8101 datasheet(47/172 Pages) LSI

47 / 172 page

8B10B PCS

2-29

2.11.3 Start of Packet

A unique start of packet delimiter (SPD) indicates the start of a packet.

The SPD consists of a single /S/ code inserted at the beginning of the

packet in place of the ﬁrst preamble octet, as deﬁned in the IEEE 802.3z

and shown in Figure 2.3. The /S/ code is deﬁned in Table 2.8.

The transmit 8B10B PCS section inserts an /S/ code at the beginning of

each transmit packet in place of the ﬁrst 10B word of the preamble.

The receive 8B10B PCS section constantly monitors the incoming 10B

bitstream. If an /S/ code is detected, the start of packet indication is given

to the receive MAC, and a preamble octet is substituted in place of the

/S/ code at the beginning of the packet. If the 8B10B PCS receiver

detects the transition from the idle pattern (/I/ code stream) to nonidle

pattern without an intervening /S/ code, the packet is assumed to have

a bad SPD. Packets with a bad SPD are normally discarded as codeword

errors.

Refer to Section 2.13, “Packet Discard” for more information about

discards. Clearing the DIS_CWRD bit in “Register 8–Conﬁguration 2‚"

Section 4.3.9, programs the controller to not discard packets with PCS

codeword errors.

/S/

Start of packet

delimiter (SPD)

/K27.7/

+ or

−

same

/T/

/R/

End of packet

delimiter (EPD)

/K29.7/

/K23.7/

+or

−

+or

−

same

/V/

Error (void)

/K30.7/

+ or

−

same

1. conﬁg_word 1/2 contain the 16-Bit AutoNegotiation data word. See the

AutoNegotiation section for details.

2. RD determined on the /K/ and /D/ characters only, not the conﬁg_word.

Table 2.8

10B Deﬁned Ordered Sets (Cont.)

10B Code

Symbol

Description

10B Codes

Begin

End

8101 Datasheet(PDF) 47 Page - LSI Computer Systems

8101 Datasheet(HTML) 47 Page - LSI Computer Systems

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Datasheet Download

Link URL