Abstract:
A system and apparatus for a compact peripheral component interconnect (CPCI) computer system having exclusive front card access for both active and passive CPCI cards is provided. This system is further comprised of an active backplane with a front and rear side, a plurality of slots, each of these slots comprising of at least one connector and each of these connectors having a column and row arrangement of connector-pins, wherein individual ones of these connector-pins correspond to selected pairs of adjacent slots, and wherein selected adjacent slot pairs are reserved for particular pairs of CPCI cards comprising a single active card and a single passive card.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to Compact Peripheral Component Interconnect (“CPCI”) computer systems. More particularly, the present invention relates to a method and apparatus for providing a CPCI computer system in which front side access is provided for both active and passive CPCI cards.  
           [0003]    2. Description of Related Art  
           [0004]    CPCI is a high performance industrial bus based on the standard PCI electrical specification in rugged 3U or 6U Eurocard packaging. CPCI is intended for application in telecommunications, computer telephony, real-time machine control, industrial automation, real-time data acquisition, instrumentation, military systems or any other application requiring high speed computing, modular and robust packaging design, and long term manufacturer support. Because of its extremely high speed and bandwidth, the CPCI bus is particularly well suited for many high-speed data communication applications such as servers, routers, converters, and switches.  
           [0005]    Compared to standard desktop PCI, CPCI supports twice as many PCI slots (8 versus 4) and offers a packaging scheme that is much better suited for use in industrial applications. Conventional CPCI cards are designed for front loading and removal from a card cage. The cards are firmly held in position by their connector, card guides on both sides, and a faceplate that solidly screws into the card cage. Cards are mounted vertically allowing for natural or forced air convection for cooling. Also, the pin-and-socket connector of the CPCI card is significantly more reliable and has better shock and vibration characteristics than the card edge connector of the standard PCI cards.  
           [0006]    Conventional CPCI defines a backplane environment that is limited to eight slots.  
           [0007]    More specifically, the bus segment of the conventional CPCI system is limited to eight slots, which includes a system slot and peripheral slots. According to conventional standards, the system slot provides clocking, arbitration, configuration, and interrupt processing for up to seven peripheral slots.  
           [0008]    Conventional CPCI systems are further defined by the insertion of front side “active” daughter cards (“front cards”) comprising various signals that “pass-through” relevant interconnect signals and mate with rear side “passive” input/output (I/O) card(s) (“rear transition cards”). As is commonly practiced in the art, rear transition cards are designed to require minimal maintenance relative to front active cards. Consequently, it has also become common practice to physically place the front of these backplanes in a location relatively more accessible than the rear of the backplane (e.g., having the rear side of the backplane facing a wall as opposed to the front side). In several applications (e.g., telephony technology), however, CPCI systems are rapidly increasing in size and complexity. As a result, conventional CPCI architecture has become increasingly problematic whenever rear transition cards require maintenance or replacement in these types of applications.  
           [0009]    Accordingly, there is a need in the art for a CPCI computer system designed to provide improved accessibility to passive transition cards. In particular, it would be advantageous to provide a CPCI computer system in which front side access is provided for both active and passive CPCI cards.  
         SUMMARY OF THE INVENTION  
         [0010]    The present invention relates to a system and apparatus for providing a compact peripheral component interconnect (CPCI) computer system with exclusive front card access for both active and passive CPCI cards. This system is further comprised of an active backplane with a front and rear side, a plurality of slots each comprising of at least one connector and each of these connectors having a column and row arrangement of connector-pins, wherein individual ones of these connector-pins correspond to selected pairs of adjacent slots, and wherein selected adjacent slot pairs are reserved for particular pairs of CPCI cards comprising a single active card and a single passive card, an active card and its corresponding passive card.  
           [0011]    A more complete understanding of the front access only CPCI computer system will be afforded to those skilled in the art, as well as a realization of additional advantages and objects thereof, by a consideration of the following detailed description of the preferred embodiment. Reference will be made to the appended sheets of drawings which will first be described briefly. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]    [0012]FIG. 1 is a perspective view of a conventional CPCI chassis system;  
         [0013]    [0013]FIG. 2 shows the form factor that is defined for the CPCI daughter card;  
         [0014]    [0014]FIG. 3 is a front view of a conventional 3U backplane having eight slots with two connectors each;  
         [0015]    [0015]FIG. 4( a ) shows a front view of a conventional CPCI backplane in the 6U form factor;  
         [0016]    [0016]FIG. 4( b ) shows a back view of a conventional CPCI backplane in the 6U form factor;  
         [0017]    [0017]FIG. 5 shows a side view of the conventional backplane of FIGS.  4 ( a ) and  4 ( b );  
         [0018]    [0018]FIG. 6 is a front view of a customized CPCI backplane according to a preferred embodiment of the invention;  
         [0019]    [0019]FIG. 7 is a schematic of a shunt card according to an alternative embodiment of the invention; and  
         [0020]    [0020]FIG. 8 shows an exemplary implementation of a shunt card according to an alternative embodiment of the invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0021]    In conventional CPCI system architecture, passive transition cards are inserted from the rear where accessibility is limited. Accordingly, there is a need for a CPCI system where these transition cards may be easily accessed whenever maintenance or replacement is required. The present invention addresses this need by providing a CPCI computer system that is adapted to provide front side access for both active and passive CPCI cards. In the detailed description that follows, like element numerals are used to describe like elements shown in one or more of the drawings.  
         [0022]    Referring to FIG. 1, there is shown a perspective view of a conventional CPCI chassis system. The chassis system  100  includes a CPCI circuit board referred to in the conventional CPCI system as a passive backplane  102 . The passive backplane  102  derives its name from the fact that it is located at the back of the chassis  100  and add-on cards (front cards) can only be inserted from the front of the chassis  100 . On the front side of the backplane  102  are slots provided with connectors  104 . In the conventional chassis system  100  that is shown, a 6U daughter card  108  is inserted into one of the slots and mates with a corresponding one of the connectors  104 . For proper insertion of the daughter cards  108  into the slots, card guides  110  are provided. This conventional chassis system  100  provides front removable daughter cards and unobstructed cooling across the entire set of daughter cards  108 .  
         [0023]    Referring to FIG. 2, there is shown the form factor defined for the CPCI daughter card, which is based on the Eurocard industry standard. As shown in FIG. 2, the daughter card  200  has a front plate interface  202  and ejector/injector handles  204 . The front plate interface  202  is consistent with Eurocard packaging and is compliant with IEEE 1101.1 or IEEE 1101.10. The ejector/injector handles should also be compliant with IEEE 1101.1. One ejector/injector handle  204  is used for 3U daughter cards, and two ejector/injector handles  204  are used for 6U daughter cards. The connectors  104   a - 104   e  of the daughter card  200  are numbered starting from the bottom connector  104   a , and both 3U and 6U daughter card sizes are defined, as described below.  
         [0024]    The dimensions of the 3U form factor are approximately 160.00 mm by approximately 100.00 mm, and the dimensions of the 6U form factor are approximately 160.00 mm by approximately 233.35 mm. The 3U form factor includes two 2 mm connectors  104   a - 104   b , which is the minimum number of connectors that are required to accommodate a full 64-bit CPCI bus. Specifically, the  104   a  connectors are reserved to carry the signals required to support the 32-bit PCI bus, hence no other signals may be carried in any of the pins of this connector. Optionally, the  104   a  connectors may have a reserved key area that can be provided with a connector “key”, which is a pluggable plastic piece that comes in different shapes and sizes, so that the add-on card can only mate with an appropriately keyed slot. The  104   b  connectors are defined to facilitate 64-bit transfers or for rear panel I/O in the 3U form factor. The  104   c - 104   e  connectors are available for 6U systems as shown in FIG. 1. The 6U form factor includes the two connectors  104   a - 104   b  of the 3U form factor, and three additional 2 mm connectors  104   c - 104   e . In other words, the 3U form factor includes connectors  104   a - 104   b , and the 6U form factor includes connectors  104   a - 104   e . The three additional connectors  104   c - 104   e  of the 6U form factor can be used for secondary buses (e.g., Signal Computing System Architecture (SCSA) or MultiVendor Integration Protocol (MVIP) telephony buses), bridges to other buses (e.g., Virtual Machine Environment (VME) or Small Computer System Interface (SCSI)), or for user specific applications. Note that the CPCI specification defines the locations for all the connectors  104   a - 104   e , but only the signal-pin assignments for the CPCI bus portion  104   a  and  104   b  are defined. The remaining connectors are the subjects of additional specification efforts, or can be user defined for specific applications, as described above.  
         [0025]    Referring to FIG. 3, there is shown a front view of a conventional 3U backplane having eight slots with two connectors each. A CPCI system is composed of one or more CPCI bus segments, where each bus segment includes up to eight CPCI card slots. Each CPCI bus segment includes one system slot  302 , and up to seven peripheral slots  304   a - 304   g . The CPCI daughter card for the system slot  302  provides arbitration, clock distribution, and reset functions for the CPCI peripheral cards on the bus segment. The peripheral slots  304   a - 304   g  may contain simple cards, intelligent slaves or PCI bus masters.  
         [0026]    The connectors  308   a ,  308   b  have connector-pins  306  that project in a direction perpendicular to the backplane  300 , and are designed to mate with the front side “active” daughter cards (“front cards”), and “pass-through” its relevant interconnect signals to mate with the rear side “passive” input/output (I/O) card(s) (“rear transition cards”). In other words, in the conventional CPCI system, the connector-pins  306  allow the interconnected signals to pass-through from the front cards to the rear transition cards.  
         [0027]    Referring to FIGS.  4 ( a ) and  4 ( b ), there are shown a front and back view of a conventional CPCI backplane in the 6U form factor, respectively. In FIG. 4( a ), four slots  402   a - 402   d  are provided on the front side  400   a  of the backplane  400 . In FIG. 4( b ), four slots  406   a - 406   d  are provided on the back side  400   b  of the backplane  400 . Note that in both FIGS.  4 ( a ) and  4 ( b ) only four slots are provided instead of eight slots as in FIG. 3.  
         [0028]    Further, it is important to note that each of the slots  402   a - 402   d  on the front side  400   a  has five connectors  404   a - 404   e , while each of the slots  406   a - 406   d  on the back side  400   b  has only four connectors  408   b - 408   e . This is because, as in the 3U form factor of the conventional CPCI system, the  404   a  connectors are provided for 32-bit PCI and connector keying. Thus, they do not have I/O connectors to their rear. Accordingly, the front cards that are inserted in the front side slots  402   a - 402   d  only transmit signals to the rear transition cards that are inserted in the back side slots  406   a - 406   d  through front side connectors  404   b - 404   e.    
         [0029]    Referring to FIG. 5, there is shown a side view of the conventional backplane of FIGS.  4 ( a ) and  4 ( b ). As shown in FIG. 5, slot  402   d  on the front side  400   a  and slot  406   d  on the back side  400   b  are arranged to be substantially aligned so as to be back-to-back. Further, slot  402   c  on the front side  400   a  and slot  406   c  on the back side  400   b  are arranged to be substantially aligned, and so on. Accordingly, the front side connectors  404   b - 404   e  are arranged back-to-back with the back side connectors  408   b - 408   e . Note that the front side connector  404   a  does not have a corresponding back side connector.  
         [0030]    It is important to note that the system slot  402   a  is adapted to receive the CPU front card, and the signals from the system slot  402   a  are then transmitted to corresponding connector pins of the peripheral slots  402   b - 402   d . Thus, the conventional CPCI system can have expanded I/O functionality by adding peripheral front cards in the peripheral slots  402   b - 402   d.    
         [0031]    Referring to FIG. 6, there is shown a front view of a CPCI backplane  400  according to a preferred embodiment of the invention. Unlike conventional backplanes, backplane  400  is comprised of an additional set of CPCI card slots  403   a - 403   d  respectively adjacent to CPCI card slots  402   a - 402   d . As illustrated, CPCI card slots  403   a - 403   d  are each further comprised of connectors  405   b - 405   e . In a preferred embodiment, individual connector pins  410   a  within CPCI card slots  402   a - 402   d  are respectively connected to appropriate connector pins  410   c  within adjacent CPCI card slots  403   a - 403   d . In particular, individual connector pins  410   a  corresponding to connectors  404   b - 404   e  are respectively connected to appropriate connector pins  410   c  within connectors  405   b - 405   e.    
         [0032]    Within such embodiment, “active” daughter card(s) (“front cards”) are inserted into CPCI card slots  402   a - 402   d  while “passive” input/output (I/O) card(s) (“rear transition cards”) are inserted into CPCI card slots  403   a - 403   d . Furthermore, it should be appreciated that individual signals corresponding to “active” daughter card(s) inserted into CPCI card slots  402   a - 402   d  “pass-through” hardwire connections implemented within backplane  400  and connect to appropriate signals respectively corresponding to “passive” input/output (I/O) card(s) inserted into adjacent CPCI card slots  403   a - 403   d . As a result, “passive” input/output (I/O) card(s) may be inserted into the front side of backplane  400  with their relevant signals being directly routed to relevant signals corresponding to adjacent “active” daughter card(s).  
         [0033]    It should be appreciated that backplane  400  may be designed to accept 3U and 6U daughter card sizes. As is commonly practiced in the art, the use of 3U card sizes in conventional backplanes requires individual active cards to mate with front side connectors  404   a  and  404   b . Meanwhile, passive cards are required to individually mate with rear connectors  405   b  located in the rear CPCI slot corresponding to the appropriate active card loaded on the front side  400   a . Within this architecture, a 32-bit data bus internally provided by the CPCI system connects directly to all inserted active cards via connectors  404   a . All remaining active card signals are then respectively passed through connectors  404   b  to their corresponding connections in passive cards inserted into appropriate rear connectors  405   b.    
         [0034]    For 6U daughter card sizes, however, it should be appreciated that active cards are individually inserted into front slots  402   a - 402   d  where they mate with connectors  404   a - 404   e . Meanwhile, passive cards are inserted into rear slots  406   a - 406   d  where they mate with connectors  405   c - 405   e . In this architecture, a 64-bit data bus provided by the CPCI system connects directly to all inserted active cards via connectors  404   a  and  404   b . All remaining active card signals are then respectively passed through connectors  404   c - 404   e  to their corresponding connections in passive cards inserted into appropriate rear connectors  405   c - 405   e.    
         [0035]    In an alternative embodiment, active card signals pass through to their corresponding connections in passive cards via printed circuit (PC) boards herein referred to as shunt cards. Within this embodiment, shunt cards are connected to the rear side  400   b  of conventional backplanes  400  in order to “shunt” corresponding adjacent front slots. In particular, this shunt card implementation creates an active/passive front slot pair according to the pair of adjacent slots connected to the shunt card in the rear side  400   b . In FIG. 7, a schematic of a shunt card is shown according to this particular embodiment. As illustrated, these shunt cards  420  are shown to be comprised of female connectors  428   b - 428   e  that are further comprised of a plurality of jacks  410   d . Within this embodiment, appropriate connector pins  410   b  corresponding to adjacent slots are connected by inserting shunt card(s)  420  to the rear side  400   b  of backplane  400 . In particular, these connections are made by mating connector pins  410   b  with jacks  410   d.    
         [0036]    Referring to FIG. 8, an exemplary implementation of a shunt card  420  is provided. In this particular example, shunt card  420  is used in order to “shunt” adjacent slots  406   d  and  406   c  on the rear side  400   b  of backplane  400 . More specifically, shunt card  420  is used in order to respectively connect front card signals in connectors  408   b - 408   e  of slot  406   d  with their corresponding rear card signals in connectors  408   b - 408   e  of slot  406   c . As a result, an active card and its related passive card may both be inserted from the front side  400   a  of backplane  400  using adjacent front side slots  402   d  and  402   c . In this particular example, the operation of CPCI slots  402   a  and  402   b  remains the same as with conventional CPCI backplanes because their signals are not shunted. It should, however, be appreciated that shunt card  420  may be used to shunt any pair of adjacent slots in backplane  400 . It should be further appreciated that similar embodiments may also include multiple shunt cards  420  used in order to shunt multiple sets of adjacent slots as well.  
         [0037]    Similar to the previously described backplane  400 , it should be appreciated that the shunt card  420  may be designed to accept 3U and 6U daughter card sizes. As illustrated in FIG. 8, shunt card  420  may accommodate three female connectors  428   c - 428   e  or four female connectors  428   b - 428   e . Since front side connectors  404   a  and  404   b  are both reserved for communication between 6U active cards and the 64-bit data bus, only three female connectors  428   c - 428   e  are required for 6U daughter card sizes. For 3U card sizes, however, four female connectors  428   b - 428   e  are required because only connector  404   a  is needed to communicate with the 32-bit data bus. Moreover, since front loading 3U active cards are inserted into connectors  404   a  and  404   b  in conventional backplanes  400  and rear loading 3U passive cards are inserted only into connectors  408   b , a female connector  428   b  is required in order to pass the appropriate 3U active card signals to their corresponding connections on the 3U passive card.  
         [0038]    Having thus described a preferred embodiment of a front access only CPCI computer system, it should be apparent to those skilled in the art that certain advantages of the within system have been achieved. It should also be appreciated that various modifications, adaptations, and alternative embodiments thereof may be made within the scope and spirit of the present invention. The invention is further defined by the following claims.