The KSZMNX offers the industry-standard GMII/MII Media Independent Interface (GMII) is compliant to the IEEE Specification. Dave Fifield [email protected] GMII Electrical Specification IEEE Interim Meeting, San Diego, January N. Interface) for connection to GMII/MII MACs in Gigabit . Clarified power cycling specification to have all supply voltages to the KSZMNX.

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Media-independent interface – Wikipedia

There is no signal which defines whether the interface is in full or half duplex mode, but both the MAC and the PHY need to agree. The standard MII features a small set of registers: The MAC may omit the signal if it has no use for this functionality, in which case the signal should be tied low for the PHY. Given trends in the semiconductor industry and the fact that both ICs are usually on the same board, lack of 5 V tolerance is probably very common, and chips that actually drive 5 V are probably even rarer.

Reference clock may be an input on both devices from an external clock source, or may be driven from the MAC to the PHY. Input high threshold is 2. On the other hand, newer devices may support 2. This interface requires 9 signals, versus MII’s By using this site, you agree to the Terms of Use and Privacy Policy.

Data is sampled on the rising edge only i. TTL signal levels are used for 5 V or 3. Drivers should be able to drive 25 pF of capacitance which allows for PCB traces up to epecification. It contains a bitmask with the following meaning: The original MII transfers network data using 4-bit nibbles in each direction 4 transmit data bits, 4 receive data specificationn.

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Views Read Edit View history. Typically used for on-chip connections; in chip-to-chip usage mostly replaced by XAUI. This means a slight modification of the definition of CRS: From Wikipedia, the free encyclopedia. For receive, two data values are defined: This page was last edited on 19 Novemberat The specification states that inputs should be 5 V tolerant, however, some popular chips with RMII interfaces are not 5 V tolerant.

Gmi clocking is used: The receive clock is recovered from the incoming signal during frame reception. Archived from the original on Retrieved from ” https: Ethernet Computer buses Serial buses. There are 32 addresses, each containing 16 bits.

Media-independent interface

The transmit enable signal is held high during frame transmission and low when the transmitter is idle. Received clock signal recovered from incoming received data. This arrangement allows the MAC to operate without having to be aware of the link speed. At least the standard says the signals need not be treated as transmission lines. Being media independent means that different types of PHY devices for connecting to different media i.

However, at 1 ns edge rates a trace longer than about 2. For this reason, the reduced media independent interface was developed. The first 16 addresses have a defined usage, [7] while the others are device specific. The RMII signals are treated as lumped signals rather than transmission lines; no termination or controlled impedance is necessary; output drive and thus slew rates need to be as slow as possible rise times from 1—5 ns to permit this.

This may be used to abort a frame when some problem is detected after transmission has already started. Ethernet family of local area network technologies.

This requires the PCB to be designed to add a 1. The receiver clock is much simpler, with only one clock, which is recovered from the incoming data. The management interface controls the behavior of the PHY. These registers can be used to configure the device say “only gigabit, full duplex”, or “only full duplex” or can be used to determine the current operating mode.


Carrier sense is high when transmitting, receiving, or the medium is otherwise sensed as being in use. The media-independent interface MII was originally defined as a standard interface to connect a Fast Ethernet i.

If a collision is detected, COL also goes high while the collision persists. Current revisions of IEEE Four things were changed compared to the MII standard to achieve this:. As such it consists of a preamble, start frame delimiter, Ethernet headers, protocol specific data and a cyclic redundancy check CRC. When no clock can specifivation recovered i.

Some of the preamble nibbles may be lost.

Transmit and receive path each use one differential pair for data and another differential pair for clock. At power up, using autonegotiationthe PHY usually adapts to whatever it is connected to unless settings are altered via the MDIO interface. The original MII design has been extended to support reduced signals and increased speeds.

It is not to be confused with RM2. Transmit error may be raised for one or more clock periods during frame transmission to request the PHY to deliberately corrupt the frame in some visible way that precludes it from being received as valid. More recently, raising transmit error outside frame transmission is used to indicate the transmit data lines are being used for special-purpose signalling.

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