80220/80221
TX_EN = 1
DATA 1
TX_EN = 0
IDLE
TX_EN = 0
IDLE
START
OF
FRAME
DELIM.
PREAMBLE
DATA NIBBLES
DATA 2 DATA N-1 DATA N
PRMBLE
62 BT
SFD
2 BT
= [ 1 0 1 0 ... ] 62 BITS LONG
= [ 1 1 ]
PREAMBLE
SFD
DATAn = [ BETWEEN 64-1518 DATA BYTES ]
IDLE = TX_EN = 0
a.) MII Frame Format
FIRST BIT
MAC’s SERIAL BIT STREAM
LSB
D0
D1
D2
D3
D4
D5
D6
D7
MSB
SECOND
NIBBLE
FIRST
NIBBLE
TXD0 / RXD0
TXD1 / RXD1
TXD2 / RXD2
TXD3 / RXD3
MII
NIBBLE
STREAM
b.) MII Nibble Order
Signals
Bit Value
TXDO
TXD1
TXD2
TXD3
TX_EN
X
X
X
X
0
X
X
X
X
0
11
0
1
0
1
1
0
1
0
1
1
0
1
0
1
1
0
1
0
1
1
0
1
0
1
1
0
1
0
1
1
0
1
0
1
1
0
1
0
1
1
0
1
0
1
1
0
1
0
1
1
0
1
0
1
1
0
1
0
1
1
1
0
1
0
1
12
0
1
0
1
1
0
1
1
1
D03 D44
D1 D5
D2 D6
D3 D7
0
1
0
1
1
1
1. 1st preamble nibble transmitted.
2. 1st sfd nibble transmittted.
3. 1st data nibble transmitted.
4. D0 thru D7 are the first 8 bits of the data field.
c.) Transmit Preamble and SFD bits
Signals Bit Value
RXDO
RXD1
RXD2
RXD3
RX_DV
X
X
X
X
0
11
0
1
0
1
0
1
0
1
1
0
1
0
1
1
0
1
0
1
1
0
1
0
1
1
0
1
0
1
1
0
1
0
1
1
0
1
0
1
1
0
1
0
1
1
0
1
0
1
1
0
1
0
1
1
0
1
0
1
1
0
1
0
1
1
0
1
0
1
1
0
1
0
1
12
0
1
0
1
0
1
1
1
D03 D44
D1 D5
D2 D6
D3 D7
1
1
1
1
1. 1stpreamblenibblereceived. Dependingonmode,devicemayeliminate
either all or some of the preamble nibbles, up to 1st SFD nibble.
2. 1st sfd nibble received.
3. 1st data nibble received.
4. D0 thru D7 are the first 8 bits of the data field.
d.) Receive Preamble and SFD Bits
Figure 3. MII Frame Format
41-111
MD400159/E
LSI [ LSI COMPUTER SYSTEMS ]
