DP83867CSRGZ datasheet(29/129 Pages) TI2

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7.4.2.1 Extended Address Space Access

The DP83867's SMI function supports read or write access to the extended register set using registers REGCR

(0x0D) and ADDAR (0x0E) and the MDIO Manageable Device (MMD) indirect method defined in IEEE 802.3ah

Draft for clause 22 for accessing the clause 45 extended register set.

The standard register set, MDIO registers 0 to 31, is accessed using the normal direct-MDIO access or the

indirect method, except for register REGCR (0x0D) and ADDAR (0x0E), which is accessed only using the

normal MDIO transaction. The SMI function ignores indirect accesses to these registers.

REGCR (0x0D) is the MDIO Manageable MMD access control. In general, register REGCR(4:0) is the device

address DEVAD that directs any accesses of ADDAR (0x0E) register to the appropriate MMD.

The PHY’S supports one MMD device address. The vendor-specific device address DEVAD[4:0] = 11111 is used

for general MMD register accesses.

All accesses through registers REGCR and ADDAR must use the correct DEVAD. Transactions with other

DEVAD are ignored. REGCR[15:14] holds the access function: address (00), data with no post increment (01),

data with post increment on read and writes (10) and data with post increment on writes only (11).

Table 7-3. REGCR DEVAD Functions

REGCR[15:14]

Function

Accesses to register ADDAR modify the extended register ‘set address’ register. This address register must always

be initialized to access any of the registers within the extended register set.

Accesses to register ADDAR access the register within the extended register set selected by the value in the

address register.

Access to register ADDAR access the register within the extended register set selected by the value in the address

read accesses, the value of the address register remains unchanged.

The following sections describe how to perform operations on the extended register set using register REGCR

and ADDAR. The descriptions use the device address for general MMD register accesses (DEVAD[4:0] = 11111).

7.4.2.1.1 Write Address Operation

1. Write the value 0x001F (address function field = 00, DEVAD = 31) to register REGCR.

2. Write the desired register address to register ADDAR.

Subsequent writes to register ADDAR (step 2) continue to write the address register.

7.4.2.1.2 Read Address Operation

To read the address register:

1. Write the value 0x001F (address function field = 00, DEVAD = 31) to register REGCR.

2. Read the register address from register ADDAR.

7.4.2.1.3 Write (No Post Increment) Operation

To write a register in the extened register set:

Instruction

Example: Set reg 0x0170 = 0C50

1. Write the value 0x001F (address function field = 00, DEVAD = 31)

to register REGCR (0x0D).

Write register 0x0D to value 0x001F

2. Write the desired register address to register ADDAR (0x0E).

Write register 0x0E to value 0x0170

3. Write the value 0x401F (data, no post increment function field =

01, DEVAD = 31) to register REGCR.

Write register 0x0D to value 0x401F

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DP83867CS, DP83867IS, DP83867E

SNLS504F – OCTOBER 2015 – REVISED JANUARY 2025

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