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12.3.3
MIIM (Media Independent Interface Management)
12.3.3.1 MIIM Control Register
The MIIM control register allows the C790 to read and write any one of the PHYs connected
to the MAC. This register provides bits to address a particular PHY, to address a register, to
set the read or write direction, and to indicate that the read or write is still in progress. Upon
the completion of reset, this register's value is 0x0000_0000.
63
31
Table 12-31 MIIM Control Register Field Descriptions
Bit(s)
Field
15:11
PA[4:0]
10:6
REG[4:0]
5:2
-
1
Write
Busy
0
(Read)
TX7901 User's Manual (Rev. 6.30T – Nov, 2001)
Chapter 12: 10/100 IEEE802.3 Media Access Controller
0
16
Figure 12-3 Fields of MIIM Control Register
PHY Address
The 5-bit address of the PHY being read or written
Register Address
The 5-bit address of the MIIM register being read or written
Reserved
MIIM Write
When set, indicates that this is a write operation on the PHY with the data in the MIIM data register
MIIM Busy
When set, indicates a MIIM management read or write operation. If the Busy bit is set, writes to the
MIIM Control or Data Register are ignored. The Busy bit should be 0 when writing to these registers.
(Note : The MIIM data register must contain valid transmit data prior to writing to this MIIM Control
Register)
0
32
16
15
11
10
PA
5
Description
12-33
6
5
2
REG
0
5
4
32
1
0
Wri
Bu
te
sy
1
1
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