88e3015 Marvell Semiconductor, Inc., 88e3015 Datasheet - Page 27

• Manufacturer Part Number: 88e3015
• Description: Integrated 10/100 Fast Ethernet Transceiver
• Manufacturer: Marvell Semiconductor, Inc.

2.2 Serial Management Interface
The serial management interface provides access to the internal registers via the MDC and MDIO pins and is
compliant to IEEE 802.3u section 22. MDC is the management data clock input and can run from DC to a maxi-
mum rate of 8.33 MHz. MDIO is the management data input/output and is a bi-directional signal that runs synchro-
nously to MDC. The MDIO pin requires a 1.5 kohm pull-up resistor that pulls the MDIO high during idle and
turnaround times.
2.2.1 MDC/MDIO Read and Write Operations
All the relevant serial management registers are implemented as well as several optional registers. A description
of the registers can be found in
Figure 8: Typical MDC/MDIO Read Operation
Figure 9: Typical MDC/MDIO Write Operation
Table 13 is an example of a read operation.
Table 13:
Copyright © 2006 Marvell
October 26, 2006, Advance
32-Bit
Preamble
11111111
example
example
MDC
MDIO
(STA)
MDIO
(PHY)
MDC
MDIO
(STA)
z
z
Idle
Idle
z
z
Serial Management Interface Protocol
0
0
Start
Start
Start of
Frame
01
1
1
Opcode
1
Opcode
(Read)
0
(Write)
0
1
0
Opcode
Read = 10
Write = 01
10
0
1
PHY Address
1
PHY Address
1
Section 3. "Register Description" on page
1
0
0
Document Classification: Proprietary Information
0
0
5-Bit Phy
Device
Address
01100
0
0
Register Address
Register Address
0
0
CONFIDENTIAL
0
0
0
0
5-Bit Phy
Register
Address
00000
0
z
z
0
z
1
TA
TA
0
0
0
0
0
0
2-Bit
Turn-
around
Read = z0
Write = 10
z0
1
0
0
0
0
56.
0
1
0
Register Data
1
16-Bit Data Field
0001001100000000
0
Register Data
0
Serial Management Interface
Doc. No. MV-S103657-00, Rev. C
0
0
0
0
1
0
1
0
0
0
0
0
0
Idle
11111111
0
0
Page 27
0
0
z
z
Idle
Idle
z
z