System for periodically transmitting signal to/from sleeping node identifying its existence to a network and awakening the sleeping node responding to received instruction

Patent 5404544 Issued on April 4, 1995. Estimated Expiration Date:

June 5, 2012. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.

Abstract Claims Description Full Text

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Inventor

Crayford, Ian

Assignee

Advanced Micro Devices, Inc.

Application

No. 894016 filed on 06/05/1992

US Classes:

713/310, By external command340/5.74, Access to electrical information713/323Active/idle mode processing

Examiners

Primary: Lee, Thomas C.

Attorney, Agent or Firm

Caserza; Steven F.

Foreign Patent References

0343630 EP. 05/12/1989
9203004 WO. 02/12/1992

International Classes

G06F 013/38
G06F 001/30

Abstract

One of the fundamental benefits of the 10BASE-T physical interface for 802.3/Ethernet is that the health of the communications link can be permanently monitored. When in the "link good" condition, the 10BASE-T transceiver is required to output a link status (LNKST) signal to this effect. Media Access Controller (MAC) 30, with an embedded 10BASE-T transceiver (37), uses the LNKST signal to provide power management to the MAC (30). By using the programmable AWAKE bit, the receive section of the 10BASE-T transceiver (37) can remain powered, even if the SLEEP input to the MAC (30) is activated. This allows the transceiver (37) to detect a link beat pulse (60) or receive packet activity. If either receive condition is encountered, the internal transceiver (37) will activate the LNKST output from the MAC (30). The system hardware and/or software can use the LNKST output to take appropriate action. For instance, if the LNKST output is active (low), then the computer is connected to an active network, and it is likely that the operating system will allow the MAC (30) to remain powered. However, if the LNKST becomes inactive (high) then the system can assume that the link is inactive, and the MAC can be powered down to save power. If at a later time the link is re-established, the MAC (30) can be powered back up to take advantage of the communications channel. In this way, the power consumption of the Ethernet connection can be managed by the operating software/hardware.