DM9161C datasheet(21/47 Pages) DAVICOM

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DM9161C

10/100 Mbps Fast Ethernet Physical Layer Single Chip Transceiver

Final

Version: DM9161C-DS-F01

October 26, 2011

Auto-Negotiation

(continued)

Auto-negotiation also provides a parallel detection function for devices that do not support the Auto-negotiation

feature. During Parallel detection there is no exchange of configuration information, instead, the receive signal is

examined. If it is discovered that the signal matches a technology, supported by the receiving device, a

connection will be automatically established using that technology. This allows devices, which do not support

Auto-negotiation but support a common mode of operation, to establish a link.

7.2.7 MII Serial Management

The MII serial management interface consists of a data interface, basic register set, and a serial management

interface to the register set. Through this interface it is possible to control and configure multiple PHY devices,

get status and error information, and determine the type and capabilities of the attached PHY device(s).

The DM9161C management functions correspond to MII specification for IEEE 802.3u-1995 (Clause 22) for

registers 0 through 6 with vendor-specific registers 16, 17, 18, 21, 22, 23 and 24.

In read/write operation, the management data frame is 64-bits long and starts with 32 contiguous logic one bits

(preamble) synchronization clock cycles on MDC. The Start of Frame Delimiter (SFD) is indicated by a <01>

pattern followed by the operation code (OP) :< 10> indicates Read operation and <01> indicates Write operation.

For read operation, a 2-bit turnaround (TA) filing between Register Address field and Data field is provided for

MDIO to avoid contention. Following the turnaround time, 16-bit data is read from or written onto management

registers.

7.2.8 Serial Management Interface

The serial control interface uses a simple two-wired serial interface to obtain and control the status of the

physical layer through the MII interface. The serial control interface consists of MDC (Management Data Clock),

and MDI/O (Management Data Input/Output) signals.

The MDIO pin is bi-directional and may be shared by up to 32 devices.

7.2.9 Management Interface - Read Frame Structure

32 "1"s

Idle Preamble

SFD

Op Code

PHY Address

Turn Around

Data

Idle

Read

Write

MDC

MDIO Read

D15

D14

7.2.10 Management Interface - Write Frame Structure

32 "1"s

D15

D14

Idle Preamble

SFD

Op Code

PHY Address

Turn Around

Data

Idle

Write

MDC

MDIO Write

Figure 7-5

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