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DP83TC811R-Q1: Start-Up

David Castillo
Prodigy 20 points
Part Number: DP83TC811R-Q1
Other Parts Discussed in Thread: DP83TC811

Hello, 

we are working with DP83TC811R-Q1 connected with LAN7801 device. I would like to configure DP83TC811R-Q1 register in order to have ethernet interface available after POR.

I checked computer detects ethernet interface once LED0_GPIO is up. I got it setting register 16h (BIST Control Register) to 0x102 value. What it's confusing for me is last 2 bits are 'reserved' based on datasheet documentation:

I would need a way to configure PHY in normal operation (not loopback tests) and having the 'Link status' up.

Best Regards,

David

  • 0
    TI__Genius 12745 points

    Hi David,

    Is the issue the PHY powers up in loopback mode or that register 0x16=0x102?  Is the PHY properly detecting link (both on the 811 and LAN side)?

    What do you mean the computer interface detects Ethernet interface once LED0 is up? Do you mean once it lights up or once it latches to the correct strap? How are you measuring when LED0 is up?

    There will be some delay between when the PHY powers up (through VDD) and the MDC/MDIO interfadce is available. See the specs below from the datasheet (you can click the image to zoom in).

    Best regards,

    Melissa

  • 0 in reply to Melissa Chang
    Prodigy 20 points

    Hello Melissa, I will summarize the points we would need:

    1) We would like to stablish Ethernet connection to 100Mbits between MAC(LAN7801) and DP83TC811R-Q1 device.

    2) We would like to configure register for both devices properly. Once board is powered on, register shall be loaded from the external EEPROM. Question: which register from DP83TC811R-Q1 shall be configured to work with this device properly to 100MBit/s? 

    3) In order to have linkup of DP83TC811R-Q1 device, I followed this document: 'DP83TC811 Configuring for Open Alliance Specification', where in section '3 Software Configuration' describes all the steps to configure this device as Master/Slave'. Once I perform these steps, I get DP83TC811R-Q1 linkup (LED0 enable), and from that moment, windows detects this ethernet interface, and I can communicate by 100Mbits/s.

    Question similar to step2: How could we follow this steps register to be done automatically once device is powered on? 

    Best Regards,

    David

  • 0 in reply to David Castillo
    TI__Genius 12745 points

    Hi David,

    The DP83TC811 has to be programmed with the registers mentioned in the document DP83TC811 Configuring for Open Alliance Specification in order to pass Open Alliance. The DP83TC811 will not be able to pass compliance without these register writes. Note this init scripts stops the PHY from linking up until after the script finishes.

    If you want the PHY to automatically try to establish a link with a valid Link Partner once POR is complete, you can set the PHY to autonomous mode through straps or register 0x18B. For automatic link up, you should also check your have the correct master/slave configuration. 

    David Castillo said:
    2) We would like to configure register for both devices properly. Once board is powered on, register shall be loaded from the external EEPROM. Question: which register from DP83TC811R-Q1 shall be configured to work with this device properly to 100MBit/s? 

    Does your external EEPROM support MDIO/MDC? If so, you should program the registers mentioned in the document DP83TC811 Configuring for Open Alliance Specification.The DP83TC811 only supports 100Mbps, so it will power up in that mode by default.

    Best regards,

    Melissa