Auto-negotiation fails for KSZ8081RNA interface

[MMB]

I'm using a board that has MIMXRT1021 interfaced with KSZ8081RNA.

I'm using MCUExpresso IDE and LPC Link 2 for debugging.

While trying to run lwip_ping_bm example from SDK_2.x_MIMXRT1020-EVK, I get the error "PHY Auto-negotiation failed" error and link fails.

I checked that MDC clock is 2.5 MHz, there is data on MDIO line while PHY_Read and PHY_Write operations. Reset timing requirement is also met. Please help.

[jeremyzhou]

Hi，
Thank you for your interest in NXP Semiconductor products and for the opportunity to serve you.
I'd like to know what exactly board you tested with, the lwip_ping_bm runs well on my MIMXRT1020-EVK board actually.
Have a great day,
TIC

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[MMB]

Hi, I'm using a custom board that has MIMXRT1021 interfaced with KSZ8081RNA (not KSZ8081RNB as in EVK Board). PHY address is configured as per our schematic design, clock and reset signals are fine. Are there any other checkpoints that I need to verify?

[jeremyzhou]

Hi，
Thanks for your reply.
From my experience, I'd like to suggest you compare the datasheets between the KSZ8081RNA and KSZ8081RNB to figure out the cause of lwip_ping_bm failing to initialize the KSZ8081RNA.
Have a great day,
TIC

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[MMB]

Hi,

There is one difference between our custom board and MIMXRT1020-EVK board regarding Ethernet interface.

EVK:

50MHz from ENET_TX_CLK (from MCU) as input to PHY

Custom board:

25MHz crystal clock as input to PHY. And 50MHz ENET_REF_CLK from PHY provided as input to MCU's MAC.

The PHYCT2 register Bit 7 is set to 0.

IOMUXC_GPR_GPR1 Bit 17 is set to 0.

After making these changes, auto-negotiation is completed and link is up. And ping response is also received, but with more than 50% packet loss.

Are we missing any more configurations regarding this?

[jeremyzhou]

Hi,
Thanks for your reply.
I was wondering if you can share the schematic of your customize board, then, I'd like to suggest you use Wireshark to capture the data when running the lwip_ping_bm demo.
Lastly, compare the datasheets between the KSZ8081RNA and KSZ8081RNB to check whether miss something during initializing the KSZ8081RNA.
Have a great day,
TIC

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Note:
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- We are following threads for 7 weeks after the last post, later replies are ignored
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