WAKE DETECTION AT CONTROLLER FOR PHYSICAL LAYER OF SINGLE PAIR ETHERNET NETWORK, AND RELATED SYSTEMS, METHODS AND DEVICES
Circuitry for detecting valid signals on a single pair Ethernet bus and related systems are described. Also described are circuits and related systems for wake detection at a physical layer of a network segment, and in some embodiments, wake detection circuitry may include, or use, the signal detection circuitry. In some cases, a low frequency clock generator may be used to clock wake detection circuitry, including during low power modes of operation. In some cases, the low frequency clock generator may be enabled or disabled, selectively, to limit power consumption.
1 . A sleep mode controller of a physical layer of a network segment, the physical layer being an attachment layer between a single pair Ethernet bus and a portion of the network segment, the controller comprising:
an activity detector configured to:
observe signal levels at a bus and at a dedicated input; and
provide an activity detected signal responsive to observed signal levels that exceed specified thresholds, and
a power manager configured to provide a wake-up signal responsive to the activity detected signal.
2 . The sleep mode controller of claim 1 , further comprising an uninterruptible power domain that comprises the activity detector and power manager.
3 . The sleep mode controller of claim 1 , wherein the activity detector comprises first circuitry configured to identify one or more of a valid wake signal and a valid bus activity at the bus.
4 . The sleep mode controller of claim 3 , wherein the first circuitry comprises:
a valid signal detector configured to provide the activity detected signal responsive to one or more of:
a signal duration of the wake signal exceeding a first threshold; and
a signal duration of the bus activity exceeding a second threshold.
5 . The sleep mode controller of claim 4 , wherein the first threshold is a first number of clock cycles and the second threshold is a second number of clock cycles, wherein the second number is different than the first number.
6 . The sleep mode controller of claim 4 , further comprising a bus signal detector configured to:
detect bus activity having a first signal level; and
provide a bus signal responsive to the detecting the bus activity.
7 . The sleep mode controller of claim 6 , wherein the bus signal detector comprises:
a signal detection circuit configured to operably couple to a single pair bus and to detect differential signal amplitudes responsive to specified thresholds.
8 . The sleep mode controller of claim 7 , wherein the signal detection circuit comprises a comparison stage configured to:
compare amplitudes of one or more of positive and negative signals to the specified thresholds; and
provide one or more differential detection signals responsive to the comparison.
9 . The sleep mode controller of claim 8 , wherein the signal detection circuit further comprises a conditioning stage, wherein the conditioning stage is configured to adjust input signals to a specified level for the comparison stage.
10 . The sleep mode controller of claim 9 , wherein the conditioning stage is configured to adjust the input signals to the specified level by performing one or more of:
dividing down a differential voltage of the input signals;
dividing down common mode voltages of the input signals;
amplifying the differential voltage of the input signals; and
amplifying the common mode voltage of the input signals.
11 . The sleep mode controller of claim 6 , further comprising:
a clock generator configured to generate a clock at a first frequency; and
a clock enable configured to selectively enable and disable oscillation of the clock generator responsive to a power mode.
12 . The sleep mode controller of claim 11 , wherein the first frequency is chosen to enable operation of the valid signal detector in an uninterruptable power domain.
13 . The sleep mode controller of claim 1 , wherein the bus is a shared transmission medium is a single twisted pair Ethernet cable.
14 . The sleep mode controller of claim 13 , wherein the bus is a single twisted pair Ethernet cable.
15 . A method, comprising:
generating a clock; and
performing an activity detection process responsive to the clock, the activity detection process comprising:
observing a signal amplitude indicative of a potentially valid signal present at a shared transmission medium;
counting a number of clock cycles of at least part of a signal duration of the potentially valid signal; and
generating a signal indicative of valid activity responsive to detecting that the counted number of clock cycles exceeded a specified threshold.