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DP83867CR: DP83867 use for Multi-Port

Girish Babu
Prodigy 20 points
Part Number: DP83867CR


Hi,

We are using iMX8 SMARC module, it has Texas InstrumentsTm DP83867 Ethernet Controller the module.

And we interfaced the DP83867 module with integrated magnetic RJ45 connector.

So, we are able to link and achive the 1000mbps speed.

But we are planning to use the same ethernet port to generate the IEEE-specified five level pulse amplitude modulated (PAM) signals.

Generally, voltage mode line driver uses series resistors to generate the PAM signal at the magnetic. 

The DP83867 datasheet is saying that it has integrated termination resistors, may i know what the value of termination resistors is used??

If want to generated PAM signal, do we need to add any value of external series termination resistors??

Thanks & Regards,

Girish

  • 0
    TI__Mastermind 19621 points

    Hi Girish

    First, force PHY to 1000 Mbps (Auto-Negotiation needs to be Disabled).

    This can be done by Writing to Register 0x0000, disabling auto-neg and choosing speed (bit 6 & 13)

    Signal would need to be measured across a 100 Ohm Termination Resistor connecting the positive and negative channels of one of the twisted pairs.

    Regards,

    Alvaro

  • 0 in reply to Alvaro (Al-vuh-roe) Reyes
    Prodigy 20 points

    Hi Alvaro,

    Thanks for the replay, 

    I can do the Auto-Negotiation to be Disabled but my host will support only 10BASE-T only. I mentioned below specifications of HOST and Device in detailed.

    M-Port device Specifications are: HOST (BCC)

    1. M-Port Host shall provide an IEEE 802.3 10BASE-T Ethernet facility.

    2. M-Port Host Ethernet pinout shall use “hub” pinouts (pin 1/2 RX+/- & pin 3/6 TX+/-) and thereby comply with the IEEE 1073.3.2 Alternate Lower Layer.

    M-Port Devices that Implement Ethernet shall conform to the IEEE 802.3 10BASE-T Ethernet Standard. If Ethernet is not implemented, the Device-side should have the + / - Receive (Rx) Lines (pins 3 & 6), differentially terminated with 100 Ohms or less to comply with the IEEE 1073.3.2 Alternate Lower Layer Specification.

    Connectivity device Specifications are: Device (DCC)

    Sl. No

    Difference

    M-Port Device (Monitor)

    Atlanta Device

    1

    Ethernet PHY line driver

    Current mode

    Voltage mode

    2

    Termination resistors

    Used 100E termination resistors between Tx+, Tx- and Rx+, Rx-

    No external termination resistors used

    3

    Center tap of the isolation T/F

    Center tap is connected to Vcc_2V5

    Center tap is connected to GND with 0.1uF capacitor

    4

    Speed

    Configured for 10/100 Mbps

    Configured for 10/100/1000 Mbps

    5

    Signal termination at RJ45 connector

    Pin 4 is GND, Pin 8 is Vcc_5V

    Used for 1000 Mbps

    6

    RJ45 connector

    Unshielded

    Shielded
  • 0 in reply to Girish Babu
    Prodigy 20 points

    Hi Alvaro,

    There are couple of queries regarding DP83867.

    1. Did DP83867 PHY will supports integrated magnetics RJ45 connector??

    2. Did this PHY will allow the combined center tap at the secondary side i.e PHY side??

    3. The datasheet says used integrated series termination resistors, what is the value of series termination resistance used for differential pairs?

    Thanks & Regards

    Girish

  • 0 in reply to Girish Babu
    TI__Mastermind 19621 points

    Hi Girish,

    I'm a little confused and have lost track of the main issue

    Girish Babu said:
    I can do the Auto-Negotiation to be Disabled but my host will support only 10BASE-T only. I mentioned below specifications of HOST and Device in detailed.

    If the host only supports 10BASE-T why were you trying to probe 1000 Mbps PAM-5 signals?

    Girish Babu said:

    1. Did DP83867 PHY will supports integrated magnetics RJ45 connector??

    2. Did this PHY will allow the combined center tap at the secondary side i.e PHY side??

    3. The datasheet says used integrated series termination resistors, what is the value of series termination resistance used for differential pairs?

    1. Yes, it does.

    2. No it does not

    3. I'm not sure exactly what you're asking here, could you try to clarify?

    Regards,

    Alvaro