DP83826E: DP83826 Etherne Phy sends data without link

Hi Tobias,

Is auto-negotiation disabled on the PHY? Have you done any register configuration to the PHY besides default? Can you send a snapshot of the signal present on the line?

Thanks,

David

Hi David,

we used the same PHY configuration as mentioned in this thead:

https://e2e.ti.com/support/interface-group/interface/f/interface-forum/1124225/dp83826i-no-ethernet-communication-possible-with-sitara-am243x

auto-negotiation should be enabled but as mentioned in the thread above the auto-negotiation bit is 0 at startup and toggles after link detection.

I will check with my colleagues that did the signal-measurement if we can reproduce it another time and provide a snapshot for you.

Best regards

Alex

Hi David,

this is what our colleagues measured:

Best regards

Alex

Hi Alex,

Register 0x468 shows auto-negotiation is not enabled. 

Please try switching strap0 (pin 16) to mode 0. Let me know the results.

Thanks,

David

Hi David,

I'm a bit confused:

Following the datasheet on PIN strapping, the strap 0 should be set to 1 to enable auto-negotiation:

If I understand the datasheet correctly register 467h shows the state of the strap-pins, where the strap0 seems to be 1. What's the purpose of switching that strap to 0?

Our hardware ist currently in use to proceed with our urgent software integration. We wanted to report this behaviour to see if there is an explanation for that or if there could be something wrong with our hardware.

Best regards

Alex

Hi David,

we changed the Step0 to 0 and the Register Dump looks fine now:

PHY 3 Register Dump
Register 0000 is: 3100
Register 0001 is: 786D
Register 0002 is: 2000
Register 0003 is: A131
Register 0004 is: 01E1
Register 0005 is: CDE1
Register 0006 is: 000F
Register 0007 is: 2001
Register 0008 is: 0000
Register 0009 is: 0000
Register 000A is: 0100
Register 000B is: 040B
Register 000C is: 0000
Register 000D is: 401F
Register 000E is: 0004
Register 000F is: 0000
Register 0010 is: 0615
Register 0011 is: 0108
Register 0012 is: 6400
Register 0013 is: 2800
Register 0014 is: 0000
Register 0015 is: 0000
Register 0016 is: 0100
Register 0017 is: 0041
Register 0018 is: 0480
Register 0019 is: CC03
Register 001A is: 0000
Register 001B is: 007D
Register 001C is: 05EE
Register 001D is: 0000
Register 001E is: 0102
Register 0467 is: 00CE
Register 0468 is: 2587

Can the disabled auto-negotiation be the reason for the signal we were measuring in our first mentioned tests?

Best regards

Alex

Hi Alex,

Yes, this explains your issue.

Thanks,

David