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LAN9118 Family Programmer Reference Guide
SMSC AN 12.12 25 Revision 1.0 (12-14-09)
APPLICATION NOTE
Step Three:
Keep reading the MAC_CSR_CMD Register until the CSR Busy Bit =0.
Load the MII write command word (MII W/nR == 1) that is to be written to the MII ACC register into
the MAC_CSR_Data register. The command word will write the contents of the MII DATA register to
the PHY Advertisement register (0x4) (note that the lighter-shaded heading is expressed in MII ACC
register terms).
Step Four:
Write the command word into the MAC_CSR_CMD register. This causes the MII ACC register (0x06)
to be written (R/nW == 0) with the contents of the MAC_CSR_Data register, which in turn causes the
MII register write to be executed.
Steps 5-8:
5. Read the MAC_CSR_CMD Register until the Busy Bit = 0.
6. Load the MAC_CSR_CMD Register as follows: CSR Busy = 1, R/nW = 1 (Read), CSR Address
= 0x06 (MII_ACC Register)
7. Read the MAC_CSR_CMD Register until the Busy Bit = 0
8. Read the MAC_CSR_DATA Register. Repeat steps 6-8 until the MII Busy Bit (Bit 0) = 0.
Example 2: Read the PHY Status register (register 1)
Step One:
Load the MAC_CSR_Data register with the MII ACC register command word to read (MII W/nR == 1)
PHY register 1 (MII Register == 1). Note that the lighter-shaded heading is expressed in MII ACC
terms.
Step Two:
Write the command word into the MAC_CSR_CMD register. This causes the contents of the
MAC_CSR_Data register to be written (R/nW == 0) to the MII ACC register (0x06), which executes
the PHY read. The resulting read from the PHY is then loaded to the MII Data register
MAC_CSR_DATA (TO BE LOADED INTO MII ACC REGISTER)
Reserved
(31:16)
PHY Address
(15:11)
MII Register
(10:6)
Reserved
(5:2)
MII
W/nR
MII
Busy
0x1 0x4 1 1
MAC_CSR_CMD (ACCESSING MII_ACC REGISTER)
CSR Busy R/nW Reserved (29:8) CSR Address (7:0)
1 0 0x06
MAC_CSR_DATA
Reserved
(31:16)
PHY Address
(15:11)
MII Register
(10:6)
Reserved
(5:2)
MII
W/nR
MII
Busy
0x1 0x1 0 1