DP83869HM: Packet loss problems

Korey Holmstrom

Part Number: DP83869HM
Other Parts Discussed in Thread: DP83867E, , DP83869

Hello,

I have a design which previously used the DP83867E package in a RGMII to copper configuration, but have since replaced it with a DP83869HM. When operating with the DP83867E, I saw no packet loss and was able to run at 100/1000 without issue. After changing the PHY to the DP83869HM package, I initially had some issues with my driver but found that in register 0x32, the RGMII_TX_CLK_DELAY and RGMII_RX_CLK_DELAY bits are swapped between the two packages. After correcting the new register layout, the driver was able to attach to the PHY but I am now seeing as much as 30% packet loss on a 100Mb connection and even more on 1000Mb. I have swapped my previous design with the DP83867E into my setup to verify my current cabling/network and it can still communicate without issue.

Comparing the two datasheets, I'm having a difficult time determining why the DP83869HM package is having packet loss problems. Is there additional configuration required for the DP83869HM that wasn't necessary for the DP83867E that I am neglecting to set?

over 2 years ago

0 Gerome Cacho over 2 years ago

TI__Mastermind 27885 points

Hello Korey,

When you swapped the DP83867 for the DP83869, did you ensure that you changed the layout of your design to match the pinout of DP83869? These boards are not pin-to-pin compatible.

Sincerely,
Gerome

0 Korey Holmstrom over 2 years ago in reply to Gerome Cacho

Prodigy 10 points

Hi Gerome,

Yes, the board layout was modified per the DP83869HM datasheet pin layout with the appropriate pin strapping. Care was taken to ensure the trace lengths were maintained between the designs on the TX/RX signal wires. The MDIO and MDC trace lengths did increase by 107 and 164 mils respectively. Though I would not expect the management interface to affect the packet loss unless I am mistaken?

0 Gerome Cacho over 2 years ago in reply to Korey Holmstrom

TI__Mastermind 27885 points

Hi Korey,

I am looking into your last question. In the meanwhile, have you tried the DP83869 driver available here?

https://www.ti.com/tool/ETHERNET-SW

Sincerely,

Gerome

0 Korey Holmstrom over 2 years ago in reply to Gerome Cacho

Prodigy 10 points

Thanks for the link to the drivers, these did not come up as I was researching the problem - I'll try taking a look at the driver.

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DP83869HM: Packet loss problems