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DP83TC811R-Q1: Seeking a support to use TI PHY in Passive mode

Vishal Dhanani1
Prodigy 110 points
Part Number: DP83TC811R-Q1
Other Parts Discussed in Thread: DP83TC811, DP83TC811SEVM, DP83TC811EVM
Hi,
We are in architecture phase for test and measurement device for automotive Ethernet protocol, which is targeted to generate trigger for configured automotive ethernet frames being captured/probed.
We have done some initial testing on the EVMs and we are able to get on conclusion that PHY is able to provide output when it is interfaced with logical link connectivity mode in both master and slave mode.
We have a different requirement that PHY should just operate in passive mode where it will descramble /decode received data of single direction (PAM -3) traffic being sent by Master or Slave, in this scenario TI's phy should not initiate any traffic, but will be used as passive device to decode received PAM 3 data on TRD_M/_P line and generate digital data on RGMII interface.
Is there any way to fulfill this requirement?
Regards,
Vishal
  • 0
    TI__Mastermind 23675 points

    Hi Vishal,

    This is outside of what an IEEE802.3bw PHY should do. 

    Will the PHY be essentially snooping a line with two other PHYs actively communicating?

    If so, the PHY will have no way of knowing if the information is from the master or the slave PHY.

    Please send a diagram on what the application is.

  • 0 in reply to Ross Pimentel
    Prodigy 110 points

    Hi Ross,

    Please see my response as below:

    This is outside of what an IEEE802.3bw PHY should do. 

    Vishal] Yes you are right, we are aware of that.

    Will the PHY be essentially snooping a line with two other PHYs actively communicating?

    Vishal] Yes, TI PHY will be snooping a line with two other phy/automotive ethernet end points (master and salve) already communicating with each other.

    If so, the PHY will have no way of knowing if the information is from the master or the slave PHY.

    Vishal] We have designed hardware circuit to separate single direction traffic signal from line with two other PHYs actively communicating. i.e. output of this circuit is two differential pair, One is PAM 3 signal being transmitted from Master to Slave and Other is PAM 3 signal from Slave to Master. 

    We just wanted to figure out whether TI PHY has any special configuration/settings just to descramble\decode signal received from (known source) Master when it is configured in Slave mode and vice versa.

    Regards,

    Vishal

  • 0 in reply to Vishal Dhanani1
    TI__Mastermind 23675 points

    I cannot confirm if this will work with the DP83TC811.

    You can experiment in your lab by using a DP83TC811EVM or DP83TC811SEVM.

    It can potentially work, but you will need to have a directional coupler going to the 811 to prevent it from transmitting back to the partner.