Usage Models for Advanced Mezzanine Card (Advancedmc)
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SPECIFICATION CORNER By John Beaton Usage models for Advanced and Mark Summers Mezzanine Card (AdvancedMC) CompactPCI The PCI Industrial Computer Manufacturers Group (PICMG) AMC.x, more commonly known as Advanced Mezzanine Card (AdvancedMC), is the next-generation mezzanine standard designed to enhance modularity and ser- ial connectivity for AdvancedTCA and other carrier-grade communications platforms. The use of mezzanine cards enables manufacturers to implement a variety of embedded processors, Digital Signal Processors (DSPs), network processors, and other components. Each AdvancedTCA board can support up to four AdvancedMC mezzanine cards, which provides new ways for manufac- turers to meet their reliability, availabil- ity, serviceability, and cost requirements. The good news is that the list of potential usage models for AdvancedMC mezza- nines is practically unlimited. It includes I/O cards, processor cards, storage mod- Figure 1 ules, packet processing modules, fabric conversion cards, security modules, and more. In this article, the second in a Shares of Dollar continuing series on AdvancedMC, Mark Volume Shipments and John look at how PICMG AMC.x by Vertical Market, subsidiary specifications now under 2002-2004 development will support traditional usage models, some not-so-obvious uses, and areas where AdvancedMC may not be the best choice. Traditional usage models The usage models for AdvancedMC gen- erally extend current mezzanine usage. Figures 1 and 2 depict how mezzanine cards are used in various vertical markets, as reported by Venture Development Corp. The top three applications, in terms of dollar volume, include communications equipment, military-aerospace, and indus- trial applications, which altogether repre- sent over 90 percent of total mezzanine revenue. Figure 2 breaks out the quantity of mezzanine cards shipped in 2003 by their function. I/O and processor cards makeup almost two-thirds of the total number of units shipped. Adding-in com- munications-oriented mezzanines raises this total to 83 percent. Existing mezzanine specifications origi- nated with a sharp focus on I/O, and have Figure 2 Reprinted from CompactPCI Systems / November 2003 ©Copyright 2003 evolved organically to add various proces- ground pins to absorb loop current, faster were typically unable to handle anything sor and telecom capabilities. These speci- PCI buses are only point-to-point. Sup- but discrete components on the secondary fications include the following: porting multiple devices on a mezzanine side (Side-2). CMC allows only 1.9mm, card requires a bridge chip that adds com- while AdvancedMC provides a minimum ■ PMC: PCI Mezzanine Card, plexity, dissipates more power, and uses of 2.6mm that provides enough room for IEEE1386.1. valuable mezzanine real estate. Moving to Ball-Grid-Array (BGA) packages. ■ PrPMC: Processor PCI Mezzanine a high-speed serial interconnect supports Card, VITA-32. higher bandwidth devices, or allows mul- As shown in Figure 3, an analysis of 50 ■ PTMC: PICMG 2.15 with tiple devices to be supported without an components most often used on mezzanine 10/100/1000 Ethernet. onboard bridge chip. Serial interconnects cards shows that a sweet spot of a 2.6mm also provide greater pin-efficiency. High- minimum backside component height All of these specifications are based on speed serial interfaces that provide 1 Gbit/ allows for the maximum use of real estate. the CMC spec, or IEEE 1386.0, the base sec or more of usable bandwidth per pin mechanical spec. Other mezzanine form minimize connector cost and size, and The primary component side should also factors are designed to fill market niches, also minimize the mezzanine area devoted be deep enough to support both active and include Industry Pack, PC•MIP, and to the external connection. components with heat sinks and storage M-Modules. devices, and needs a deep mechanical en- Real estate velope that extends all the way from the Key determinants Mezzanine real-estate specs should support front panel back to the connector. Com- The five key factors that determine valid components on both sides and allow room mon Mezzanine Card (CMC) provides usage models for AdvancedMC mezza- on the primary component side for suffi- 10mm at front, but only 4.5mm at the nines are the same as the key design para- cient airflow. Previous mezzanine cards back. By comparison, AdvancedMC pro- meters for the specification: ■ Bandwidth ■ Real estate ■ Thermal envelope ■ Interconnects ■ Manageability AdvancedMC supports evolving require- ments in each of these areas. The advan- tages are summarized in Table 1. Bandwidth The parallel buses of existing mezzanine cards use faster and wider Peripheral Component Interconnect (PCI) buses to provide Gbit/sec-class peak bandwidths (with much lower sustained bandwidths), but at the cost of pin count and connectiv- ity. Even with a large number of extra Figure 3 Features PMC AdvancedMC Form factor Single and Double-Wide Single and Double-Wide Full Height Regular or Double Stacked Half Height Real estate 74 mm x 149 mm 72 mm x ~190* mm (175 usable) 1.9 mm max. backside height 2.6 mm min. backside height Connectors Unshielded P1386 Shielded Differential Pairs (20 duplex ports) Interconnects PCI 32/33; 33/64; 66/32; 66/64 “Agnostic” Ethernet 1 Gigabit Ethernet, Fibre Channel, PCI-Express, IBX, XAUI, 10 Gigabit Ethernet Bandwidth PCI: 1-4 Gbits/sec 1 to > Nx10 Gbits/sec Ethernet: 1 Gbits/sec Native manageability No Yes IPMI (Intelligent Platform Management Interface) Hot swap No Yes Power for 1X wide 7.5/12* Watts ~35** Watts/Bay * VITA-32 PrPMC wattage allowance **Dimensions or values that are still in debate by the PICMG AMC.0 Subcommittee Table 1 Reprinted from CompactPCI Systems / November 2003 ©Copyright 2003 SPECIFICATION CORNER vides 13mm at the front, and 11mm at the AdvancedMC specification includes the include a small-scale switch. back that provides enough room for high Intelligent Platform Management Interface components and high air flow, and even (IPMI), while PMC and PrPMC do not. With the obvious uses for an Advanced- enough for a 2.5-inch/70mm hard disk MC mezzanine card accounted for, it is drive at the front of the card. The Ad- AdvancedMC usage models time to look at some less-obvious uses. vancedMC is also longer than previous I/O devices These more obscure uses will take advan- mezzanines, or 175mm deep. The peripherals connecting to a general- tage of the 40 differential pairs available purpose processor would presumably use on AdvancedMC. Thermal envelope a direct descendant of PCI, such as PCI The thermal envelope, both in terms of Express. The same is true for peripheral Fabric cards power delivery and power dissipation, is chips used to connect to general-purpose With 20 lanes of HSS I/O, an Advanced- another key spec. The PMC mezzanine is processors. Network-oriented I/O de- MC mezzanine could function as a small- rated at only 7.5W, and the PrPMC mezza- vices that are part of the primary or fast scale fabric card, since the fabric itself nine at 12W. Since higher bandwidth trans- data path, such as a framer, would pre- could easily be implemented with a single lates directly into higher power, these ther- sumably use SPI or a similar interface switch chip. Putting two mezzanines on a mal envelopes are clearly too small. A that allows direct connection to a net- baseboard creates a redundant fabric. single-wide AMC mezzanine has a 30W work processor. thermal envelope, and for added flexibility RTM adapter cards the connector can deliver 60W to the card. General-purpose processors The rear transition module (RTM) on This allows for a double line card to be This covers any number of sub-categories AdvancedTCA is designed to allow per- powered from a single connector, and also including control processors, network ser- sonalized customization for each blade, provides an element of future-proofing on vice and application processors, adjunct since the user-defined signals do not need the assumption that more efficient thermal processors, server micro-blades, and chas- to adhere to strict standards. Another mez- management technologies will be devel- sis/shelf management controllers. This zanine usage model of interest is the RTM oped. In an effort to reduce cost and time- category covers an extremely broad range Adapter Mezzanine Card, which allows to-market, the AdvancedMC Side-1 height of performance, bandwidth, and power an even greater level of mission-critical is sufficient to allow designers to reuse dissipation characteristics. customization. existing CompactPCI mezzanine solutions. Network processors Power converters Interconnects High-end network processors with through- The power to the AdvancedTCA carrier AdvancedMC assumes a High Speed put of up to 10 Gbits/sec typically require card is -48 VDC. Unfortunately, most Serial (HSS) interface to the baseboard, far more area and power than a mezzanine electronic components require a substan- for greater bandwidth and pin efficiency. could be expected to provide. However, tial amount of power conversion from this The AdvancedMC connector could be high-volume opportunities at data rates of base voltage. On AdvancedTCA carrier used for other types of interfaces, but OC-12 and below, coupled with the trend cards where real estate is limited, the only if pin count is not an issue. The towards functional integration in network AdvancedMC card could function as AdvancedMC committee is currently processors, makes AdvancedMC an inter- power conversion mezzanine card. considering PCI Express, Advanced esting possibility. Switching, GigE, RapidIO, InfiniBand, Memory cards Serial ATA, Serial Attached SCSI, and Coprocessors Communications systems use a wide vari- Fibre Channel. The committee is also con- This category could include a wide ety of memory types. Possibilities include sidering system packet interface 4.2 (SPI variety of processors, including crypto, a flash array for nonvolatile storage of 4.2), the lone exception to the HSS rule.