB-based products may not perform optimally or may not work at all.

The typical issues of installation and operation may be encountered again as they did between Windows XP Home and Professional editions, Windows 98 and 98SE.  Many have seen USB products that will not install and/or operate on a newer version of Windows.  There will be 6 versions of Vista: Starter, Home Basic, Home Premium, Business, Enterprise, and Ultimate.  This will represent at least 6 use cases where an existing USB-based product may not install and/or operate.  Depending on how the hardware and software for your USB device was developed, a variety of challenges may arise.


Enumeration Failure

The first most dramatic issue that one can encounter with USB and Vista is enumeration failure. Enumeration is the process that happens when a USB-based device is first connected to a PC. In enumeration, the operating system attempts to identify and classify the USB device. If enumeration fails, the operating system will identify the device as an ‘unknown’ device. The USB-based device will be unable to operate and no installation of a driver will be possible.

A successful enumeration doesn’t mean that Vista has identified the device. The device may only be identified as a ‘default’ device. In this case, the device might not be identified as ‘unknown’ but as a generic device. Within the Windows operating system and USB definition, it is possible to classify a device as a generic device such as a hard drive, printer, keyboard or mouse. As a generic device, your product will have minimal functionality and no ability to access any of your products’ advanced features.


Driver Installation Failure

Once enumeration passes as the actual desired device, Vista may not be able to install your product’s USB driver.  In this use case scenario, the operating system has been able to identify the device.  The operating system will report the name of the device while it attempts to install its driver.  In this case, even if the location of the driver files have been explicitly identified by the user, Vista can report that it was unable to install the driver.


Mode Failure

If your product does enumerate and install the driver, it is possible that it will not operate in the desired HS or FS mode. HS stands for high-speed mode.  FS stands for full-speed mode.  HS mode is only possible for PC’s that have a USB 2.0 port.  In HS mode, the theoretical maximum data transfer rate between the PC and USB-based device is 480 Mbps.  In FS mode, the maximum throughput is only 12 Mbps, which is equivalent to the maximum throughput of a USB 1.x based product or USB 1.x hub.  During enumeration, the PC determines if it can connect at the maximum throughput.  If it can’t, the PC will operate the device at FS speed which can result in a dramatic reduction in throughput.

Conclusion

Existing operation of a USB-based product with Windows XP does not guarantee operation on Vista.  In addition, successful operation on just one version of Vista will not guarantee operation on other versions of Vista. Historically, this has happened with Windows 98 and 98SE, and with Windows XP Home and Windows XP Professional.  It is imperative to catch problems early, before they arise in the field, to avoid customer sat issues and returned goods costs.  Many companies are struggling with the engineering bandwidth required to test, update, optimize, QA, and WHQL-certify all of their USB products on the new Vista platforms.  Nuvation can help.

For more information on validating, upgrading, or designing your USB-based applications for the Microsoft Vista operating system, please contact Nuvation at sales@nuvation.com.


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* Windows, XP, and Vista are trademarks of Microsoft Corporation.