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Original question:

AFE7950: JESD 204B LMFSHd

AFE7950: Regarding the mapping between AFE7950 JESD lane and DAC

Yake Li
Prodigy 120 points
Part Number: AFE7950

Tool/software:

Hi TI Team，

            I have already connected the JESD204B link on ZCU102 and AFE7950EVM. The script I am using is: TI_IP_10Gbps_8Lane_ConfigLmk.py . 

           The DAC sampling rate of this script is 491.52MSPS.  This does not meet our customer's needs, they require a bandwidth of 1.5GHz. 

           Due to the speed limitation of GTH，We cannot use JESD 204C to expand bandwidth. But we only need one TXA interface,  I want to know if AFE7950 can turn off TXB, C, and D, and then use all 8 JESD lanes （or 4 lanes）for TXA?   If possible, how should I modify the script file?

  • 0
    TI__Genius 17831 points

    Hi Yake,

    The max instantaneous bandwidth supported by the AFE is 1.2GHz, interface rate of 1.5GSPS. 

    The AFE supports splitting the the data of one channel to a max of 4 lanes, LMFS of 42220. Please use example script 'S7_OnboardClk_42220.py' as a starting point as this is already configured for that LMFS.

    Regards,

    David Chaparro 

  • 0 in reply to David Chaparro
    Prodigy 120 points

    Hi David，

          If I use LMFS as 42220, how should I modify the corresponding lane data in the FPGA code?  What is frame format？ 

    Regards,

    Yake

  • 0 in reply to David Chaparro
    Prodigy 120 points

    Hi David Chaparro，

      Thanks for your reply. 

      I am currently using this script: S7_OnboardClk_42220.py

      The duc in the script is 12, and when I change it to 8, it runs normally. But if I change it to 9 or 10, there will be an error when running it. Are there any restrictions on the value of duc?

    Regards,

    Yake

  • 0 in reply to Yake Li
    TI__Genius 17831 points

    Hi Yake,

    The frame format for this mode is given below. The supported interpolation factors are given in table 8-6 of the datasheet. At 12GHz Fs, interpolation factors of 9 and 10 are not supported. Is there a certain data rate that you are trying to achieve? 

    Regards,

    David Chaparro

  • 0 in reply to David Chaparro
    Prodigy 120 points

    Hi David Chaparro，

      Thanks for your reply. 

       When the DUC is 8, the lane rate of the GTH is 14.7456Gbps,  so I want to reduce the speed by changing the DUC to 9 or 10. This is just my idea.，If it cannot be achieved, it's okay.

      I have another question： In the script, we only enabled  txB and txD，  Then set sysParams. txDataMux=[2,3,0,1,6,7,4,5]，  How do the two sides correspond?  From the GUI, JESD RX can only see TX2IB0, TX2QB0, TX1IB0, TX1QB0.  

             From the GUI,  Because RXA and RXC are enabled, the lane mux data corresponding to JESD is RX1& RX3

    How should I understand the correspondence between JESD RX/TX lanes and TxABCD/RxABCD channels?

    Regards,

    Yake