NUC920ABN Datasheet, PDF (129/529 Pages) Nuvoton Technology Corporation – 32-BIT ARM926EJ-S BASED MCU

NUC920ABN
32-BIT ARM926EJ-S BASED MCU
[19]
MDCON
[18]
PreSP
[17]
BUSY
[16]
Write
[12:8] PHYAD
[4:0]
PHYRAD
MDC Clock ON Always
The MDC controls the MDC clock generation. If the MDCON is set to high, the
MDC clock actives always. Otherwise, the MDC will only active while S/W
issues a MII management command.
1’b0: The MDC clock will only active while S/W issues a MII management
command.
1’b1: The MDC clock actives always.
Preamble Suppress
The PreSP controls the preamble field generation of MII management frame.
If the PreSP is set to high, the preamble field generation of MII management
frame is skipped.
1’b0: Preamble field generation of MII management frame is not skipped.
1’b1: Preamble field generation of MII management frame is skipped.
Busy Bit
The BUSY controls the enable of the MII management frame generation. If
S/W wants to access registers of external PHY, it set BUSY to high and EMC
generates the MII management frame to external PHY through MII
Management I/F. The BUSY is a self-clear bit. This means the BUSY will be
cleared automatically after the MII management command finished.
1’b0: The MII management has finished.
1’b1: Enable EMC to generate a MII management command to external PHY.
Write Command
The Write defines the MII management command is a read or write.
1’b0: The MII management command is a read command.
1’b1: The MII management command is a write command.
PHY Address
The PHYAD keeps the address to differentiate which external PHY is the
target of the MII management command.
PHY Register Address
The PHYRAD keeps the address to indicate which register of external PHY is
the target of the MII management command.
MII Management Function Frame Format
In IEEE Std. 802.3 clause 22.2.4, the MII management function is defined. The MII management function
is used for the purpose of controlling the PHY and gathering status from the PHY. The MII management
frame format is shown as follow.
READ
WRITE
PRE
1…1
1…1
Management frame fields
ST OP PHYAD REGAD TA DATA
01 10 AAAAA RRRRR Z0 DDDDDDDDDDDDDDDD
01 01 AAAAA RRRRR 10 DDDDDDDDDDDDDDDD
IDLE
Z
Z
Publication Release Date: Jun. 18, 2010
129
Revision: A3