DP83822I: the role of PHY address

Noriyuki Takahashi

Genius 11860 points

Part Number: DP83822I

Hi team

Customer wants to understand the role of PHY address.

The address is set through bootstrap configuration. But not sure what the address is used for.

Could you tell when the address is used in the system?

Regards,

Noriyuki Takahashi

over 6 years ago

0 Hung Nguyen92 over 6 years ago

TI__Expert 5670 points

Hi Takahashi-san,

The role of PHY address is to have unique identification in the system, especially when there are multiple PHY devices in that system.

Regards,

Hung Nguyen

0 Noriyuki Takahashi over 6 years ago in reply to Hung Nguyen92

TI__Genius 11860 points

Hung,

Thanks. Please let me ask basic questions again.

PHY address can be read through SMI, that is , MDC/MDIO?

Regards,

Noriyuki Takahashi

0 Hung Nguyen92 over 6 years ago in reply to Noriyuki Takahashi

TI__Expert 5670 points

Hi Takahashi-san,

The PHY address cannot be read through MDC/MDIO.

However, you can strap the device to a desired PHY address. In order to access the device, you need to specify the PHY address in the MDC/MDIO protocol.

See section "8.4.2 Serial Management Interface" of the datasheet for more info.

Regards,

Hung Nguyen

0 Noriyuki Takahashi over 6 years ago in reply to Hung Nguyen92

TI__Genius 11860 points

Hung

The PHY address cannot be read through MDC/MDIO.

--> Is this true? Looking at Table 39. 0x0019 PHY Control Register (PHYCR), PHY address's type is the Read Only Mode.

Regards,

Noriyuki Takahashi

0 Hung Nguyen92 over 6 years ago in reply to Noriyuki Takahashi

TI__Expert 5670 points

Hi Takahashi-san,

I'm not sure I understand your concern with Table 39 regarding to the PHY address.

Again, the PHY address cannot be read through MDC/MDIO. The PHY address is predefined by the strap.

When you read or write any register of the PHY, you need to specify the known PHY address in the protocol. See section 8.4.2 Serial Management Interface for more details.

Regards,

Hung Nguyen

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DP83822I: the role of PHY address