Data processing: measuring – calibrating – or testing – Measurement system in a specific environment – Mechanical measurement system
Reexamination Certificate
2002-08-02
2003-12-09
Hoff, Marc S. (Department: 2857)
Data processing: measuring, calibrating, or testing
Measurement system in a specific environment
Mechanical measurement system
C702S187000, C710S301000, C710S302000
Reexamination Certificate
active
06662119
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to the field of electronic chassis that house electronic components to be used in, as an example, high-speed telecommunication and networking applications. In particular, the present invention relates to a method and apparatus for monitoring electrical connector degradation in such an electronic chassis by counting the number of insertions experienced by a circuit board to a backplane connector or the like.
BACKGROUND OF THE INVENTION
An electronic chassis that houses electronic components for high-speed telecommunication and networking applications typically includes a plurality of circuit board assemblies. Some of these circuit boards may be referred to as application cards and perform various functions such as digital signal processing. These chassis are often referred to as a high availability platform due to the fact that the chassis are designed for continuous operation. Individual application cards may be inserted and removed for maintenance and other reasons.
The chassis includes a backplane circuit board including various connectors typically fastened to the pair of card guide assemblies. The backplane circuit board forms the back wall of the chassis. When the application cards are inserted into the chassis they are guided into the chassis along a pair of card guide assemblies mounted between the sidewalls of the chassis. One of the card guide assemblies is typically located adjacent the top of the chassis and the other is typically located adjacent the bottom of the chassis. When fully inserted into the chassis, connectors located along the back edge of the application cards are connected to the connectors located on the backplane circuit board. These connectors may be referred to as backplane connectors.
While a variety of electrical backplane connectors are known in the art, all such connectors interconnect circuit boards to a backplane or motherboard to daughterboard. For purposes of this application, backplane connectors will be considered to include a male portion including a plurality of conductive pins or the like, which conduct electrical power or signals. A female portion is typically associated with the application card. The female portion is sized and shaped to receive the male portion while providing proper alignment of the two portions and providing electrical connection with the pins. Other arrangements of the connector portions are contemplated.
As connection densities increase there is an increasing focus on providing a reliable manner of interconnecting a large number of densely organized printed circuit board pads to a connector of minimal size while still providing a high degree of reliability. These types of connectors may suffer failures or reduced reliability resulting from stresses applied to the connectors from insertion and removal of the printed circuit board.
Such electrical connectors often specify useful life expectancy in terms of the number of mates that can be made reliably. Accordingly, there is a demand for a method and apparatus to monitor the degradation of backplane connectors by generating and providing insertion information, such as an insertion count (mates) to a management entity. The present invention satisfies this demand.
SUMMARY OF THE INVENTION
It is an object of the present invention to generate and provide insertion count information with respect to chassis based platforms or like systems where a large number of densely organized printed circuit boards or application cards are employed and connected to the host system by backplane connectors, for example. In such a system, for maintenance and other purposes, the cards may be removed from the backplane connector a number of times during the lifecycle of the card. In order to monitor the effective remaining useful life of an individual connector on the card, it is an object of the invention to generate, store and report data related to the number of times that a particular card has been removed and inserted into the slot of the backplane connector.
Briefly, the invention relies on an insertion monitor circuit to indicate a connector mate. During the power up sequence of an application card, the insertion monitor makes use of physically staggered terminals or pins on an application card being connected to a backplane connector in a specified mating sequence to identify an insertion event. The staggered arrangement of pins guarantees the mating sequence in a predetermined order.
With respect to the insertion monitor circuit, in one embodiment of the invention, hardware resource bus (HRB) power pin(s) make electrical connection to a backplane connector prior to a single sense line. It may be assumed in this embodiment that a digital ground is already connected. In another embodiment, the HRB pin makes electrical connection to a backplane connector prior to two sense lines. In this embodiment, both sense lines must be grounded before the sequence is completed. This sequence first provides power to the insertion monitor circuit and provides voltage to sense resistor pull-ups of the card. Subsequent to contact of the HRB pins, one or more sense pin is mated to the backplane connector. As a result, the sense pins are grounded on the backplane. This causes the circuit to transition from a high voltage to a low voltage. This transition from a high state to a low state is detected by the circuit and used to indicate an insertion.
Either a single sense line may be used or a combination of two or more spaced sense lines. In the event that two independent sense lines are used, the lines are physically spaced on opposite ends of the card so as to ensure complete seating of the card with the connector before the insertion detection occurs. In this case, both sense lines are required to become grounded before the circuit completes the transition and an insertion count is subsequently incremented. Further, a debounce circuit, as known in the art, may be used to reduce errors during mating of the card. The debounce circuit is used to produce a single transition of the state of the card when inserting the card. Without a debounce circuit, it is possible to see multiple transitions on the insertion detection circuit. Debouncing is common when interfacing electronics to mechanical systems. In one example of a debounce circuit, a timer is used, which requires that both sense lines are grounded for a predetermined length of time before subsequent next steps occur in the process of indicating an insertion.
In the event that the insertion detection device detects a transition from a high state to a low state, a state device reads the contents of a non-volatile storage device (for example, EPROM, EEPROM and FLASH) to obtain the current insertion count value, updates the insertion count value by incrementally adding to the count value and writes the updated incremented count value to the non-volatile storage device.
It will be understood that the insertion detection circuit may include a hardware device or a combination of hardware and software. One example of a hardware device around which the insertion detection circuit may be implemented is a programmable logic device (PLD).
The advantage of using staggered terminals or pins is that the resulting sequence allows for differentiation between card insertion, and chassis power up. While it is assumed that a high-availability chassis is rarely powered off, the act of powering a chassis on and off will not be counted as an insertion event if the staggered pins are used to sense insertion. This is because after insertion, the sense lines are already mated to the connector when the chassis is powered off. When the chassis is subsequently powered up, the backplane holds the insertion sense lines low, and a transition from a high state is not seen on the sense lines or detected by the insertion detection circuit. Accordingly, no change in status is noted and an insertion count is not incremented.
In one embodiment of the invention, an insertion detection/state device/EEPROM can all be powered off ha
3Com Corporation
Baniak Pine & Gannon
Hoff Marc S.
Morris Andrew
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