80220 Datasheet, PDF (11/91 Pages) LSI Computer Systems – 100BASE-TX/10BASE-T Ethernet Media Interface Adapter

80220/80221
TX_EN = 0
IDLE
PREAMBLE
PRMBLE
62 BT
START
OF
FRAME
DELIM.
SFD
TX_EN = 1
DATA 1
DATA NIBBLES
DATA 2
DATA N-1
DATA N
2 BT
TX_EN = 0
IDLE
PREAMBLE = [ 1 0 1 0 ... ] 62 BITS LONG
SFD = [ 1 1 ]
DATAn = [ BETWEEN 64-1518 DATA BYTES ]
IDLE = TX_EN = 0
a.) MII Frame Format
MII
NIBBLE
STREAM
FIRST BIT
MAC’s SERIAL BIT STREAM
LSB D0 D1 D2 D3 D4 D5 D6 D7 MSB
FIRST
NIBBLE
SECOND
NIBBLE
TXD0 / RXD0
TXD1 / RXD1
TXD2 / RXD2
TXD3 / RXD3
b.) MII Nibble Order
Signals
TXDO
TXD1
TXD2
TXD3
TX_EN
Bit Value
X X 1¹ 1 1 1 1 1 1 1 1 1 1
XX0 0 0 0 0 0 0 0 0 0 0
XX1 1 1 1 1 1 1 1 1 1 1
XX0 0 0 0 0 0 0 0 0 0 0
0011111111111
11
00
11
00
11
1 1² 1
000
111
001
111
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
D0³ D4⁴
D1 D5
D2 D6
D3 D7
11
Signals Bit Value
RXDO X 1¹ 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1² 1
RXD1 X 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
RXD2 X 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
RXD3 X 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1
RX_DV 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
1. 1st preamble nibble received. Depending on mode, device may eliminate
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
D0³ D4⁴
D1 D5
D2 D6
D3 D7
11
41-111
MD400159/E