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Independent power cycler Disclosure Number: IPCOM000028205D
Original Publication Date: 2004-May-03
Included in the Prior Art Database: 2004-May-03
Document File: 2 page(s) / 64K

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Independent power cycler

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Independent power cycler

    Using a circuit to leverage the PME# (Power Management Event) for PCI and an optional timing circuit one can do OS cold power cycling and OS independent (could use a boot disk) power cycling. All other solutions require the purchase of external hardware (some type of pass-through device with generated device drivers for every OS).

    Hardware Description The PME# signal is used by PCI device (normally network) to turn the computer back on. By using this property, a simple computer independent PCI/PCI-X card can power cycle the system. Simply put, once the computer turns off somebody has to turn the computer back on. The card sensing the loss of power then knows it will have to turn on the computer. It asserts the PME# signal as specified by the PCI specifications: "PME# (pin A19) is an active-low shared, open-drain signal that a sleeping PCI function may use to request that the OS change its PM state in response to an event that has been detected. Once restored to full-power and capability, the function, under the direction of its device driver, can take the series of actions necessary to service the event "(PCI 2.2 Specification).

    The process flow for the power cycle is this: The user installs the card, turns on the computer and sets the software to power cycle. Once the computer is completely operational, the software then tells the computer to shut down. Once power is removed from Vcc on the PCI bus, the card will know to power the computer back on. As a side note, this can be done with or with out delay. The card takes the PME# signal to a low state. This tells the computer to turn on. Once Vcc power is available and steady, the card will bring PME# back high. There is available power through 3.3Vaux to keep the card power management function active, so there is no need for external power. If the software is still configured to power cycle the process starts over again. The solution can be implemented from a simple logic circuit or as a dedicated PCI chip design using an ASIC. As a dedicated card, the user define configuration space can used to set card operation values through the PCI bus. The timers are completely...