80221 datasheet(23/91 Pages) LSI

23 / 91 page

80220/80221

4-23

MD400159/E

The AutoNegotiation algorithm is initiated by any of the

following events: (1) Powerup, (2) device reset, (3) Au-

toNegotiation reset, (4) AutoNegotiation enabled, or (5) a

device enters the Link Fail State. Once a negotiation has

been initiated, the 80220/80221 first determines if the

remote device has AutoNegotiation capability.

If the

remote device is not AutoNegotiation capable and is just

transmitting either a 10Base-T or 100Base-TX signal, the

80220/80221 will sense that and place itself in the correct

mode. If the 80220/80221 detects FLP's from the remote

device, then the remote device is determined to have

AutoNegotiation capability and the device then uses the

contents of the MI serial port AutoNegotiation Advertise-

ment register and FLP's to advertise its capabilities to a

remote device. The remote device does the same, and the

capabilities read back from the remote device are stored in

the MI serial port AutoNegotiation Remote End Capability

The 80220/80221 negotiation algorithm then

matches it's capabilities to the remote device's capabilities

and determines what mode the device should be config-

ured to according to the priority resolution algorithm de-

fined in IEEE 802.3 Clause 28. Once the negotiation

process is completed, the 80220/80221 then configures

itself for either 10 or 100 Mbps mode and either Full or Half

Duplex modes (depending on the outcome of the negotia-

tion process), and it switches to either the 100Base-TX or

10Base-T link integrity algorithms (depending on which

mode was enabled by AutoNegotiation). Refer to IEEE

802.3 Clause 28 for more details.

3.13.5 AutoNegotiation Outcome Indication

The outcome or result of the AutoNegotiation process is

stored in the speed detect and duplex detect bits in the MI

serial port Status Output register.

3.13.6 AutoNegotiation Status

The status of the AutoNegotiation process can be moni-

tored by reading the AutoNegotiation status bits in the MI

serial port Status register.

The MI serial port Status

ment bit which indicates when an AutoNegotiation has

been initiated and successfully completed.

TX_DI

a.) Normal Link Pulse (NLP)

b.) Fast Link Pulse (FLP)

D15

D14

Clock

Data

Figure 8. NLP vs. FLP Link Pulse

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