This “Product How-To” article focuses how to use a certain product in an embedded system and is written by a company representative.
In 1995, long before the ETX form factor and the COM Express standardevolved, DIGITAL-LOGIC developed the first Computer On Module (COM). Atthat time, a bonded Pentium MMX166MHz with a bonded chipset was placedon a module (60 x 68mm).
All subsequent COMs increased in size, culminating with the extendedCOM Express (110 x 155mm). Intel's energy-saving Atom, a chipsettogether with a CPU, offers interesting possibilities for embeddedcomputer applications (Table 1, below ).
The Atom offers new interfaces and does away with parallel bussystems (ISA, PCI); it is suitable for battery-operated and fanlesscomputer systems. Miniaturization using mini-BGAs with 0.4mm pitchdistance requires the use of more expensive HDI printed circuit boards.
|Table1. Atom signals and COM Express requirements|
The new smartCore Express format is the size of a business card (58x 65mm, height = 11mm) and possesses a 220 pin connector link to theprinted circuit board as well as a standardized thermal interface(Figure 1, below). This allows operation in an extended temperaturerange of -40 up to +85 degrees Cetigrade.
At the same time, the CPU, DDR2 memory (up to 2GByte) and thechipset are glued to the PCB by means of underfilling so that thesmartCore Express module will be resistant to vibration and shock.
An ordering option is a solid-state drive with 4GByte capacity whichallows booting from a fast flash drive. Other embedded computermanufacturers already offer a compatible second source for thesmartCore Express.
|Figure1. An open SMA200 unit|
The smartCore Express consolidates the minimum number of interfaceswhich are available from the Atom5x0 with the US15W chipset. Thecustomer can achieve all expansions on the printed circuit board (i.e.,LAN, sound, FireWire, VGA, and PCI32bit).
There is always the possibility of incompatibilities with an Atomdesign on a COM Express module since some signals from the Atom are notmade available. Be very careful when onboard functions such as LAN andSATA reduce the number of available free PCIe lanes to almost 0,respectively through the use of PCIe switches the bandwidth of theduplicated PCIe lanes are reduced.
Implementing the Atom design on a smartCore Express module gives avery small and cost-effective printed circuit board (Figure 2 below ). The same 220pinconnector is used as on the COM-Express. This has the advantage thatthe connector is available for longer and can be manufactured in largequantities.
|Figure 2. The SMA200 with the 1.6 GHz Atom CPU and up to 2 Gbyte of DRAM|
The module is screwed on to the carrier board with 4 bolts. All thefunctions of a normal PC can be found on the module including a robust,soldered-on 2Gbyte memory, a bootable solid-state disk and all voltagegenerators. The module only requires 5Volts with a typical power inputof 5 Watts.
The cover has 4 threaded holes to allow the module to be mountedonto a casing or to mount a passive cooler onto the module. ThesmartCore Express is small enough that it fits onto a standardPCI/104-Express card.
It leaves space so all the necessary bridges and controllers can befitted which allows the availability of the functions SATA, PCI32bit,LAN, COM1-4, LPT, back-up battery and PCIe mini-card on a space of only90 x 96mm. Peripheral expansion is done using the PCI-bus (up to 4cards) or via the high performance PCI/104-Express bus (up to 4 cards).
PCI/104-Express boards fitted with the latest energy-efficient IntelAtom processors allow for passively cooled operation in the extendedtemperature range of -40 up to +85 degrees Centigrade.
To simplify the development phase, DIGITAL-LOGIC offers adevelopment kit containing all necessary information, diagrams, tools,implementation guide and support.
Table 2 below shows acomparison of the other COM products on the market which make use ofthe new, energy-efficient Atom from Intel. The large variations of thefunctions makes the COM Express solutions less compatible and, prior toeach application, the user must find a compromise between functions andnumber of PCIe lanes.
The Atom based COM Express products are not truly compatible withthe previous COM Express products (915 / 945 / 965). From thecustomer's point of view such implentations do more harm than good.
|Table2. A comparison of COM products which use the Atom CPU from Intel.|
Every additional function (i.e., LAN, SATA, VGA, PCI32bit) on theCOM raises the power consumption approx. 1 Watt. Since future Atomgenerations/variations will presumably again include LAN and willprobably only have SATA interfaces, the smartCore Express already hasreserved pin definitions for just such changes.
Additionally to the COM Express definition, the smartCore Expressconcept has extra connector pins for SSD/MC cards, SDVO and SPIsignals. All technical information for the new smartCore Expressspecifications and for Atom-based embedded computer products may bedownloaded free of charge at www.digitallogic.com.
Felix Kunz is the Chief ExecutiveOfficer at DIGITAL-LOGIC AG.