AM79C873KCW datasheet(13/44 Pages) AMD

13 / 44 page

Am79C873

PRELIMINARY

s RX_DV (receive data valid) input from the PHY to in-

dicate the PHY is presenting recovered and de-

coded nibbles to the MAC reconciliation sublayer. To

interpret a receive frame correctly by the reconcilia-

tion sublayer, RX_DV must encompass the frame

starting no later than the Start-of-Frame delimiter

and excluding any End-Stream delimiter.

s RX_ER (receive error) transitions synchronously

with respect to RX_CLK. RX_ER will be asserted

for 1 or more clock per iods to indicate to

the reconciliation sublayer that an error was

detected somewhere in the frame being transmit-

ted from the PHY to the reconciliation sublayer.

s CRS (carrier sense) is asserted by the PHY when

either the transmit or receive medium is non-idle and

deasserted by the PHY when the transmit and receive

medium are idle. Figure 2 depicts the behavior of CRS

during 10BASE-T and 100BASE-TX transmission.

Figure 2.

Carrier Sense during 10BASE-T and 100BASE-TX Transmission

100BASE Operation

The 100BASE transmitter receives 4-bit nibble data

clocked in at 25 MHz at the MII and outputs a scram-

bled 5-bit encoded MLT-3 signal to the media at 100

Mbps. The on-chip clock circuit converts the 25 MHz

clock into a 125 MHz clock for internal use.

The IEEE 802.3u speciﬁcation deﬁnes the Media Inde-

pendent Interface. The interface speciﬁcation deﬁnes a

dedicated receive data bus and a dedicated transmit

data bus.

These two busses include various controls and signal

indications that facilitate data transfers between the

NetPHY-1 device and the Reconciliation layer.

100BASE Transmit

The 100BASE transmitter consists of the functional

blocks shown in Figure 3. The 100BASE transmit sec-

tion converts 4-bit synchronous data provided by the

MII to a scrambled MLT-3 125 million symbols per sec-

ond serial data stream.

TXD

Preamble

SFD

Data

EFD

Preamble

SFD

Data

ESD

T/R

SSD

J/K

10Base-T

100Base-TX

TXD

CRS

IDLE

22164A-4

AM79C873KCW Arkusz danych(PDF) 13 Page - Advanced Micro Devices

AM79C873KCW Arkusz danych(HTML) 13 Page - Advanced Micro Devices

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44

Arkusz danych Pobierz

Link URL