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DP83TC812S-Q1: DP83TC812S-Q1 TX Packet Counters not incrementing

Ethan Reiland
Prodigy 20 points

Part Number: DP83TC812S-Q1

Hello!

I am having trouble reading from the TX packet count registers (0x0639, 0x063A, 0x063B). We’ve been unable to get these to read anything other than 0. We’ve confirmed traffic is being sent out the PHY, and we can see the equivalent counters for RX incrementing as expected when packets are received.

Is this a known issue? Is there undocumented behavior around register access order or timings? I’m assuming there likely isn’t, but I just wanted to check before we continue troubleshooting.

  • 0
    TI__Genius 9193 points

    Hi Ethan,

    There is no known issues with TX packet counter not incrementing. The correct procedure is to read 0x639-0x63B sequentially (I'm assuming you are already doing this because you see RX packet counters incrementing). 

    The TX packet counter not incrementing points to a MAC interface issue. What is the MAC interface? Is the PHY strapped correctly to the corresponding MAC mode? 

    Best,

    Charles

  • 0 in reply to Charles
    Prodigy 20 points

    We've tried reading in sequence (as well as in reverse, and in other orders). The MAC interface is strapped correctly seems to be behaving as expected. We are able to see packets in/egressing from the PHY as expected.

    It looks like we were able to get the counter working by enabling the PRBS checker (0x0619[2] = 1). I don't exactly understand the connection between the PRBS and these TX counters, is there some other part of this configuration that might be botched and is causing this?

  • 0 in reply to Ethan Reiland
    TI__Genius 9193 points

    Hi Ethan, 

    I am seeing similar behavior on my 812 EVM. I send packets from my PC. With 0x0619[2] = 0, I see TX packet counters increment and RX packet counters stuck at 0.   

    My suggestion is to leave 0x0619[2] as its default value of 1. In which part of your configuration are you turning PRBS checker off?

    Best,

    Charles