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9371 PRBS connection details

Category: Hardware
Product Number: AD9371
We are looking for a way to test the JESD204B link between the Mykonos device and our Xilinx FPGA implementation in both directions. This implementation has four 6Gb/s lanes for the transmit path (deframer)(to the radio antenna), two 6Gb/s lanes for the observation path and two 6Gb/s lanes for the receive path (from the radio antenna).
 
One test approach that we considered was using the PRBS generators in the observation and receive paths, looping them back at the PHY interface of the FPGA's gigabit transceivers, and sending the PRBS data back to the transmit cores of the Mykonos where the PRBS checkers are located.
 
It appears from the documentation that the checker in the deframers can work on a per lane  basis, since MYKONOS_enableDeframerPrbsChecker has a parameter for "lanes".
 
Here are some of our questions:
  1. If the PRBS is sent over the Rx framer or the OBS framer where we are using two lanes, is a PRBS sequence transmitted over each lane (essentially two sequences, one over each lane) or is the pattern shared between the two lanes (one sequence from the core but transmitted using both lanes)?
  1. If the Tx deframer is configured for four lanes, can we configure it as a PRBS checker on two of those lanes (to match the Rx or OBS framer data)? If we can, does it expect a PRBS sequence on each lane or does it expect one sequence shared on both lanes?
I have not found any documentation on this other than the Mykonos Software User's Guide and UG-992. 
If there is a better reference, I would appreciate a pointer to it.
 
  • is the pattern shared between the two lanes (one sequence from the core but transmitted using both lanes)?

    The MYKONOS_enableRxFramerPrbs API is used to  enable the PRBS data that is generated from the  Framer and is output on all the serializer lanes that selected for RX in the lane crossbar settings. So, same PRBS data from the framer goes to two RX lanes. Similarly, MYKONOS_enableObsRxFramerPrbs function can be called to enable the ORx framer to output a PRBS pattern on the serializer lanes. Only the serializer lanes that are connected to the ORx framer are output.

    If the Tx deframer is configured for four lanes, can we configure it as a PRBS checker on two of those lanes (to match the Rx or OBS framer data)? If we can, does it expect a PRBS sequence on each lane or does it expect one sequence shared on both lanes?

    You can select the PRBS checker for each of the four lanes using the API MYKONOS_enableDeframerPrbsChecker.

    From UG:

    When enabled, the JESD204B deframer is disabled and PRBS data is expected on the link instead of framed JESD204B data. The checker is a self synchronizing PRBS checker, as specified in the JESD204B specification. It is capable of checking PRBS7, PRBS15, and PRBS31 sequences.
    The lanes parameter is a bit mask (bit per lane), allowing the checker to be enabled for a particular JESD204B deserializer lane.