LAN83C183 datasheet(39/113 Pages) SMSC

39 / 113 page

SMSC DS – LAN83C183

Rev. 12/14/2000

1.4 END OF PACKET

This section describes end of packet operation for both the 100 Mbits/s and 10

Mbits/s modes.

1.4.1 100 Mbits/s

The End of Stream Delimiter (ESD) indicates the end of packet for 100 Mbits/s mode.

The ESD pattern consists of two /T/R/ 4B5B symbols inserted after the end of the

packet, as defined in IEEE 802.3 Clause 24 and shown in Table 1.4 and Figure 1.2.

The 4B5B encoder generates the transmit ESD and inserts the /T/R/ symbols after

the end of the transmit data packet, as shown in Figure 1.2.

The 4B5B decoder detects the ESD pattern when there are groups of 10 consecutive

code bits (two 5B words) from the descrambler during valid packet reception.

If the 10 consecutive code bits from the receiver during valid packet reception consist

of the /T/R/ symbols, the end of packet is detected, data reception is terminated, the

CRS and RX_DV pins are asserted, and /I/I/ symbols are substituted in place of the

/T/R/ symbols.

If 10 consecutive code bits from the receiver during valid packet reception do not

consist of /T/R/ symbols, but instead consist of /I/I/ symbols, the packet is considered

to have been terminated prematurely and abnormally, and the end of packet

condition is signalled to the controller interface.

When the premature end of packet condition is detected, the RX_ER signal is

asserted for the nibble associated with the first /I/ symbol detected, then the CRS

and RX_DV pins are deasserted.

The device also sets End of Stream Error bit (ESD) in the MI serial port Status Output

1.4.2 10 Mbits/s

The end of packet for 10 Mbits/s mode is indicated with the SOI (Start of Idle) pulse.

The SOI pulse is a positive double wide pulse containing a Manchester code violation

inserted at the end of every packet.

The TP transmitter generates the transmit SOI pulse and inserts it at the end of the

data packet after TX_EN has been deasserted. The transmit waveshaper shapes the

transmitted SOI output pulse at the TP output to meet the pulse template

requirements specified in IEEE 802.3 Clause 14 and shown in Figure 1.8.

LAN83C183 bảng dữ liệu(PDF) 39 Page - SMSC Corporation