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DP83822I: Register Setting Questions

Kazuki Itoh
Genius 11090 points
Part Number: DP83822I


Tool/software:

Hi team,

I have questions regarding the register settings for the DP83822.

[Question 1]
I believe there is no need to change BIT[4:0] of the ANAR register (0x0004) from 0x01.
However, if a value other than 0x01 is set, would any issues occur?
(For example, failure to establish link with the link partner, etc.)

[Question 2]
My board configures Auto-Negotiation through hardware strapping.
Based on this assumption, is it okay to assume that the link with the link partner can be established even without explicitly setting the Auto-Negotiation bit by writing 0x1200 to BMCR (0x00) at startup?
Also, even if Auto-Negotiation is configured by hardware strapping, is it still necessary to always write 0x1200 to BMCR (0x00) at startup?

Best regards,

Kazuki Itoh

  • 0
    TI__Mastermind 20156 points

    Hi Itoh-san, 

    Kazuki Itoh said:
    [Question 1]
    I believe there is no need to change BIT[4:0] of the ANAR register (0x0004) from 0x01.
    However, if a value other than 0x01 is set, would any issues occur?
    (For example, failure to establish link with the link partner, etc.)

    0x0004[4:0] is protocol selection bits. Selecting other than 0x01 may change the protocol from IEEE 802.3u. 


    Kazuki Itoh said:
    [Question 2]
    My board configures Auto-Negotiation through hardware strapping.
    Based on this assumption, is it okay to assume that the link with the link partner can be established even without explicitly setting the Auto-Negotiation bit by writing 0x1200 to BMCR (0x00) at startup?
    Also, even if Auto-Negotiation is configured by hardware strapping, is it still necessary to always write 0x1200 to BMCR (0x00) at startup?

    If auto-negotiation is configured through hardware strapping, there is no need to write 0x1200 to BMCR at startup. 

    Best,

    J