AR# 70686

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Strap work-around for getting stable PHY link when used in RGMII or SGMII mode on Evaluations boards with a TIDP83867

Description

How do I get a stable PHY link while using Xilinx evaluations boards that have a TIDP83867 PHY link in RGMII or SGMII mode?

Solution

Many of our evaluation boards use the TIDP83867 PHY link for Ethernet communications at 10 Mb/s, 100 Mb/s, or 1000 Mb/s.

On boards with this configuration, RX_CTRL has a pull down of 1K and so is set to Strap Mode 1.

RX D0 is set to Mode 1 with Pulldown of 1K, RX D2 is set to Mode 4 with pullup to 1K resulting in PHY Addr 5b01100.

But per the documentation linked to below, modes 1 and 2 are not applicable to RX_CTRL and it should be configured to strap MODE 3 or 4 only.

This applies to both the RGMII and SGMII PHY versions and can be found in the datasheets linked below:

http://www.ti.com/lit/ds/symlink/dp83867ir.pdf (Page 49)

http://www.ti.com/lit/ds/symlink/dp83867e.pdf (Page 36)

If RX_CTRL is not strapped to mode 3 or 4, a software work-around sequence is needed:

  • For RGMII, Reg 0x31 Bit[7] = 0
  • For SGMII, Reg 0x31 Bit[8] = 1, Bit[7] = 0 and Bits[6:5] = 0b11

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AR# 70686
Date 05/31/2019
Status Active
Type General Article
Devices
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