TLK10031: MDIO line is going to ground

Yaoting Yang

Part Number: TLK10031

Hi,

I found the MDIO waveform is abnormal. Its logical LOW is not going to ground and unstable. Attached please find out the oscilloscope’s snap shot. The upper one is MDIO line to TI’s transceiver and lower one is MDC. VDDO=1.8V. Why?

Please help?

Appreciate a lot!TEK00001.TIF

over 6 years ago

0 Luis Omar Moran over 6 years ago

TI__Genius 16150 points

Hello Yaoting,

Are you placing a pull-up resistor of 2k for the MDIO signal?

Regards,

Luis

0 Yaoting Yang over 6 years ago in reply to Luis Omar Moran

Intellectual 780 points

Yes.

0 Luis Omar Moran over 6 years ago in reply to Yaoting Yang

TI__Genius 16150 points

1. Please verify the cable for MDIO communication.

2. What is your current configuration of ST, MODE_SEL and PRTAD[4:0]?

Regards,

Luis

0 Yaoting Yang over 6 years ago in reply to Luis Omar Moran

Intellectual 780 points

Hi Luis,
Thanks for your reply. I have checked all pin setting. They are all correct.
Strangely after adding one more pre-amble bit (to 33 bits rather than 32 bit as usual ) the mdio is working now and line floating issue disappeared.
Now i come up with a new problem. The TLK10031 is no response to fiber link at all. I wrote another thread of question for it. can you help me?
Yaoting

0 Luis Omar Moran over 6 years ago in reply to Yaoting Yang

TI__Genius 16150 points

Hello Yaoting,

I will be answering in the other e2e thread.

https://e2e.ti.com/support/interface/high_speed_interface/f/138/t/593975

Best Regards,
Luis

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TLK10031: MDIO line is going to ground