Datasheet

 2017 Microchip Technology Inc. DS00002245B-page 19
KSZ8041NL/RNL
FIGURE 3-1: AUTO-NEGOTIATION FLOW CHART
3.9 MII Management (MIIM) Interface
The KSZ8041NL/RNL supports the IEEE 802.3 MII Management Interface, also known as the Management Data Input
or Output (MDIO) Interface. This interface allows upper-layer devices to monitor and control the state of the
KSZ8041NL/RNL. An external device with MIIM capability is used to read the PHY status or to configure the PHY set-
tings or both. Further details on the MIIM interface can be found in Clause 22.2.4 of the IEEE 802.3 specification.
The MIIM interface consists of the following:
• A physical connection that incorporates the clock line (MDC) and the data line (MDIO).
• A specific protocol that operates across the aforementioned physical connection that allows an external controller
to communicate with one or more PHY devices. Each KSZ8041NL/RNL device is assigned a unique PHY address
between 1 and 7 by its PHYAD[2:0] strapping pins. Additionally, every KSZ8041NL/RNL device supports the
broadcast PHY address 0, as defined per the IEEE 802.3 specification, which can be used to read or write to a
single KSZ8041NL/RNL device, or write to multiple KSZ8041NL/RNL devices simultaneously.
• A set of 16-bit MDIO registers. Registers [0:6] are required, and their functions are defined per the IEEE 802.3
specification. The additional registers are provided for expanded functionality.
Start Auto Ne
g
otiation
Force Link Settin
g
Listen for 10BASE-T
Link Pulses
Listen for 100BASE-TX
Idles
A
ttempt Auto
Ne
g
otiation
Link Mode Set
B
y
pass Auto Ne
g
otiation
and Set Link Mode
Link Mode Set ?
Parallel
Operation
Join
Flow
N
o
Yes
Yes
No