RTL8208

2001/01/07

26

Rev.1.923

Receive Path

Receive data and control information are signaled in 10-bit segments. SYNC signal is used to delimit the 10-bit segments. MAC

is responsible to generate these SYNC pulses every ten clocks. For 100Mbps mode, each segment represents a byte of data.

However, for 10Mbps mode, each segment is repeated ten times to represent a byte of data. The receive sequence contains all of

the information defined on the standard MII receive path.

RXD0

RXD1

RXD2

RXD3

RXD4

RXD5

RXD6

RXER from

previous

frame

Speed

0 =10Mbps

1 =100Mbps

Duplex

0 = Half

1 = Full

Link

0 = Down

1 = Up

Jabber

0 = OK

1 = Detected

Upper Nibble

0 = Invalid

1 = Valid

False Carrier

0 = OK

1 = Detected

One Data Byte (Two MII Data Nibbles)

CRS

1

X1

RXD7

RX_DV

X0

SMII Reception Encoding

REFCLK

RXD[0]

SYNC

1

2

3

4

5

6

7

8

9

10

CRS

RXDV

RXD0

RXD7

RXD6

RXD5

RXD4

RXD3

RXD2

RXD1

SMII Reception

Transmit Path

Transmit data and control information are signaled in 10-bit segments. SYNC signal is used to delimit the 10-bit segments. MAC

is responsible to generate these SYNC pulses every ten clocks. For 100Mbps mode, each segment represents a byte of data.

However, for 10Mbps mode, each segment is repeated ten times to represent a byte of data.

XX

X

TXD0

TXD1

TXD2

TXD3

TXD4

TXD5

TXD6

TXD7

TXEN

TXER

One Data Byte (Two MII Data Nibbles)

XXXX

0

X

X

TXD0

TXD1

TXD2

TXD3

TXD4

TXD5

TXD6

TXD7

TXEN

TXER

One Data Byte (Two MII Data Nibbles)

XXXX

0

X

X

TXD0

TXD1

TXD2

TXD3

TXD4

TXD5

TXD6

TXD7

TXEN

TXER

One Data Byte (Two MII Data Nibbles)

X

XXXX

0

X

1

SMII Transmission Encoding

REFCLK

SYNC

TX_ER

TX_EN

TXD0

TXD7

TXD6

TXD5

TXD4

TXD3

TXD2

TXD1

1

2

3

4

5

6

7

8

9

10

REFCLK

SYNC

TX_ER

TX_EN

TXD0

TXD7

TXD6

TXD5

TXD4

TXD3

TXD2

TXD1

1

2

3

4

5

6

7

8

9

10

REFCLK

SYNC

TX_ER

TX_EN

TXD0

TXD7

TXD6

TXD5

TXD4

TXD3

TXD2

TXD1

1

2

3

4

5

6

7

8

9

10

SMII Transmission

Collision Detection

The RTL8208 does not indicate that a collision has occurred. It is left up to the MAC to detect the assertion of both CRS_DV and

TX_EN.