DP83867IR: RX_CTRL signal voltage levels

Sanjeev Karaiyan

Part Number: DP83867IR

Hello,

What are the valid voltage levels of RX_CTRL signal?

I see the following description in datasheet

"the received data available and receive error are combined(RXDV_ER) using both rising and falling edges of the receive clock(RX_CLK)"

I see 1.8v pulses and ~1v pulses on this pin. Does 1.8v pulses correspond to valid packets? Does 1v pulses mean RX_ER?

Thanks,

Sanjeev Karaiyan

over 5 years ago

0 Rob Rodrigues over 5 years ago

TI__Mastermind 19780 points

Hi Sanjeev,

The RX_DV logic level is presented on the rising edge of RX_CLK. The RX_ER logic level is presented on the falling edge of the RX_CLK.

From the RGMII v2.0 spec:

You should not see 1V pulses. This means something is wrong with the PHY, the MAC, or the probing of the signal lines.

Best Regards,

0 Sanjeev Karaiyan over 5 years ago in reply to Rob Rodrigues

TI__Expert 6740 points

Hello Rob,

I want some clarification on the case of receiving a valid frame with errors. Does the RX_CTRL signal keeps on toggling every edge of the RXC clock for the entire duration of the frame?

More observations on the 1V pulse issue:
1. I replaced the probes and scopes with higher bandwidth versions. Still same behavior is seen.
2. The 1V pulse issue on RX_CTRL is not seen for every received frame. It occurs for random frames (so far couldn't find any pattern)
3. The issue sometimes starts in between reception of a frame such that the 1.8V level jumps down to 1V. Sometimes it occurs for entire duration of a frame.
4. I could see this issue in different boards also. So not a board fault.

Thanks,
Sanjeev

0 Rob Rodrigues over 5 years ago in reply to Sanjeev Karaiyan

TI__Mastermind 19780 points

Hi Sanjeev,

No, the RX_CTRL signal only toggles on the errored byte. If you are seeing constantly RX_CTRL toggling, then you have something wrong with your HW, or your link partner has a very high amount of jitter.

Do you have a schematic you can share?

Best Regards,

0 Sanjeev Karaiyan over 5 years ago in reply to Rob Rodrigues

TI__Expert 6740 points

Hello Rob,

This problem is seen with PHYs on industrial ethernet daughter card of AM654x IDK. www.ti.com/.../tmdx654idkevm

Thanks,
Sanjeev

0 Rob Rodrigues over 5 years ago in reply to Sanjeev Karaiyan

TI__Mastermind 19780 points

Hi Sanjeev,

Supporting by email. Will bring solution to this thread.

Best,

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DP83867IR: RX_CTRL signal voltage levels