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Ethernet Physical Transceiver (EPHY)
MCF52235 ColdFire® Integrated Microcontroller Reference Manual, Rev. 6
Freescale Semiconductor
19-9
19.3.3.1
EPHY Control Register
Figure 19-6. Control Register
MII Register Address: 0x00
Access: User read/write
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
R
RESET
LOOP
BACK
DATA
RATE
ANE
PDWN
ISOL
RAN
DPLX
COL
TEST
0
0
0
0
0
0
0
W
Reset
0
0
1
X
0
0
0
1
0
0
0
0
0
0
0
0
Table 19-6. Control Register Field Descriptions
Field
Description
15
RESET
EPHY Reset bit. Resetting a port is accomplished by setting this bit to 1.
1 The PHY resets the port’s status and registers to the default values. The PHY also resets the PHY
to its initial state. After the reset is complete, the PHY clears this bit automatically. The reset
process is completed within 1.3 ms of this bit being set. While the preamble is suppressed, the
management interface must not receive an ST within three MDC clock cycles following a software
reset.
0 No effect
14
LOOPBACK
Digital Loopback Mode bit. Determines Digital Loopback Mode
1 Enables digital loopback mode. Port is placed in loopback mode. Loopback mode allows the TXD
data to be sent to the RXD data circuitry within 512 bit times. The PHY is isolated from the medium
(no transmit or receive to the medium allowed) and the MII_COL signal remains de-asserted,
unless this bit is set.
0 Disables digital loopback mode
13
DATARATE
Speed Selection bit. The link speed is selected through the auto-negotiation process or
by manual
speed selection. ANE allows manual speed selection while it is set to 0. While auto-negotiation is
enabled, DATARATE can be read or written but its value is not required to reflect speed of the link.
1 While auto-negotiation is disabled, selects 100 Mbps operation
0 While auto-negotiation is disabled, selects 10 Mbps operation
12
ANE
Auto-Negotiation Enable bit. This bit determines whether the A/N process is enabled. When
auto-negotiation is disabled, DATARATE and DPLX determine the link configuration. While
auto-negotiation is enabled, bits DATARATE and DPLX do not affect the link.
1 Enables auto-negotiation
0 Disables auto-negotiation
11
PDWN
Power Down bit.
When this bit is set, the port is placed in a low power consumption mode.
1 Port is placed in a low power consumption mode. Normal operation is allowed within 0.5 s after
PDWN and ISOL are changed to 0. During a transition to power-down mode (or if already in power
down mode), the port responds only to management function requests
through the MI interface.
All other port operations are disabled. When power-down mode is exited, all register values are
maintained. The port starts its operation based on the register values.
0 Normal operation
10
ISOL
Isolate bit.
1 Isolates the port’s data path signals from the MII. The port does not respond to changes on
MII_TXDx, MII_TXEN, and MII_TXER inputs, and it presents high impedance on MII_TXCLK,
MII_RXCLK, MII_RXDV, MII_RXER, MII_RXDx, MII_COL, and MII_CRS outputs. The port
responds to management transactions while in isolate mode.
0 Normal operation
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