There’s a ground swell of “green” requirements taking a prominent position in modern electronics design. But there are some substantial benefits that can be obtained from improving energy efficiency that’s all wrapped up in the green part of the design. By selecting the right processor and systems software you can eliminate active cooling devices, reduce power supply needs, and reduce real estate requirements.
There are many applications that benefit from fan-less operation such as wireless routers, mesh routers, “brick” style embedded systems and a wide variety of applications that can be serviced by Single Board Computers (SBC). ADI Engineering’s (1) Cinnamon Bay SBC and their customizable Atom E6xx-based design is one example of how fans and other active cooling devices can be eliminated from an embedded system. Eliminating cooling fans reduce cost, improve reliability and cut systems size. While some of this reduction in cooling needs comes from careful SBC design, much of the reduction in power consumption in comparison to other processor-based solutions, comes from the intrinsic capabilities of the Intel® Atom™ E620 processor. The E620 thermal dissipation requirements may be met using a thermal management interface materials (TIM) and a heatsink. Together the TIM and heatsink serve to keep the temperature of the semiconductor circuit junctions from either causing the processor to temporarily stop working or fail completely. Intel provides a Thermal Design Guide that details options for heatsink alternatives.
Intel’s Atom processors include a Thermal Monitoring feature that can help control the processor temperature. When the Monitor is enabled and active due to the die temperature reaching a pre-determined activation temperature, the Enhanced Thermal Control Circuit (TCC) attempts to cool the processor by first reducing the core to a specific bus ratio, then if necessary stepping down the internal operating voltage. Both of these actions will have an impact on processor performance – and therefore the embedded software.
ADI Engineering takes a standard Atom-based SBC into the realm of fully customizable designs. By using ADI Engineering’s Intellectual Property licensing mechanism, designers can further reduce both power consumption and board size by eliminating unused capabilities of the Cinnamon Bay SBC. According to the company, the real estate requirements can be reduced up to 50% compared to the COM Express Ultra form factor. The Ultra is 55 x 84 mm making the customized Atom board a very small device.
Advantech(2) offers a "SOM-6764” COM Express (95x95 mm) module that can be populated to large scale embedded systems: supports on board 1 GB DDR2 memory, PCI, 1 PCIe x 1, 1 SATA, 1 IDE, 6 USB ports. In this type of configuration power consumption may be dictated more by the duty cycle of usage for peripherals and memories rather than the processor itself. The Advantech SOM-6764 uses standard AT or ATX style power plugs and supplies. Other Intel Embedded Alliance members offer similar COM Express boards, including Emerson (3) and others detailed in a report hosted on the Intel Embedded Community.
Kontron(4) offers custom development of embedded boards based on the Intel Atom family. When developing a custom board, pre-existing board products can be used to prototype embedded systems, but once a system has been proven, extraneous bits and pieces may be eliminated. Doing so lowers per-unit costs, while optimizing board real estate and power consumption.
Improving energy efficiency often goes hand in hand with reducing power consumption. But such is not always the case. For example, there are algorithms that are energy efficient, but which don’t necessarily allow an embedded device to operate within a specified instantaneous power budget. So it’s possible for short durations of power consumption to be more energy efficient over the long term. This mostly happens when devices peripheral to the processor are used intensively at the same time that high power draw instructions are executed. For embedded devices that must keep instantaneous power consumption below a threshold, the power limitations may require the use of a less efficient algorithm – but one that uses more power to complete the computation.
Software Tools from Green Hills (5) and Wind River (6) can assist with optimizing embedded systems software with an eye towards energy efficiency. Software-only tools such as Wind Rover’s Run-time analysis tools: System Viewer, Memory Analyzer (formerly MemScope), Performance Profiler (formerly ProfileScope), and Data Monitor (formerly StethoScope) can be used to gather secondary information about how much energy is being used by a candidate embedded system. The secondary information relies on knowing how much time is being spent in various portions of the application code. When combined with JTAG-based in-circuit-emulation tools and fast-response current metering instrumentation, it’s possible to build a tool suite that permits you to monitor actual energy usage, and therefore be able to determine energy efficiency.
Measuring actual energy consumption is an evolving field that today has to be accomplished by collections of tools. The time units of measurement and the intervals depend primarily on any restrictions on instantaneous power consumption. This is especially the case for Power over Ethernet (PoE) powered devices. For some systems you can add additional power sources to your design by adding capacitors or batteries that are engaged when the embedded system reaches a pre-set current consumption. Recharging the secondary power source occurs when the embedded application is consuming lower levels of power. Of course, the size of these secondary sources may add substantially to the physical size of the embedded electronics.
Saving board real estate is often a natural outcome of improving power efficiency. If we eliminate a fan from an embedded system, there is a savings of the fan size, power connections to the fan, and a reduction in the required power supply. A reduction in the energy required to operate an embedded system impacts the power supply design. If we reduce the energy consumption by 50% this usually translates into more than a 50% reduction in power supply size. For embedded systems that include the power supply as part of an SBC, the reduction in board space can become significant: smaller boards may mean a smaller enclosure which in turn means lower costs; smaller boards can have a lower cost to build beyond just the raw board costs based on test costs and lower manufacturing losses; lower power requirements may allow wiring to be reduced in size which may save costs; and improved energy efficiency can extend product life by improving reliability.
Improving energy efficient is a net win for manufacturers, users of embedded systems, and the power grid as a whole.
How can you improve your product’s energy efficiency?
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- ADI Engineering is an Associate member of the Intel Embedded Alliance
- Advantech is a Premiere member of the Intel Embedded Alliance
- Emerson is a Premiere member of the Intel Embedded Alliance
- Kontron is a Premiere member of the Intel Embedded Alliance
- Green Hills is an Affliate member of the Intel Embedded Alliance
- Wind River is an Associate member of the Intel Embedded Alliance
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Intel® Embedded Alliance