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Fast Ethernet Controller (FEC)
MCF52235 ColdFire® Integrated Microcontroller Reference Manual, Rev. 6
18-28
Freescale Semiconductor
18.5.4.6
MII Management Frame Register (MMFR)
The MMFR is accessed by the user and does not reset to a defined value. The MMFR register is used to
communicate with the attached MII compatible PHY device(s), providing read/write access to their MII
registers. Performing a write to the MMFR causes a management frame to be sourced unless the MSCR
has been programmed to 0. In the case of writing to MMFR when MSCR equals 0, if the MSCR register
is then written to a non-zero value, an MII frame is generated with the data previously written to the
MMFR. This allows MMFR and MSCR to be programmed in either order if MSCR is currently zero.
Before accessing the MII registers via the MMFR, the software must poll EIR[MII] to make sure that an
access is not currently in progress.
Figure 18-9. MII Management Frame Register (MMFR)
To perform a read or write operation on the MII Management Interface, the MMFR register must be
written by the user. To generate a valid read or write management frame, the ST field must be written with
IPSBAR
Offset: 0x1040 (MMFR)
Access: User read/write
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
R
ST
OP
PA
RA
TA
W
Reset
Undefined
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
R
DATA
W
Reset
Undefined
Table 18-17. MMFR Field Descriptions
Field
Description
31–30
ST
Start of frame delimiter. These bits must be programmed to 01 for a valid MII management frame.
29–28
OP
Operation code. This field must be programmed to 10 (read) or 01 (write) to generate a valid MII
management frame. A value of 11 produces read frame operation while a value of 00 produces write
frame operation, but these frames are not MII compliant.
27–23
PA
PHY address. This field specifies one of up to 32 attached PHY devices.
22–18
RA
Register address. This field specifies one of up to 32 registers within the specified PHY device.
17–16
TA
Turn around. This field must be set to 10 to generate a valid MII management frame.
15–0
DATA
Management frame data. This is the field for data to be written to or read from the PHY register.
Because
of
an
order
from
the
United
States
International
Trade
Commission,
BGA-packaged
product
lines
and
part
numbers
indicated
here
currently
are
not
available
from
Freescale
for
import
or
sale
in
the
United
States
prior
to
September
2010:MCF52234CVM60,
MCF52235CVM60