Instrumentation • Electronics
The widespread availability of USB flash drives and SD cards makes consumer memory a convenient option. Most users are already familiar with their operation, and it is easy for OEMs and end users to obtain these devices from electronics retailers.
Another issue to consider is the need for high memory
capacity. Transferring data to and from embedded systems often only requires kilobits or megabits of memory capacity, but the higher capacities available in consumer memory devices may be required in some cases. Video logging, for example, can require gigabytes of memory capacity. However, some OEM memory devices are now offered in memory capacities of up to 32GB, so finding devices with high memory capacities is no longer limited to consumer memory. In terms of costs, the upfront cost-per-bit of most
consumer memory devices is relatively low. But if an OEM application requires thousands of portable memory devices over the life of the design, then the expenditure over the lifetime of the application is considerable.
will work in an OEM device and others won’t. A lack of control over which devices will work can increase support costs and can be inconvenient for end users. One must also bear in mind that technology standards
change. The transition from SD to SDHC is a recent example. A system designed to use SD cards prior to the release of SDHC will not work with SDHC cards unless the system’s firmware is updated. Likewise, the fast-changing consumer electronics market virtually guarantees that a new technology will emerge in the future, bringing with it new compatibility issues. Finally, using a consumer memory device may increase the
risk of data theft. A misplaced or stolen USB flash drive is not protected from an unauthorised user accessing contained data from a PC, for example. Similarly, using a USB receptacle in an embedded design allows any USB flash drive to plug in, which can increase the risk that information could be pulled off the system or that a virus or other piece of malware could be transferred to the embedded device. Another drawback is that most consumer memory devices
today start at 1GB or higher. As such, embedded systems that require only kilobits or megabits of memory to perform a desired task are essentially paying for capacity they don’t need. While not always apparent in the early stages of the design
process, these considerations should be examined before deciding whether consumer memory meets both the design criteria and the expected use.
Specialist OEM focussed memory
Non-consumer, OEM systems are usually manufactured and designed to last years. As a result, portable memory used in these systems must provide long-term availability and reliability. The environmental conditions in which OEM designs operate can be demanding as well, and there is often an increased emphasis on secure access. Requirements that are unique to OEM designs illustrate why consumer memory devices’ light-duty construction, low cycle life connectors, lack of security features and short product life cycles can be detrimental to non-consumer applications. Rugged construction is another characteristic required by
Fig. 2. A data key from Nexus GB in use on a Klixkey application for beverage vending.
Handheld embedded designs often require a small portable memory device to fit in the system. In these applications, a microSD card may be the most attractive option due to its small size. Equally, some designs may actually require a larger portable memory device. For example, a memory token must be able to be easily inserted and removed by a user wearing arctic gloves in certain military applications. As you can see, while consumer memory products are not
explicitly designed for OEM designs, they do offer unique benefits. However, these benefits may also have unintended consequences. With hundreds of different models of consumer memory
products available, OEMs can’t possibly test, approve and support every device that physically fits. Despite memory manufacturers’ attempts to ensure compatibility, some models
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OEM applications, especially for use in harsh environments. Some outdoor applications such as the ones used in the military, construction or agriculture sectors, use portable memory devices to transfer operation and maintenance data between the base and vehicles in the field. The memory device may be exposed to vibration, dirt, moisture, shock, extreme temperature and rough use. Light-duty consumer memory devices and receptacles do not provide sufficient protection or the environmental ratings needed for harsh environments. Frequent use and long-lasting designs require durable
connector systems. Vending machines, for example, may use portable memory to provide cashless vending in non- networked environments. A customer can use the memory device to purchase merchandise from the machine, such as snacks, drinks or even industrial supplies. These machines often see 50-60 cashless transactions per day. Rated at just 1500 cycles, a USB mating receptacle could wear out in as little as 25-30 days. Furthermore, many OEM applications require increased
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