TLK10031: MDIO port without response

Yaoting Yang

Part Number: TLK10031

Hi,

We are using TI’s TLK10031 10G Ethernet Transceiver as a phy-layer chip to interface an FPGA XAUI port. I am stuck at its MDIO port. There is no response when read it. It looks like floating (all "1”s). I have checked the chip's reset pin (H5) as well as channel power down pin(A8). They are all logic high(=1.8V). The MDIO waveform meets the MDIO-C45 standard with MDC of 5MHz . The port has a pull up resistor of 2K. ST pin(M9) is pull down to ground via a 10K resistor. All power supply voltages look right (within 5%).

Do you have any suggestion for it?

Appreciate a lot!

over 6 years ago

0 Luis Omar Moran over 6 years ago

TI__Genius 16150 points

Hi Yaoting,

Please try the default value for PRTAD[4:1] = 4b'0000, since it seems you have tied to VDD.

Best Regards,
Luis Omar Moran
High Speed Interface
SWAT Team

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

Intellectual 780 points

Thank you, Luis.

The PRTAD[4:0] (= 5'b00000) is matched to pin setting. Pin M8,J6,L9,G9,E10 are all tied to ground. This is current setting with the problem. They are not tied to VDD.

0 Yaoting Yang over 6 years ago in reply to Yaoting Yang

Intellectual 780 points

This is current setting.

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

TI__Genius 16150 points

Hello Yaoting,

Could your verify the "preamble" parameter for the MDIO communication, since the standard specifies 32 "1s" for this parameter, the preamble actually needs to be 33 bits long. In applications that hold the MDIO bus idle (high) while the MDC continues to run (i.e. between commands) this problem doesn't show up, but if you are only sending MDC edges when needed for MDIO then it could be an issue. (The fix would just be to modify your MDIO drivers to accommodate the extra pre-amble bit).

I hope this helps.

Best Regards,

Luis Omar Moran

High Speed Interface

SWAT Team

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

Intellectual 780 points

Yes. My preambles are 34 MDC cycles.
I found the MDIO waveform is abnormal. Its logical LOW is not going to ground and unstable. Since i don't know how to attach my oscilloscope's snap-shot in reply, i opened another issue in this forum today,called " MDIO line is (not) going to ground". Please check.

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

TI__Genius 16150 points

The issue is handled through another post.

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TLK10031: MDIO port without response