Xilinx Virtex-5 RocketIO GTP User Manual page 80

Chapter 5: Tile Features
After a TX Buffer Error
When the TX buffer overflows or underflows, it must be reset using TXRESET to ensure
correct behavior.
After an RX Buffer Error
After an RX buffer overflow or underflow, the RX buffer must be reset using the
RXBUFRESET port to ensure correct behavior.
Before Channel Bonding
For successful channel bonding, the RX buffers of all the bonded transceivers must be
written using the same recovered frequency, and read using the same RXUSRCLK
frequency.
To provide the same RXUSRCLK frequency to all bonded transceivers, use a low skew
clock buffer (for example, a BUFG) to drive all the RXUSRCLK ports from the same clock
source. Bonding should not be attempted until the clock source is stable.
To provide the same recovered clock to all bonded transceivers:
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The required reset for channel bonding is as follows:
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•
•
•
See
CDR lock.
PRBS Error
To clear the RXPRBSERR signal after the PRBS error threshold is exceeded, assert
PRBSERRRESET.
Oversampler Error
If RXOVERSAMPLEERR goes High to indicate an overflow or underflow in the
Oversampling block, assert RXRESET to clear it.
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All of the TX data sources must be locked to the same reference clock
All of the bonded transceivers must have CDR lock to the incoming data
Assert RXELECIDLERESET to reset the CDR for all bonded transceivers
Wait for CDR lock and bit alignment on all bonded transceivers
Apply RXBUFRESET to all bonded transceivers
Attempt channel bonding
"RX Clock Data Recovery (CDR)" in Chapter 7
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for recommended methods of detecting
Virtex-5 RocketIO GTP Transceiver User Guide
UG196 (v1.3) May 25, 2007
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