Problems with a High Bit Error Rate
R
RocketIO Transceiver Specific
When using a RocketIO transceiver, perform these additional checks:
•Ensure that the polarities of the TXN/TXP and RXN/RXP lines are not reversed. If they are, this can be easily fixed by using the TXPOLARITY and RXPOLARITY ports of the RocketIO.
•For
•Check that the RocketIO is not being held in reset by monitoring the mgt_tx_reset and mgt_rx_reset signals between the core and the RocketIO. If these are asserted then:
♦In
♦In
•Monitor the RXBUFSTATUS[1] signal
Problems with a High Bit Error Rate
Symptoms
The severity of a
•Failure to complete
•Failure to obtain a link when
•High proportion of lost packets when passed between two connected devices that are capable of obtaining a link through
Note: All bit errors detected by the
Debugging
•Compare the problem across several devices or PCBs to ensure that the problem is not a
•Try using an alternative link partner or test equipment and then compare results.
•Try putting the core into loopback (both by placing the core into internal loopback, and by looping back the optical cable) and compare the behavior. The core should always be capable of
•Try swapping the optical module on a misperforming device and repeat the tests.
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