LAN83C183 Datasheet, PDF (39/113 Pages) SMSC Corporation – FAST ETHERNET PHYSICAL LAYER DEVICE

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
register to indicate the premature end of packet condition.
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.
SMSC DS – LAN83C183
39
Rev. 12/14/2000