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TLK1501: Bidirectional Communication Issue

Cijo Thomas
Prodigy 10 points
Part Number: TLK1501
Other Parts Discussed in Thread: LMK6C

Tool/software:

Hi,
I designed a board using the TLK1501 and an SFP module for communication between two identical boards over fiber. However, I am facing an issue with bidirectional communication.

  • When Board A transmits, Board B receives successfully. But if Board B transmits simultaneously, Board A does not receive the proper data (Junk data coming).
  • If I power cycle Board A, Board A starts receiving data from Board B, but at the same time, communication from A to B is lost.

Has anyone encountered a similar issue or have any suggestions on what could be causing this problem?

Board working @ 50Mhz


  • 0
    TI__Mastermind 27610 points

    Hi,

    I believe the issue is that GTX_CLK is supplied directly from an oscillator. TXD[15:0] inputs are sampled on the rising edge of GTX_CLK, therefore GTX_CLK should be synchronous with data inputs.

    Best,

    Lucas

  • 0 in reply to Lucas Wolter
    Prodigy 10 points

    Hi Lucas,

    Thanks for your input. That makes sense.

    Do you have any suggestions on how we can synchronize GTX_CLK with the data inputs? In our setup, we have 10 serial data streams coming from different sensors, each operating at different timings and baud rates on Board A, which need to be transferred to Board B. Given this variability, what would be the best approach to align the GTX_CLK with the inputs to ensure proper sampling?

    Additionally, I suspect the oscillator might be contributing to the issue. Could the choice of oscillator affect the synchronization? Do you have any recommendations for a reliable oscillator for GTX_CLK or specific requirements we should consider while selecting one?

    Looking forward to your thoughts.

  • 0 in reply to Cijo Thomas
    TI__Mastermind 27610 points

    Hi Cijo,

    Do each of the sensors require reference clock inputs? Could it be possible to use a single oscillator as a reference clock for all sensors and the TLK1501? I believe this will be the best method to synchronize data inputs and GTX_CLK.

    GTX_CLK needs to meet the following specifications.

    I believe LMK6C can be a good choice.

    Best,

    Lucas

  • 0 in reply to Lucas Wolter
    Prodigy 10 points

    The data is asynchronous and is sent by external devices. The issue we are facing is that only one of the TLK1501 receiver functions correctly at a time. If we power cycle one TLK1501, it starts receiving properly, but the other TLK1501 goes out of sync, resulting in junk data.

    How can we ensure that both TLK1501 modules receive and transmit data simultaneously without synchronization issues? 

  • 0 in reply to Cijo Thomas
    TI__Mastermind 27610 points

    Hi Cijo,

    You mentioned that Board A includes 10 serial streams coming from different sensors, each operating at different timings and baud rates. Are these all connected to the TXD inputs of a single TLK1501?

    TLK1501 is not capable of serializing and transmitting asynchronous inputs. TXD inputs are sampled on the rising edge of GTX_CLK, so it's not possible to sample asynchronous data streams which don't even operate at the same rate.

    Best,

    Lucas