Kimuro The original MII transfers specificationn data using 4-bit nibbles in each direction 4 transmit data bits, 4 receive data bits. This arrangement allows the MAC to operate without having to be aware of the link speed. Carrier sense is high when transmitting, receiving, or the medium is otherwise sensed as being in use. When no clock can be recovered i. Four things vmii changed compared to the MII standard to achieve this:.
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Kagakus The original MII design has been extended to support reduced signals and increased speeds. The transmit enable signal is held high during frame transmission and low when the transmitter is idle. Being media independent means that different types of PHY devices for connecting to different media i. More recently, raising transmit error outside frame transmission is used to indicate the transmit data lines are gmoi used for special-purpose signalling.
The first 16 addresses have a defined usage,  while the others are device specific. It is not to be confused with RM2. However, at 1 ns edge rates a trace longer than about 2. Data is sampled on the rising edge only i.
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. The standard MII features a specificatiob set of registers: If a collision is detected, COL also goes high while the collision persists.
The specification states that inputs should be 5 V tolerant, however, some popular chips with RMII interfaces are not 5 V tolerant. Media-independent interface — Wikipedia Typically used for on-chip connections; in chip-to-chip usage mostly replaced by XAUI. Views Read Edit View history. Archived from the original on This means a slight modification of the definition of CRS: Retrieved 20 April Four things were changed compared to the Speciifcation 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. 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 tmii that precludes it from being received as valid. Input high threshold is 2. 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.
The receiver clock is much simpler, with only one clock, which is recovered from the specufication data. Drivers should be able to drive 25 pF of capacitance which allows for PCB traces up to 0. The receive clock is recovered from the incoming signal during frame reception. The original MII transfers network data using 4-bit nibbles in each direction 4 transmit data bits, 4 receive data bits. Media-independent interface For receive, two data values are defined: 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. 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. Source-synchronous clocking is used: Reference clock may be an input on both devices from an external clock source, or may be driven from the MAC to the PHY. Ethernet Computer buses Serial buses.
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