RTL8201BL
management interface follows.
M DC
M DIO
0
1
0
1
A4
A3
A2
A1
A0
R4
R3
R2
R1
R0
1
0
D15 D14 D13 D12 D11 D10 D9
D8
D7
D6
D5
D4
D3
D2
D1
D0
321s
Preamble
ST
OP
PHYAD[4:0]
REGAD[4:0]
TA
DATA
Idle
M DIO issourcedbyM AC.ClockdataintoPHY onrisingedgeofM DC
Write Cycle
M DC
Z
M DIO
0
1
1
0
A4
A3
A2
A1
A0
R4
R3
R2
R1
R0
0
D15 D14 D13 D12 D11 D10 D9
D8
DATA
M DIO issourcedbyPHY.Clockdatafrom PHY onrisingedgeofM DC
D7
D6
D5
D4
D3
D2
D1
D0
321s
Preamble
ST
OP
PHYAD[4:0]
REGAD[4:0]
TA
Idle
M DIO issourcedbyM AC.ClockdataintoPHY onrisingedgeofM DC
Read Cycle
Preamble 32 contiguous logic '1's sent by the MAC on MDIO along with 32 corresponding cycles on MDC. This
provides synchronization for the PHY.
ST
OP
Start of Frame. Indicated by a 01 pattern.
Operation code. Read = 10. Write = 01.
PHYAD PHY Address. Up to 31 PHYs can be connected to one MAC. This 5 bit field selects which PHY the frame is
directed to.
REGAD Register Address. This is a 5 bit field that selects which one of the 32 registers of the PHY this operation refers to.
TA
Turnaround. This is a two bit time spacing between the register address and the data field of a frame to avoid
contention during a read transaction. For a read transaction, both the STA and the PHY shall remain in a
high-impedance state for the first bit time of the turnaround. The PHY shall drive a zero bit during the second
bit time of the turnaround of a read transaction.
DATA
IDLE
Data. These are the 16 bits of Data.
Idle Condition, not actually part of the management frame. This is a high impedance state. Electrically, the
PHY's pull-up resistor will pull the MDIO line to a logic one.
7.2 Auto-negotiation and Parallel Detection
The RTL8201BL supports IEEE 802.3u clause 28 Auto-negotiation operation which can cooperate with other transceivers
supporting auto-negotiation. By this mechanism, the RTL8201BL can auto detect the link partner’s ability and determine the
highest speed/duplex configuration and transmit/receive in this configuration. If the link partner does not support
Auto-negotiation, then the RTL8201BL will enable half duplex mode and enter parallel detection. The RTL8201BL will
default to transmit FLP and wait for the link partner to respond. If the RTL8201BL receives FPL, then the auto-negotiation
process will go on. If it receives NLP, then the RTL8201BL will change to 10Mbps and half duplex mode. If it receives a
100Mbps IDLE pattern, it will change to 100Mbps and half duplex mode.
To enable the auto-negotiation mode operation on the RTL8201BL, just pull the ANE pin high. And the SPEED pin and
DUPLEX pin will set the ability content of auto-negotiation register. The auto-negotiation mode can be externally disabled by
pulling the ANE pin low. In this case, the SPEED pin and DUX pin will change the media configuration of the RTL8201BL.
Below is a list for all configurations of the ANE/SPEED/DUPLEX pins and their operation in Fiber or UTP mode.
Select Medium type and interface mode to MAC
FX
MII/SNIB
Operation mode
(pin 24)
(pin 44)
L
L
H
H
L
UTP mode and MII interface
UTP mode and SNI interface
Fiber mode and MII interface
X
2002-03-29
Rev.1.2
15
ETC [ ETC ]
