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Virtex-5 RocketIO GTP Transceiver User Guide
UG196 (v1.3) May 25, 2007
Appendix B:
OOB/Beacon Signaling
R
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.
Figure B-2:
SATA COM Sequences
320 ns
106.7 ns
106.7 ns
106.7 ns
COM
W
AKE
COMRESET
COMI
N
IT
UG196_B_02_092606