Beacon Signaling In Pci Express - Xilinx Virtex-5 RocketIO GTP User Manual

Appendix B: OOB/Beacon Signaling
In addition to the analog circuitry required to encode and detect the OOB signal state, the
GTP transceiver includes state machines to format and decode bursts of OOB/beacon
signals for SATA (COMRESET, COMWAKE, and COMINIT).

Beacon Signaling in PCI Express

PCI Express uses sequences called beacons to wake endpoints from powerdown states. A
beacon is the transmission of K28.5 (COM) characters. A beacon sequence can have a
frequency anywhere from 30 kHz to 500 MHz.
The PCI Express specification describes the beacon mechanism as an inband wakeup
indication, and defines the use of a discrete wake signal (WAKE#) as an out-of-band
mechanism.
GTP transceiver support for PCI Express beacons uses interface signals defined in the PHY
Interface for the PCI Express (PIPE) Specification. Control logic in the FPGA manages the
format of the beacon sequence.
268
106.7 ns
COMWAKE
106.7 ns
106.7 ns
COMRESET
COMINIT
320 ns
Figure B-2: SATA COM Sequences
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Virtex-5 RocketIO GTP Transceiver User Guide
UG196 (v1.3) May 25, 2007
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