Five years ago, ready to go reference platforms were few and far between within the distribution arena and were typically reserved for only the most expensive of application specific end-equipment. Since then, however, the need to provide end customers with more flexible, cost effective development platforms encompassing both the hardware and software aspects of the complete system design have accelerated the proliferation of reference platforms. The SnakeBytes reference platform from EBV demonstrates how a flexible board level design can easily provide complete, custom made system solutions with minimal engineering effort. With its flexible architecture, this platform can be used in a wide range of high-end industrial emerging applications within medical imaging systems, networking and communication applications, wireless LANs, network storage, home network appliances, and industrial control.
SnakeBytes system partitioning
SnakeBytes is a high-end industrial applications reference platform featuring a board-level, modular development environment allowing system developers to leverage the power and performance of Altera Stratix-II FPGAs alongside Freescale's PowerQUICC-II processors with the peripheral support from a number of National's high performance analogue offerings. The package itself is capable of providing a number of capabilities. It can extend I/O capabilities with additional analogue technologies and interfaces which are normally not present within a PowerQUICC-II derivative. It provides accelerating computation intensive algorithms in hardware to support data pre-processing and accelerate the overall system performance. What's more, the modular approach allows future system performance upgrade to follow development needs.
The SnakeBytes platform offers a Linux board support package (BSP), a PCI solution for high data throughput to the FPGA and/or a Local Bus interconnect (LB) solution for low-latency data transmission. The local bus platform features Freescale's MPC8349E PowerQUICC-II processors with clock speeds scaling to 667MHz and integrating advanced features such as DDR memory, dual 10/100/1000 Ethernet MACs, dual PCI and hi-speed USB controllers. The PCI solution for high data throughput enables the PowerQUICC-II and Stratix-II combination to connect between each other and share access to peripherals such as RS-232, CAN, LCD controllers and industrial Ethernet physical interfaces.
SnakeBytes I/O modules
The choice of using either an LB or PCI bus connection between the processor and FPGA depends very much on the designer's system partitioning requirements with the choice of modules being highlighted below.
PowerQUICC Pro module
In addition to the features previously mentioned on the MPC8349E PowerQUICC-II processor, an integrated security engine derived from Freescale's security coprocessor supports DES, 3DES, MD-5, SHA-1, AES, and ARC-4 encryption algorithms, as well as a public key accelerator and an on-chip random number generator. The security engine is capable of single-pass encryption and authentication, as required by IPsec, IEEE 802.11i standard and other security protocols.
Industrial A/D Module supporting 1.1GHz bandwidth
Using two high performance ADC14155's from National supporting 14-bits resolution and 155Msps sampling rate, this module is the high-speed data acquisition link that feeds the on-chip FPGA RAM. Control registers are available to adjust the sampling frequency, start the acquisition of a given number of samples and control the "sampling ready" flag. The ADC14155 uses a differential, pipelined architecture with digital error correction and on-chip sample-and-hold circuit to minimize power consumption and external component count. Yielding a full-power bandwidth of 1.1GHz while providing excellent dynamic performance, the ADC14155 operates from dual +3.3V and +1.8V power supplies and consumes 967mW. Having a separate +1.8V supply for the digital output interface allows lower power operation with reduced noise and the power-down feature reduces the consumption to 5mW with the clock input disabled. The differential inputs provide a full scale differential input swing equal to 2 times the reference voltage with the option of using a stable 1.0V internal voltage reference or an external reference. Clock mode (differential versus single ended) and output data format are pin-selectable. A duty cycle stabiliser maintains performance over a wide range of clock duty cycles and over an industrial temperature range of -40 to +85°C.
ADCs that sample more than several hundred megahertz typically have input bandwidths that are limited to no more than their maximum sampling frequency to improve noise performance. It is this limitation alone that can rule out certain ADCs from applications where the input spectrum bandwidth demands are higher and particularly in applications using high speed PowerQUICC-II and Altera Stratix-II FPGAs. With an on-chip 1.1GHz full-power-bandwidth amplifier on the ADC14155 it helps increase dynamic performance significantly and supports more precise capture of fast analog data at extremely high conversion rates which are ever present in high speed networking and medical applications.
Industrial 10/100Mbps Ethernet module supporting copper
With the PowerQUICC-II supporting dual integrated 10/100/1000Mbps Ethernet Media Access Controllers (MACs) the physical interface to the internet using the DP83848 and DP83849 from National is ever present. The 10/100 PHY DP83848 features an Energy Detection Mode (EDM) which is an effective power saving technique offering major system performance advantages and in low power state it consumes only 20mW and will only waken up from sleep mode if it detects energy on the transmission line medium. Energy detection thresholds can be set via a control register to prevent line noise causing unwanted signal detection. Occasionally, the PHY will waken to send out short energy detect pulses as a safety check to ensure that there are no other PHYs attempting to carry out the same EDM activity on the line. The AutoMDIX feature of the DP83848 also allows the use of straight through CAT-5 cables or crossover cables and eliminates the possibility of improper cable connection or when a straight-through cable is required during field installation. In addition to low power, the DP83848 is optimised for cable length performance far exceeding IEEE specifications. There is also a 25MHz clock out allowing applications to be designed with a minimum of external parts, which in turn results in the lowest possible total cost of the solution. The DP83848 easily interfaces to twisted pair media via an external transformer and fully supports JTAG IEEE specification 1149.1 for ease of manufacturing. With both MII and RMII interfaces supported the flexibility of the design makes this part suitable for a range of commercial and industrial temperature specifications.
The link quality analysis capabilities of the DP83848 using the on-chip Time Domain Reflectometry (TDR) are intended to provide end equipment manufacturers with a product that is more intelligent to predict line trouble before degradation to the point of failure. The TDR implementation sends out a pulse on either the receive or transmit conductor pair and by determining the strength of the reflections using software it can detect such events as cable shorts/opens, distance to the fault and pair skew. Real-time continuous dynamic monitoring of the link quality using the SNR estimator also allows the system to take corrective action again saving lengthy downtime and costly repairs.
Industrial 10/100 Ethernet module supporting fiber optics
As the demand continually increases for more maintainable hi-end industrial network management solutions or indeed any type of sophisticated communications equipment, it is envisaged that future solutions will need to cope with far higher administration, cable diagnostics and monitoring tasks. To address this need, National developed a new robust dual 10/100 Ethernet PHY (DP83849) which is not only cost effective to implement but offers a more highly optimised physical interface to satisfy the needs of industrial and medical networking equipment The DP83849 includes support for fiber, flex-port switching and enhanced cable diagnostics. It interfaces directly to the MAC blocks of the PowerQUICC-II through the IEEE 802.3u-compliant MII or RMII interfaces. It also features Auto-MDIX, transparently allowing the end user to use straight or cross-over cables. It also includes the same energy detection circuitry found on the DP83848 for intelligent power management to increase system reliability. Featuring a flex-port technology, the DP83849 allows the two ports to provide fully integrated range extension, redundancy or repeater mode, media conversion from fiber to copper and a hardware based failover to guarantee uninterrupted network operation and port monitoring. With error free operation over 137 meters, this easily extends the current IEEE 802.3u specification of 100 meters. The DP83849 interfaces to the fiber using an external 10/100/1000Mbps transceiver from Avago Technologies (AFBR-5978Z). This fiberoptic transceiver comes with digital diagnostic monitoring interface (DMI) and with increasing data rate throughput operating over Plastic Optical Fibre (POF), the DMI permits real-time monitoring of transceiver performance and system stability, resulting in higher factory network uptime. Coupled with the enhanced cable diagnostics and the industrial temperature range of the DP83849, it all combines to make this module well-suited for implementation in factory floor and building automation applications.
Additional add-on modules
Other add-on modules available today include a communication module with physical drivers for dual CAN, quad RS-485 and single RS-232 interfaces, a 32-bit 128MByte SDRAM module, a 2MByte Fast SRAM and 8MByte Flash module, a flash module with 192Mbytes of NOR Flash, DVI input and output modules with standard DVI connectors, and a TFT LVDS interface with inverter power supply and touch screen controller.
Future modules enabling system upgrades
The recent addition to National's Ethernet product portfolio of the IEEE-1588 time stamped 10/100 PHY (DP83640T) is a good example of how customers can upgrade to future Ethernet module replacements within the SnakeBytes platform. For end equipment where the issue of network clock synchronisation is becoming ever present the DP83640T is the latest high precision PHY designed for real time connectivity with deterministic, precision clock synchronisation. The very low transmit and receive latency coupled with the dynamic monitoring of link quality during normal operation assessing fault prediction is essential in cases where cable deterioration and changing link conditions can occur.
Nowadays, system designers place heavy improvement demands on tightly coupling the high performance digital processing blocks with their various external analogue requirements. These demands are also compelling distributors to offer well tailored development platforms that can not only help with selling system solutions across the channel but provide standard reference platforms that are fully insured against interoperability and with the confidence that deployment in harsh environments will not pose any issues for customer design-in opportunities.
The SnakeBytes platform is testament to this service since the design and interconnect of the various high performance analogue modules from National using either the PCI or LB interconnects are commonly found in many end applications. Having modules that have schematics and gerber files being readily available to "copy and paste" gives system designers the added comfort in knowing that their sub-system designs will work first time and have been fully debugged and proven to be system robust. With the primary goal in getting the end product out to market within budget and on time this adds significant weight to the role of EBV's reference design methodology.
Conclusion
Promoting a value proposition solely on product features and performance may have worked in the past but the competitive world in which we live nowadays demands more that just this. A collective approach incorporating National, its complementary silicon suppliers and its channel distribution partners are now guiding principles providing a more agile sales force to react quickly with well tailored system solutions for customers that are always faced with the challenges of solving time consuming problems associated with power management schemes alongside the complex analogue signal chain. Essentially, this EBV alliance and reference design platform effectively deploys a distribution channel with a system solution allowing end customers to bring their own end products to market at an accelerated rate.
