
6-12
MPC860T (Rev. D) Fast Ethernet Controller Supplement
MOTOROLA
PRELIMINARYÑSUBJECT TO CHANGE WITHOUT NOTICE
Table 6-13 describes X_DES_ACTIVE Þelds.
6.2.13 MII Management Frame Register (MII_DATA)
The MII_DATA register, shown in Figure 6-13, is used to communicate with the attached
MII-compatible PHY device, providing read/write access to their MII registers. Writing to
MII_DATA causes a management frame to be sourced unless MII_SPEED was cleared; in
this case, if MII_SPEED is then written to a non-zero value and an MII frame is generated
with the data previously written to MII_DATA. This allows MII_DATA and MII_SPEED
to be programmed in either order if MII_SPEED is currently zero. MII_DATA is accessed
by the user and does not reset to a deÞned value.
Bits
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
Field
Ñ
X_DES_ACTIVE
Ñ
Reset
0000_0000_0000_0000
R/W
Read/write
Addr
0xE54
Bits
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
Field
Ñ
Reset
0000_0000_0000_0000
R/W
Read/write
Addr
0xE56
Figure 6-12. X_DES_ACTIVE Register
Table 6-13. X_DES_ACTIVE Field Descriptions
Bits
Name
Description
0Ð6
Ñ
Reserved.
7
X_DES_ACTIVE Set when this register is written, regardless of the value written. Cleared whenever no
additional ready descriptors remain in the transmit ring.
8Ð31
Ñ
Reserved.
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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