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TLK1501 K28.5 , D5.6

roland stiglmayr
Prodigy 20 points
Other Parts Discussed in Thread: TLK1501

Hello,

I use the TLK1501 as a serializer/ transmitter. I want toggle RD of the Idle word. TLK always sends K28.5, D16.2 in a sequence. As a result the starting disparity for K28.5 is always -1 and K28.5 RD never toggles.

If, as written in data sheet, K28.5, D5.6 would be sent, RD would toggle as wished.

How can I force D5.6?

Thanks, Roland

  • 0
    TI__Mastermind 20820 points

    Hi Roland,

    The RX_DV pin is an output only and needs to be toggle through the TX_EN and TX_ER pins. Table 1 in the data sheet for the TLK1501 explains the operation of the device in the different states of the TX_EN and TX_ER pins. If you want to force the device to send K28.5, D5.6 or K28.5, D16.2 then the TX_EN an TX_ER pins need to be tied low. Make sure that the PRBS generator is disabled as well so that the device is not sending out PRBS data.

    Regards,

    Mike

  • 0 in reply to Michael Peffers
    Prodigy 20 points

    Hi Mike,

    what you advise is exactly what I do.

    After PON, TX_EN and TX_ER are low. PRBSEN is high. LCKREFN is low to force transmit only.
    The result is stable bit pattern for K28.5 with b0011111010 followed by b1001000101 for D16.2 DOUTTXP.

    These data stream is sent continuously without changing to the other representation of
    K28.5 with the pattern b1100000101. This also correct, because the RD(running disparity)  is -1 when starting encoding of K28.5.

    If the sequence K28.5 D5.6 would be sent instead, RD would toggle and the alternative representation for K28.5 would be used. Table 1 of data sheet specifies while TX_EN and TX_ER is low "K28.5, D5.6 or K28.5, D16.2".
    What is meant with or?
    I never found D5.6 after the comma.  Even when I placed random data in the string by a short enabling of PRBS.

    Regards,

    Roland