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MDIO Registers

4.12 MDIO User Access Register 0 (USERACCESS0)

The MDIO user access register 0 (USERACCESS0) is shown in Figure 26 and described in Table 25.

Figure 26. MDIO User Access Register 0 (USERACCESS0)

31

30

29

28

26

25

21

20

16

GO

WRITE

ACK

 

Reserved

 

REGADR

 

PHYADR

R/WS-0

R/W-0

R/W-0

 

R-0

 

R/W-0

 

R/W-0

15

 

 

 

 

 

 

 

0

 

 

 

 

 

 

DATA

 

 

 

 

 

 

 

 

R/W-0

 

 

LEGEND: R = Read only; R/W = Read/Write; R/WS = Read/Write 1 to set; -n= value after reset

 

 

Table 25. MDIO User Access Register 0 (USERACCESS0) Field Descriptions

Bit

Field

Value

Description

31

GO

 

Go bit. Writing a 1 to this bit causes the MDIO state machine to perform an MDIO access when it is

 

 

 

convenient for it to do so; this is not an instantaneous process. Writing a 0 to this bit has no effect.

 

 

 

This bit is writeable only if the MDIO state machine is enabled. This bit will self clear when the

 

 

 

requested access has been completed. Any writes to the USERACCESS0 register are blocked

 

 

 

when the GO bit is 1.

30

WRITE

 

Write enable bit. Setting this bit to a 1 causes the MDIO transaction to be a register write, otherwise

 

 

 

it is a register read.

 

 

0

The user command is a read operation

 

 

1

The user command is a write operation

29

ACK

 

Acknowledge bit. This bit is set if the PHY acknowledged the read transaction.

28-26

Reserved

0

Reserved

25-21

REGADR

 

Register address bits. This field specifies the PHY register to be accessed for this transaction

20-16

PHYADR

 

PHY address bits. This field specifies the PHY to be accesses for this transaction

15-0

DATA

 

User data bits. These bits specify the data value read from or to be written to the specified PHY

 

 

 

register.

SPRU975B –August 2006

Ethernet Media Access Controller (EMAC)/Management Data Input/Output (MDIO)

77

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Texas Instruments TMS320C645x DSP manual Mdio User Access Register 0 USERACCESS0