Virtex-5 RocketIO GTP Transceiver User Guide
133
UG196 (v1.3) May 25, 2007
RX OOB/Beacon Signaling
R
SATA OOB Detection
Each GTP transceiver includes a SATA OOB detector to decode SATA COM sequences.
When RX_STATUS_FMT is set to
SATA
, the pins of the RXSTATUS port are used to indicate
the arrival of COM sequences.
shows the SATA OOB detector. It divides CLKIN
down to create a squelch clock that runs at approximately 25 MHz. This clock is used to
sample the output of the block that detects OOB signals to look for transitions between
regular data and OOB signals. Both edges of the squelch clock are used. The squelch
detector FSM uses the transitions to calculate the length of each burst and each idle. It uses
this information to drive the RXSTATUS port, indicating which COM sequences have been
found.
Before the SATA OOB detector can work, it must be configured to use the reference clock
provided (CLKIN). The OOB_CLK_DIVIDER attribute must be set to produce a squelch
clock between 25 MHz and 37.5 MHz, and as close to 25 MHz as possible. In addition, the
MIN and MAX times for bursts and idles must be set based on the squelch clock rate. The
formula to set the squelch clock is shown below:
Equation 7-1
All the minimum values are defined with a minimum time below which the signal must be
rejected, and a minimum time above which the signal always meets the minimum time
requirement. After calculating each of these in terms of squelch clock cycles, the
appropriate MIN parameter is set to an integer value between these two numbers.
Similarly, for all maximum values, there is a maximum time above which the signal must
be rejected, and a maximum time below which the signal always meets the maximum time
requirement. After calculating these in terms of squelch clock, the appropriate MAX
parameter is set to an integer value between these two numbers.
Figure 7-3:
SATA OOB Detector Block Diagram
S
qu
elch
FSM
S
qu
elch
Di
v
ider
S
qu
elch
Clock
CLKI
N
RXP
RXELECIDLE
COMI
N
IT
COM
W
AKE
RX
N
OOB_CLK_DI
V
IDER
SATA_MI
N
_BURST
SATA_MAX_BURST
SATA_MI
N
_I
N
IT
SATA_MAX_I
N
IT
SATA_MI
N
_
W
AKE
SATA_MAX_
W
AKE
OOBDETECT_THRESHOLD
D Q
D Q
Peak
Detector
amp
UG196_c7_03_013007
Parameter in squelch cycles
Parameter in ns
1000
-----------------------------------------
⎝
⎠
⎛
⎞
squelch clock frequency in MHz
2
×
×
=